Rupert tscheliessnig - Academia.edu (original) (raw)

Papers by Rupert tscheliessnig

Journal of chromatography A/Journal of chromatography, Jun 1, 2024

FEBS Journal, Jun 20, 2023

The interdomain electron transfer (IET) between the catalytic flavodehydrogenase domain and the e... more The interdomain electron transfer (IET) between the catalytic flavodehydrogenase domain and the electron‐transferring cytochrome domain of cellobiose dehydrogenase (CDH) plays an essential role in biocatalysis, biosensors and biofuel cells, as well as in its natural function as an auxiliary enzyme of lytic polysaccharide monooxygenase. We investigated the mobility of the cytochrome and dehydrogenase domains of CDH, which is hypothesised to limit IET in solution by small angle X‐ray scattering (SAXS). CDH from Myriococcum thermophilum (syn. Crassicarpon hotsonii, syn. Thermothelomyces myriococcoides) was probed by SAXS to study the CDH mobility at different pH and in the presence of divalent cations. By comparison of the experimental SAXS data, using pair‐distance distribution functions and Kratky plots, we show an increase in CDH mobility at higher pH, indicating alterations of domain mobility. To further visualise CDH movement in solution, we performed SAXS‐based multistate modelling. Glycan structures present on CDH partially masked the resulting SAXS shapes, we diminished these effects by deglycosylation and studied the effect of glycoforms by modelling. The modelling shows that with increasing pH, the cytochrome domain adopts a more flexible state with significant separation from the dehydrogenase domain. On the contrary, the presence of calcium ions decreases the mobility of the cytochrome domain. Experimental SAXS data, multistate modelling and previously reported kinetic data show how pH and divalent ions impact the closed state necessary for the IET governed by the movement of the CDH cytochrome domain.

Journal of Chemical Physics, Feb 14, 2008

S-layer proteins have a wide range of application potential due to their characteristic features ... more S-layer proteins have a wide range of application potential due to their characteristic features concerning self-assembling, assembling on various surfaces, and forming of isoporous structures with functional groups located on the surface in an identical position and orientation. Although considerable knowledge has been experimentally accumulated on the structure, biochemistry, assemble characteristics, and genetics of S-layer proteins, no structural model at atomic resolution has been available so far. Therefore, neither the overall folding of the S-layer proteins—their tertiary structure—nor the exact amino acid or domain allocations in the lattices are known. In this paper, we describe the tertiary structure prediction for the S-layer protein SbsB from Geobacillus stearothermophilus PV72/p2. This calculation was based on its amino acid sequence using the mean force method (MF method) achieved by performing molecular dynamic simulations. This method includes mainly the thermodynamic aspects of protein folding as well as steric constraints of the amino acids and is therefore independent of experimental structure analysis problems resulting from biochemical properties of the S-layer proteins. Molecular dynamic simulations were performed in vacuum using the simulation software NAMD. The obtained tertiary structure of SbsB was systematically analyzed by using the mean force method, whereas the verification of the structure is based on calculating the global free energy minimum of the whole system. This corresponds to the potential of mean force, which is the thermodynamically most favorable conformation of the protein. Finally, an S-layer lattice was modeled graphically using CINEMA4D and compared with scanning force microscopy data down to a resolution of 1nm. The results show that this approach leads to a thermodynamically favorable atomic model of the tertiary structure of the protein, which could be verified by both the MF Method and the lattice model.

ChemNanoMat, Oct 9, 2018

Hydrothermal synthesis is a widely used technique for the production of TiO2 in various shapes in... more Hydrothermal synthesis is a widely used technique for the production of TiO2 in various shapes in several industries. In the hydrothermal synthesis of TiO2 from a complexed precursor, the processes that occur during the heat-up phase are not fully understood, especially those factors that affect the size and morphology of crystals. Here we report an in situ small angle x-ray scattering analysis to gain insights into the mechanism of early-stage hydrothermal synthesis of TiO2 from a complexed precursor. We observed that the precursor molecules form elongated cuboid-like shapes before they assemble and form the crystal nucleus. One of the edges grows with an exponential behaviour as a function of temperature, while the other two edges remain small. In the following stage, the precursor rods form a characteristic association with a fractal dimension of 2.0 to 2.2. In this stage small particles start to form very slowly within the preformed structures.

