John Schloss - Academia.edu (original) (raw)
Papers by John Schloss
The Changhua Journal of Medicine, Jul 1, 2001
Primary cultured neurons are significantly damaged by brief exposure to 0.25mM glutamate (Glu). T... more Primary cultured neurons are significantly damaged by brief exposure to 0.25mM glutamate (Glu). The neuronal damage, as indicated by cell lysis, was not distinguishable until at least 6 to 8 hour after Glu exposure. Inclusion of taurine at 25mM in the extracellular medium reduced Glu-induced neuronal injury. The neuroprotective effect of taurine was not affected by the presence of taurine transport inhibitors, e.g. guanidinoethyl sulfonate (GES) and β-alanine, indicating that intracellular uptake of taurine is not necessary for the neuroprotection by taurine. The presence of 25mM taurine in the medium did not cause a significant change of total intracellular taurine level during Glutreatment. It also had little effect on Glu-induced cell swelling as indicated by [(superscript 3)H]taurine efflux. However, taurine exhibited a remarkable effect on Glu-induced elevation of intracellular calcium level [Ca(surperscript 2+)](subscript i). Therefore, we conclude that the neuroprotection of taurine against Glu-induced neurotoxicity observed in cultured neurons is primarily a result of reducing the level of [Ca(superscript 2+)](subscript i), rather than serving as an osmoregulator.
Kluwer Academic Publishers eBooks, 1990
Bioorganic Chemistry, Jun 1, 1980
ABSTRACT
Biochemical and Biophysical Research Communications, Jul 1, 1977
amino-acid oxidase with propargylglycine, in which both irreversible (Marcotte and Walsh, 1978a) ... more amino-acid oxidase with propargylglycine, in which both irreversible (Marcotte and Walsh, 1978a) and reversible (Marcotte and Walsh, 1978b) interactions are observed. This work has demonstrated that, when reaction between an enzyme and a substrate analogue results in release of a highly reactive product, it is necessary to characterize the pathway following the enzymatic step to determine if any species formed subsequently interacts with that enzyme or other enzymes in vivo.
Biomedicines, Jul 3, 2023
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
![Research paper thumbnail of Isolation, characterization, and crystallization of ribulosebisphosphate carboxylase from autotrophically grown Rhodospirillum rubrum. [/sup 14/C tracer technique]](https://attachments.academia-assets.com/109964439/thumbnails/1.jpg)
](An iron containing superoxide dismutase from the cytosol of the thermoacidophilic crenarchaeon Su... more An iron containing superoxide dismutase from the cytosol of the thermoacidophilic crenarchaeon Sulfolobus acidocaldarius (DSM 639) has been purified to electrophoretic homogeneity. It comprises at least 11% of the cytosolic protein. The isolated protein consists of two identical subunits with an apparent molecular mass of 22.4 kDa. It contains one iron atom per dimer. The protein shows the typical EPR spectrum of a S = 3/2, rhombic high-spin iron center. It is extremely resistant against thermal and chemical denaturation. Simultaneous treatment with heat and detergent resulted in the conversion into a more active tetrameric form. Similar enzymes appear to be present in the cytosol of other members of the Sulfolobaceue. The dimeric form of the protein from S. acidoculdurius has been crystallized.
![Research paper thumbnail of Inactivation of ribulosebisphosphate carboxylase by modification of arginyl residues with phenylglyoxal. [Spinach, Rhodospirillum rubrum]](https://attachments.academia-assets.com/109743816/thumbnails/1.jpg)
](Biochemistry, Dec 26, 1978
amino-acid oxidase with propargylglycine, in which both irreversible (Marcotte and Walsh, 1978a) ... more amino-acid oxidase with propargylglycine, in which both irreversible (Marcotte and Walsh, 1978a) and reversible (Marcotte and Walsh, 1978b) interactions are observed. This work has demonstrated that, when reaction between an enzyme and a substrate analogue results in release of a highly reactive product, it is necessary to characterize the pathway following the enzymatic step to determine if any species formed subsequently interacts with that enzyme or other enzymes in vivo.