Condensed Matter Physics, Feb 1, 2016

The concept of the surface of a protein in solution, as well of the interface between protein and... more The concept of the surface of a protein in solution, as well of the interface between protein and 'bulk solution', is introduced. The experimental technique of small angle X-ray and neutron scattering is introduced and described briefly. Molecular dynamics simulation, as an appropriate computational tool for studying the hydration shell of proteins, is also discussed. The concept of protein surfaces with fractal dimensions is elaborated. We finish by exposing an experimental (using small angle X-ray scattering) and a computer simulation case study, which are meant as demonstrations of the possibilities we have at hand for investigating the delicate interfaces that connect (and divide) protein molecules and the neighboring electrolyte solution.

Journal of Separation Science, Oct 1, 2010

The adsorption of plasmid DNA onto two different types of ceramic hydroxyapatite beads with a par... more The adsorption of plasmid DNA onto two different types of ceramic hydroxyapatite beads with a particle diameter of 20 mm, namely Ceramic Hydroxyapatite Type II and the Type III, which is not commercially available, were investigated. Type II and the Type III have a pore diameter of 80 and 240 nm, respectively. Equilibrium and dynamic binding capacity for a 4.9 kbp model plasmid on Ceramic Hydroxyapatite Type II and Type III were enhanced by addition of NaCl to the adsorption buffer. This result indicates that the adsorption mechanism cannot be solely explained by electrostatic interaction. The affinities of plasmid DNA for Ceramic Hydroxyapatite Type II (with a K D of E0.005 mg/mL) and to Hydroxyapatite Type III (with a K D of E0.045 mg/mL) were not affected by NaCl, whereas the binding capacity was. This observation corroborates the assumption that a change of the shape of the plasmid molecule is affected and could be the reason for increased binding capacity with salt. The maximal binding capacity shows that at least a part of the CHT II bead must be accessible for the plasmid, whereas CHT III can be saturated with the plasmid. In both cases, an extremely hindered transport takes place.

Biotechnology and Bioengineering, Aug 15, 2017

This article has been accepted for publication and undergone full peer review but has not been th... more This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as

Surface Science, May 1, 2001

Adsorption of oxygen on Al(111) is studied by scanning tunneling microscopy at 80 and 300 K. Afte... more Adsorption of oxygen on Al(111) is studied by scanning tunneling microscopy at 80 and 300 K. After adsorption at 130±195 K, STM images taken at 80 K show pairs of oxygen adatoms with interatomic distances mainly between one and three Al interatomic spacings. This clearly shows that dissociation of the oxygen molecules results in a rather low transient mobility of the two oxygen atoms, a fact which is in contrast to previous work [Phys. Rev. Lett. 68 (1992) 624]. We also ®nd evidence for oxygen atoms in a second metastable adsorption site at these temperatures. At room temperature, we ®nd groups of two or more oxygen atoms in adjacent fcc hollow sites, but no single oxygen atoms. We therefore explain the room-temperature results by part of the oxygen pairs remaining or becoming nearest neighbors, whereas others separate by diusion and their oxygen atoms attach to other pairs or groups, forming the larger groups found. The pairs and larger groups are stable due to an attractive interaction of oxygen atoms in adjacent fcc hollow sites.

New Biotechnology, 2016

In spite of the importance of Chinese Hamster Ovary (CHO) cells for recombinant protein productio... more In spite of the importance of Chinese Hamster Ovary (CHO) cells for recombinant protein production, very little data is available

Biotechnology Journal, 2019

Protein A affinity chromatography is a core unit operation in antibody manufacturing. Nevertheles... more Protein A affinity chromatography is a core unit operation in antibody manufacturing. Nevertheless, there is not enough understanding of in‐column antibody adsorption in the Protein A capture step. This work aims to investigate in situ the establishment of an antibody (trastuzumab) layer during Protein A chromatography both in terms of energetic contributions and uptake kinetics. Flow microcalorimetry is employed as a technique with an in situ operating detector, which provides an understanding of the thermodynamics of the adsorption process. In addition, the antibody uptake rate is also investigated in order to establish a correlation between its diffusion on the stationary phase and the associated thermodynamics. Two resins with different particle size, intraparticle porosity, and a Protein A ligand structure are studied: the synthetically engineered B‐domain tetrameric MabSelect SuRe and the synthetically engineered C‐domain hexameric TOYOPEARL AF‐rProtein A HC. The uptake rate f...

ChemNanoMat, 2018

Hydrothermal synthesis is a widely used technique for the production of TiO2 in various shapes in... more Hydrothermal synthesis is a widely used technique for the production of TiO2 in various shapes in several industries. In the hydrothermal synthesis of TiO2 from a complexed precursor, the processes that occur during the heat‐up phase are not fully understood, especially those factors that affect the size and morphology of crystals. Here we report an in situ small angle x‐ray scattering analysis to gain insights into the mechanism of early‐stage hydrothermal synthesis of TiO2 from a complexed precursor. We observed that the precursor molecules form elongated cuboid‐like shapes before they assemble and form the crystal nucleus. One of the edges grows with an exponential behaviour as a function of temperature, while the other two edges remain small. In the following stage, the precursor rods form a characteristic association with a fractal dimension of 2.0 to 2.2. In this stage small particles start to form very slowly within the preformed structures.

Biotechnology and Bioengineering, 2017

ABSTRACTWe have investigated the structures of two native cutinases from Thermobifida cellulosily... more ABSTRACTWe have investigated the structures of two native cutinases from Thermobifida cellulosilytica, namely Thc_Cut1 and Thc_Cut2 as well as of two variants, Thc_Cut2_DM (Thc_Cut2_ Arg29Asn_Ala30Val) and Thc_Cut2_TM (Thc_Cut2_Arg19Ser_Arg29Asn_Ala30Val). The four enzymes showed different activities towards the aliphatic polyester poly(lactic acid) (PLLA). The crystal structures of the four enzymes were successfully solved and in combination with Small Angle X‐Ray Scattering (SAXS) the structural features responsible for the selectivity difference were elucidated. Analysis of the crystal structures did not indicate significant conformational differences among the different cutinases. However, the distinctive SAXS scattering data collected from the enzymes in solution indicated a remarkable surface charge difference. The difference in the electrostatic and hydrophobic surface properties could explain potential alternative binding modes of the four cutinases on PLLA explaining their ...

Condensed Matter Physics, 2016

The concept of the surface of a protein in solution, as well of the interface between protein and... more The concept of the surface of a protein in solution, as well of the interface between protein and 'bulk solution', is introduced. The experimental technique of small angle X-ray and neutron scattering is introduced and described briefly. Molecular dynamics simulation, as an appropriate computational tool for studying the hydration shell of proteins, is also discussed. The concept of protein surfaces with fractal dimensions is elaborated. We finish by exposing an experimental (using small angle X-ray scattering) and a computer simulation case study, which are meant as demonstrations of the possibilities we have at hand for investigating the delicate interfaces that connect (and divide) protein molecules and the neighboring electrolyte solution.