Journal of Bacteriology, 1979
An iron containing superoxide dismutase from the cytosol of the thermoacidophilic crenarchaeon Su... more An iron containing superoxide dismutase from the cytosol of the thermoacidophilic crenarchaeon Sulfolobus acidocaldarius (DSM 639) has been purified to electrophoretic homogeneity. It comprises at least 11% of the cytosolic protein. The isolated protein consists of two identical subunits with an apparent molecular mass of 22.4 kDa. It contains one iron atom per dimer. The protein shows the typical EPR spectrum of a S = 3/2, rhombic high-spin iron center. It is extremely resistant against thermal and chemical denaturation. Simultaneous treatment with heat and detergent resulted in the conversion into a more active tetrameric form. Similar enzymes appear to be present in the cytosol of other members of the Sulfolobaceue. The dimeric form of the protein from S. acidoculdurius has been crystallized.
Advances in Space Research, 1992
Springer eBooks, 1990
Enzy~at1c and model carboxylation and reduction reactions for carbon d10x1de ut1l1zat10n ! edited... more Enzy~at1c and model carboxylation and reduction reactions for carbon d10x1de ut1l1zat10n ! edited by M. Aresta and J.V. Schloss. p. cm.-(NATO ASI series. Series C. Mathemat1cal and physical sciences; vol. 314) papers from a NATO Advanced Study Institute summer school held June 17-28. 1989 1n Ginosa • Italy. flncludes bib I iographical references and 1noex.
Inflammopharmacology
Multiple nutritional deficiencies (MND) confound studies designed to assess the role of a single ... more Multiple nutritional deficiencies (MND) confound studies designed to assess the role of a single nutrient in contributing to the initiation and progression of disease states. Despite the perception of many healthcare practitioners, up to 25% of Americans are deficient in five-or-more essential nutrients. Stress associated with the COVID-19 pandemic further increases the prevalence of deficiency states. Viral infections compete for crucial nutrients with immune cells. Viral replication and proliferation of immunocompetent cells critical to the host response require these essential nutrients, including zinc. Clinical studies have linked levels of more than 22 different dietary components to the likelihood of COVID-19 infection and the severity of the disease. People at higher risk of infection due to MND are also more likely to have long-term sequelae, known as Long COVID. Keywords Multiple nutritional deficiencies • Lymphocyte proliferation assay • Myeloperoxidase • Glutathione peroxidase isozyme 4 • NADPH oxidase 2 Abbreviations MND Multiple nutritional deficiencies LPA Lymphocyte proliferation assay MPO Myeloperoxidase GPX4 Glutathione peroxidase isozyme 4 NOX2 NADPH oxidase 2
IDrugs : the investigational drugs journal, 1998
This symposium was organized by Dan Flynn (Monsanto Life Sciences, USA) and Timothy M Willson (Gl... more This symposium was organized by Dan Flynn (Monsanto Life Sciences, USA) and Timothy M Willson (Glaxo Wellcome, USA). PPARs (peroxisome proliferator-activated receptors), are nuclear hormone receptors that govern glucose and lipid homeostasis. There are several subtypes of receptors that share activation by unsaturated fatty acids and work in combination with retinoic acid receptors (RXR), which were a topic covered in an earlier symposium. Two classes of chemistry were discussed at the symposium: (i) thiazolidinediones, that interact directly with PPARs and alter lipid metabolism; and, (ii) benzothiepines or benzothiazepines, that inhibit the ileal bile acid transporter (IBAT) and reduce cholesterol levels by increasing bile acid excretion.
Advances in Enzymology - and Related Areas of Molecular Biology, 2011
I. Overview Enzymes that generate carbanionic intermediates often catalyze paracatalytic reaction... more I. Overview Enzymes that generate carbanionic intermediates often catalyze paracatalytic reactions with O 2 and other electrophiles not considered "normal" reactants. For example, pyridoxal 5′phosphate (PLP)-containing pig kidney dopa decarboxylase oxidizes dopamine with molecular O 2 to 3,4-dihydroxyphenylacetaldehyde at about 1% of the rate at which it catalyzes nonoxidative dopa decarboxylation. The mutant Y332F enzyme, however, catalyzes stoichiometric conversion of dopa to 3,4-dihydroxyphenylacetaldehyde, suggesting that even minor structural changes may alter or initiate paracatalytic reactions catalyzed by certain enzymes. Carbanions generated by several thiamine diphosphate (ThDP)-dependent enzymes react with different electrophiles, transforming some xenobiotics and endogenous compounds into potentially biologically hazardous products. The detrimental effects of paracatalytic reactions may be greatly increased by cellular compartmentation of enzymes and intermediates. For example, in two of the the three multienzyme complexes involved in oxidative α-keto acid decarboxylation, paracatalytic reactions of the third component inactivate the first carbanion-generating component. In this review we provide an outline of carbanion-generating enzymes known to catalyze paracatalytic reactions. We also discuss the potential of some of these reactions to contribute to irreversible damage in cancer and neurodegeneration through disease-induced alterations in the metabolic state and/or protein structure.