Surface Science, 2001

Adsorption of oxygen on Al(111) is studied by scanning tunneling microscopy at 80 and 300 K. Afte... more Adsorption of oxygen on Al(111) is studied by scanning tunneling microscopy at 80 and 300 K. After adsorption at 130±195 K, STM images taken at 80 K show pairs of oxygen adatoms with interatomic distances mainly between one and three Al interatomic spacings. This clearly shows that dissociation of the oxygen molecules results in a rather low transient mobility of the two oxygen atoms, a fact which is in contrast to previous work [Phys. Rev. Lett. 68 (1992) 624]. We also ®nd evidence for oxygen atoms in a second metastable adsorption site at these temperatures. At room temperature, we ®nd groups of two or more oxygen atoms in adjacent fcc hollow sites, but no single oxygen atoms. We therefore explain the room-temperature results by part of the oxygen pairs remaining or becoming nearest neighbors, whereas others separate by diusion and their oxygen atoms attach to other pairs or groups, forming the larger groups found. The pairs and larger groups are stable due to an attractive interaction of oxygen atoms in adjacent fcc hollow sites.

Journal of Separation Science, 2010

The adsorption of plasmid DNA onto two different types of ceramic hydroxyapatite beads with a par... more The adsorption of plasmid DNA onto two different types of ceramic hydroxyapatite beads with a particle diameter of 20 mm, namely Ceramic Hydroxyapatite Type II and the Type III, which is not commercially available, were investigated. Type II and the Type III have a pore diameter of 80 and 240 nm, respectively. Equilibrium and dynamic binding capacity for a 4.9 kbp model plasmid on Ceramic Hydroxyapatite Type II and Type III were enhanced by addition of NaCl to the adsorption buffer. This result indicates that the adsorption mechanism cannot be solely explained by electrostatic interaction. The affinities of plasmid DNA for Ceramic Hydroxyapatite Type II (with a K D of E0.005 mg/mL) and to Hydroxyapatite Type III (with a K D of E0.045 mg/mL) were not affected by NaCl, whereas the binding capacity was. This observation corroborates the assumption that a change of the shape of the plasmid molecule is affected and could be the reason for increased binding capacity with salt. The maximal binding capacity shows that at least a part of the CHT II bead must be accessible for the plasmid, whereas CHT III can be saturated with the plasmid. In both cases, an extremely hindered transport takes place.

The Journal of Chemical Physics, 2007

A density functional and Monte Carlo simulation study of end-grafted polymers immersed by simple ... more A density functional and Monte Carlo simulation study of end-grafted polymers immersed by simple fluids is presented. The polymer molecules are modeled as freely jointed tangent hard spheres with the end segments linked to the surface. The authors analyze an influence of the chain length, the grafting density, and a nature of solvent on the brush structure. Adsorption of hard-sphere mixtures on the modified surface is also discussed. The theory precisely approximates simulation data.

The Journal of Chemical Physics, 2007

A simple density functional approach for modeling the adsorption of biomolecules is considered. T... more A simple density functional approach for modeling the adsorption of biomolecules is considered. The model comprises a three-component mixture consisting of spherical and differently charged ions and chain molecules. Spherical ions can form associative bonds with selected segments of a chain. To enable the formation of bonds between chain segments and spherical ions, the statistical associating fluid theory is applied. The present theory is used to study the structure of adsorbed layers, the excess adsorption isotherms, and the capacitance of the double layer.

The Journal of Chemical Physics, 2008

S-layer proteins have a wide range of application potential due to their characteristic features ... more S-layer proteins have a wide range of application potential due to their characteristic features concerning self-assembling, assembling on various surfaces, and forming of isoporous structures with functional groups located on the surface in an identical position and orientation. Although considerable knowledge has been experimentally accumulated on the structure, biochemistry, assemble characteristics, and genetics of S-layer proteins, no structural model at atomic resolution has been available so far. Therefore, neither the overall folding of the S-layer proteins—their tertiary structure—nor the exact amino acid or domain allocations in the lattices are known. In this paper, we describe the tertiary structure prediction for the S-layer protein SbsB from Geobacillus stearothermophilus PV72/p2. This calculation was based on its amino acid sequence using the mean force method (MF method) achieved by performing molecular dynamic simulations. This method includes mainly the thermodynam...

Journal of chromatography A/Journal of chromatography, Jun 1, 2024

FEBS Journal, Jun 20, 2023

The interdomain electron transfer (IET) between the catalytic flavodehydrogenase domain and the e... more The interdomain electron transfer (IET) between the catalytic flavodehydrogenase domain and the electron‐transferring cytochrome domain of cellobiose dehydrogenase (CDH) plays an essential role in biocatalysis, biosensors and biofuel cells, as well as in its natural function as an auxiliary enzyme of lytic polysaccharide monooxygenase. We investigated the mobility of the cytochrome and dehydrogenase domains of CDH, which is hypothesised to limit IET in solution by small angle X‐ray scattering (SAXS). CDH from Myriococcum thermophilum (syn. Crassicarpon hotsonii, syn. Thermothelomyces myriococcoides) was probed by SAXS to study the CDH mobility at different pH and in the presence of divalent cations. By comparison of the experimental SAXS data, using pair‐distance distribution functions and Kratky plots, we show an increase in CDH mobility at higher pH, indicating alterations of domain mobility. To further visualise CDH movement in solution, we performed SAXS‐based multistate modelling. Glycan structures present on CDH partially masked the resulting SAXS shapes, we diminished these effects by deglycosylation and studied the effect of glycoforms by modelling. The modelling shows that with increasing pH, the cytochrome domain adopts a more flexible state with significant separation from the dehydrogenase domain. On the contrary, the presence of calcium ions decreases the mobility of the cytochrome domain. Experimental SAXS data, multistate modelling and previously reported kinetic data show how pH and divalent ions impact the closed state necessary for the IET governed by the movement of the CDH cytochrome domain.

Journal of Chemical Physics, Feb 14, 2008

S-layer proteins have a wide range of application potential due to their characteristic features ... more S-layer proteins have a wide range of application potential due to their characteristic features concerning self-assembling, assembling on various surfaces, and forming of isoporous structures with functional groups located on the surface in an identical position and orientation. Although considerable knowledge has been experimentally accumulated on the structure, biochemistry, assemble characteristics, and genetics of S-layer proteins, no structural model at atomic resolution has been available so far. Therefore, neither the overall folding of the S-layer proteins—their tertiary structure—nor the exact amino acid or domain allocations in the lattices are known. In this paper, we describe the tertiary structure prediction for the S-layer protein SbsB from Geobacillus stearothermophilus PV72/p2. This calculation was based on its amino acid sequence using the mean force method (MF method) achieved by performing molecular dynamic simulations. This method includes mainly the thermodynamic aspects of protein folding as well as steric constraints of the amino acids and is therefore independent of experimental structure analysis problems resulting from biochemical properties of the S-layer proteins. Molecular dynamic simulations were performed in vacuum using the simulation software NAMD. The obtained tertiary structure of SbsB was systematically analyzed by using the mean force method, whereas the verification of the structure is based on calculating the global free energy minimum of the whole system. This corresponds to the potential of mean force, which is the thermodynamically most favorable conformation of the protein. Finally, an S-layer lattice was modeled graphically using CINEMA4D and compared with scanning force microscopy data down to a resolution of 1nm. The results show that this approach leads to a thermodynamically favorable atomic model of the tertiary structure of the protein, which could be verified by both the MF Method and the lattice model.

ChemNanoMat, Oct 9, 2018

Hydrothermal synthesis is a widely used technique for the production of TiO2 in various shapes in... more Hydrothermal synthesis is a widely used technique for the production of TiO2 in various shapes in several industries. In the hydrothermal synthesis of TiO2 from a complexed precursor, the processes that occur during the heat-up phase are not fully understood, especially those factors that affect the size and morphology of crystals. Here we report an in situ small angle x-ray scattering analysis to gain insights into the mechanism of early-stage hydrothermal synthesis of TiO2 from a complexed precursor. We observed that the precursor molecules form elongated cuboid-like shapes before they assemble and form the crystal nucleus. One of the edges grows with an exponential behaviour as a function of temperature, while the other two edges remain small. In the following stage, the precursor rods form a characteristic association with a fractal dimension of 2.0 to 2.2. In this stage small particles start to form very slowly within the preformed structures.

Condensed Matter Physics, Feb 1, 2016

The concept of the surface of a protein in solution, as well of the interface between protein and... more The concept of the surface of a protein in solution, as well of the interface between protein and 'bulk solution', is introduced. The experimental technique of small angle X-ray and neutron scattering is introduced and described briefly. Molecular dynamics simulation, as an appropriate computational tool for studying the hydration shell of proteins, is also discussed. The concept of protein surfaces with fractal dimensions is elaborated. We finish by exposing an experimental (using small angle X-ray scattering) and a computer simulation case study, which are meant as demonstrations of the possibilities we have at hand for investigating the delicate interfaces that connect (and divide) protein molecules and the neighboring electrolyte solution.

Journal of Separation Science, Oct 1, 2010

The adsorption of plasmid DNA onto two different types of ceramic hydroxyapatite beads with a par... more The adsorption of plasmid DNA onto two different types of ceramic hydroxyapatite beads with a particle diameter of 20 mm, namely Ceramic Hydroxyapatite Type II and the Type III, which is not commercially available, were investigated. Type II and the Type III have a pore diameter of 80 and 240 nm, respectively. Equilibrium and dynamic binding capacity for a 4.9 kbp model plasmid on Ceramic Hydroxyapatite Type II and Type III were enhanced by addition of NaCl to the adsorption buffer. This result indicates that the adsorption mechanism cannot be solely explained by electrostatic interaction. The affinities of plasmid DNA for Ceramic Hydroxyapatite Type II (with a K D of E0.005 mg/mL) and to Hydroxyapatite Type III (with a K D of E0.045 mg/mL) were not affected by NaCl, whereas the binding capacity was. This observation corroborates the assumption that a change of the shape of the plasmid molecule is affected and could be the reason for increased binding capacity with salt. The maximal binding capacity shows that at least a part of the CHT II bead must be accessible for the plasmid, whereas CHT III can be saturated with the plasmid. In both cases, an extremely hindered transport takes place.

Biotechnology and Bioengineering, Aug 15, 2017

This article has been accepted for publication and undergone full peer review but has not been th... more This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as

Surface Science, May 1, 2001

Adsorption of oxygen on Al(111) is studied by scanning tunneling microscopy at 80 and 300 K. Afte... more Adsorption of oxygen on Al(111) is studied by scanning tunneling microscopy at 80 and 300 K. After adsorption at 130±195 K, STM images taken at 80 K show pairs of oxygen adatoms with interatomic distances mainly between one and three Al interatomic spacings. This clearly shows that dissociation of the oxygen molecules results in a rather low transient mobility of the two oxygen atoms, a fact which is in contrast to previous work [Phys. Rev. Lett. 68 (1992) 624]. We also ®nd evidence for oxygen atoms in a second metastable adsorption site at these temperatures. At room temperature, we ®nd groups of two or more oxygen atoms in adjacent fcc hollow sites, but no single oxygen atoms. We therefore explain the room-temperature results by part of the oxygen pairs remaining or becoming nearest neighbors, whereas others separate by diusion and their oxygen atoms attach to other pairs or groups, forming the larger groups found. The pairs and larger groups are stable due to an attractive interaction of oxygen atoms in adjacent fcc hollow sites.

New Biotechnology, 2016

In spite of the importance of Chinese Hamster Ovary (CHO) cells for recombinant protein productio... more In spite of the importance of Chinese Hamster Ovary (CHO) cells for recombinant protein production, very little data is available

Biotechnology Journal, 2019

Protein A affinity chromatography is a core unit operation in antibody manufacturing. Nevertheles... more Protein A affinity chromatography is a core unit operation in antibody manufacturing. Nevertheless, there is not enough understanding of in‐column antibody adsorption in the Protein A capture step. This work aims to investigate in situ the establishment of an antibody (trastuzumab) layer during Protein A chromatography both in terms of energetic contributions and uptake kinetics. Flow microcalorimetry is employed as a technique with an in situ operating detector, which provides an understanding of the thermodynamics of the adsorption process. In addition, the antibody uptake rate is also investigated in order to establish a correlation between its diffusion on the stationary phase and the associated thermodynamics. Two resins with different particle size, intraparticle porosity, and a Protein A ligand structure are studied: the synthetically engineered B‐domain tetrameric MabSelect SuRe and the synthetically engineered C‐domain hexameric TOYOPEARL AF‐rProtein A HC. The uptake rate f...

ChemNanoMat, 2018

Hydrothermal synthesis is a widely used technique for the production of TiO2 in various shapes in... more Hydrothermal synthesis is a widely used technique for the production of TiO2 in various shapes in several industries. In the hydrothermal synthesis of TiO2 from a complexed precursor, the processes that occur during the heat‐up phase are not fully understood, especially those factors that affect the size and morphology of crystals. Here we report an in situ small angle x‐ray scattering analysis to gain insights into the mechanism of early‐stage hydrothermal synthesis of TiO2 from a complexed precursor. We observed that the precursor molecules form elongated cuboid‐like shapes before they assemble and form the crystal nucleus. One of the edges grows with an exponential behaviour as a function of temperature, while the other two edges remain small. In the following stage, the precursor rods form a characteristic association with a fractal dimension of 2.0 to 2.2. In this stage small particles start to form very slowly within the preformed structures.

Biotechnology and Bioengineering, 2017

ABSTRACTWe have investigated the structures of two native cutinases from Thermobifida cellulosily... more ABSTRACTWe have investigated the structures of two native cutinases from Thermobifida cellulosilytica, namely Thc_Cut1 and Thc_Cut2 as well as of two variants, Thc_Cut2_DM (Thc_Cut2_ Arg29Asn_Ala30Val) and Thc_Cut2_TM (Thc_Cut2_Arg19Ser_Arg29Asn_Ala30Val). The four enzymes showed different activities towards the aliphatic polyester poly(lactic acid) (PLLA). The crystal structures of the four enzymes were successfully solved and in combination with Small Angle X‐Ray Scattering (SAXS) the structural features responsible for the selectivity difference were elucidated. Analysis of the crystal structures did not indicate significant conformational differences among the different cutinases. However, the distinctive SAXS scattering data collected from the enzymes in solution indicated a remarkable surface charge difference. The difference in the electrostatic and hydrophobic surface properties could explain potential alternative binding modes of the four cutinases on PLLA explaining their ...

Condensed Matter Physics, 2016

The concept of the surface of a protein in solution, as well of the interface between protein and... more The concept of the surface of a protein in solution, as well of the interface between protein and 'bulk solution', is introduced. The experimental technique of small angle X-ray and neutron scattering is introduced and described briefly. Molecular dynamics simulation, as an appropriate computational tool for studying the hydration shell of proteins, is also discussed. The concept of protein surfaces with fractal dimensions is elaborated. We finish by exposing an experimental (using small angle X-ray scattering) and a computer simulation case study, which are meant as demonstrations of the possibilities we have at hand for investigating the delicate interfaces that connect (and divide) protein molecules and the neighboring electrolyte solution.

Surface Science, 2001

Adsorption of oxygen on Al(111) is studied by scanning tunneling microscopy at 80 and 300 K. Afte... more Adsorption of oxygen on Al(111) is studied by scanning tunneling microscopy at 80 and 300 K. After adsorption at 130±195 K, STM images taken at 80 K show pairs of oxygen adatoms with interatomic distances mainly between one and three Al interatomic spacings. This clearly shows that dissociation of the oxygen molecules results in a rather low transient mobility of the two oxygen atoms, a fact which is in contrast to previous work [Phys. Rev. Lett. 68 (1992) 624]. We also ®nd evidence for oxygen atoms in a second metastable adsorption site at these temperatures. At room temperature, we ®nd groups of two or more oxygen atoms in adjacent fcc hollow sites, but no single oxygen atoms. We therefore explain the room-temperature results by part of the oxygen pairs remaining or becoming nearest neighbors, whereas others separate by diusion and their oxygen atoms attach to other pairs or groups, forming the larger groups found. The pairs and larger groups are stable due to an attractive interaction of oxygen atoms in adjacent fcc hollow sites.

Journal of Separation Science, 2010

The adsorption of plasmid DNA onto two different types of ceramic hydroxyapatite beads with a par... more The adsorption of plasmid DNA onto two different types of ceramic hydroxyapatite beads with a particle diameter of 20 mm, namely Ceramic Hydroxyapatite Type II and the Type III, which is not commercially available, were investigated. Type II and the Type III have a pore diameter of 80 and 240 nm, respectively. Equilibrium and dynamic binding capacity for a 4.9 kbp model plasmid on Ceramic Hydroxyapatite Type II and Type III were enhanced by addition of NaCl to the adsorption buffer. This result indicates that the adsorption mechanism cannot be solely explained by electrostatic interaction. The affinities of plasmid DNA for Ceramic Hydroxyapatite Type II (with a K D of E0.005 mg/mL) and to Hydroxyapatite Type III (with a K D of E0.045 mg/mL) were not affected by NaCl, whereas the binding capacity was. This observation corroborates the assumption that a change of the shape of the plasmid molecule is affected and could be the reason for increased binding capacity with salt. The maximal binding capacity shows that at least a part of the CHT II bead must be accessible for the plasmid, whereas CHT III can be saturated with the plasmid. In both cases, an extremely hindered transport takes place.

The Journal of Chemical Physics, 2007

A density functional and Monte Carlo simulation study of end-grafted polymers immersed by simple ... more A density functional and Monte Carlo simulation study of end-grafted polymers immersed by simple fluids is presented. The polymer molecules are modeled as freely jointed tangent hard spheres with the end segments linked to the surface. The authors analyze an influence of the chain length, the grafting density, and a nature of solvent on the brush structure. Adsorption of hard-sphere mixtures on the modified surface is also discussed. The theory precisely approximates simulation data.

The Journal of Chemical Physics, 2007

A simple density functional approach for modeling the adsorption of biomolecules is considered. T... more A simple density functional approach for modeling the adsorption of biomolecules is considered. The model comprises a three-component mixture consisting of spherical and differently charged ions and chain molecules. Spherical ions can form associative bonds with selected segments of a chain. To enable the formation of bonds between chain segments and spherical ions, the statistical associating fluid theory is applied. The present theory is used to study the structure of adsorbed layers, the excess adsorption isotherms, and the capacitance of the double layer.

The Journal of Chemical Physics, 2008

S-layer proteins have a wide range of application potential due to their characteristic features ... more S-layer proteins have a wide range of application potential due to their characteristic features concerning self-assembling, assembling on various surfaces, and forming of isoporous structures with functional groups located on the surface in an identical position and orientation. Although considerable knowledge has been experimentally accumulated on the structure, biochemistry, assemble characteristics, and genetics of S-layer proteins, no structural model at atomic resolution has been available so far. Therefore, neither the overall folding of the S-layer proteins—their tertiary structure—nor the exact amino acid or domain allocations in the lattices are known. In this paper, we describe the tertiary structure prediction for the S-layer protein SbsB from Geobacillus stearothermophilus PV72/p2. This calculation was based on its amino acid sequence using the mean force method (MF method) achieved by performing molecular dynamic simulations. This method includes mainly the thermodynam...