Journal of Biological Chemistry, 2006
We have isolated and characterized Petunia hybrida cv. Mitchell phenylacetaldehyde synthase (PAAS... more We have isolated and characterized Petunia hybrida cv. Mitchell phenylacetaldehyde synthase (PAAS), which catalyzes the formation of phenylacetaldehyde, a constituent of floral scent. PAAS is a cytosolic homotetrameric enzyme that belongs to group II pyridoxal 5-phosphate-dependent amino-acid decarboxylases and shares extensive amino acid identity (ϳ65%) with plant L-tyrosine/3,4-dihydroxy-L-phenylalanine and L-tryptophan decarboxylases. It displays a strict specificity for phenylalanine with an apparent K m of 1.2 mM. PAAS is a bifunctional enzyme that catalyzes the unprecedented efficient coupling of phenylalanine decarboxylation to oxidation, generating phenylacetaldehyde, CO 2 , ammonia, and hydrogen peroxide in stoichiometric amounts.
Cancers
Protein disulfide isomerase (PDI) is the endoplasmic reticulum (ER)’s most abundant and essential... more Protein disulfide isomerase (PDI) is the endoplasmic reticulum (ER)’s most abundant and essential enzyme and serves as the primary catalyst for protein folding. Due to its apparent role in supporting the rapid proliferation of cancer cells, the selective blockade of PDI results in apoptosis through sustained activation of UPR pathways. The functions of PDI, especially in cancers, have been extensively studied over a decade, and recent research has explored the use of PDI inhibitors in the treatment of cancers but with focus areas of other cancers, such as brain or ovarian cancer. In this review, we discuss the roles of PDI members in breast cancer and PDI inhibitors used in breast cancer research. Additionally, a few PDI members may be suggested as potential molecular targets for highly metastatic breast cancers, such as TNBC, that require more attention in future research.
The Changhua Journal of Medicine, Jul 1, 2001
Primary cultured neurons are significantly damaged by brief exposure to 0.25mM glutamate (Glu). T... more Primary cultured neurons are significantly damaged by brief exposure to 0.25mM glutamate (Glu). The neuronal damage, as indicated by cell lysis, was not distinguishable until at least 6 to 8 hour after Glu exposure. Inclusion of taurine at 25mM in the extracellular medium reduced Glu-induced neuronal injury. The neuroprotective effect of taurine was not affected by the presence of taurine transport inhibitors, e.g. guanidinoethyl sulfonate (GES) and β-alanine, indicating that intracellular uptake of taurine is not necessary for the neuroprotection by taurine. The presence of 25mM taurine in the medium did not cause a significant change of total intracellular taurine level during Glutreatment. It also had little effect on Glu-induced cell swelling as indicated by [(superscript 3)H]taurine efflux. However, taurine exhibited a remarkable effect on Glu-induced elevation of intracellular calcium level [Ca(surperscript 2+)](subscript i). Therefore, we conclude that the neuroprotection of taurine against Glu-induced neurotoxicity observed in cultured neurons is primarily a result of reducing the level of [Ca(superscript 2+)](subscript i), rather than serving as an osmoregulator.
Kluwer Academic Publishers eBooks, 1990
Bioorganic Chemistry, Jun 1, 1980
ABSTRACT
Biochemical and Biophysical Research Communications, Jul 1, 1977
amino-acid oxidase with propargylglycine, in which both irreversible (Marcotte and Walsh, 1978a) ... more amino-acid oxidase with propargylglycine, in which both irreversible (Marcotte and Walsh, 1978a) and reversible (Marcotte and Walsh, 1978b) interactions are observed. This work has demonstrated that, when reaction between an enzyme and a substrate analogue results in release of a highly reactive product, it is necessary to characterize the pathway following the enzymatic step to determine if any species formed subsequently interacts with that enzyme or other enzymes in vivo.
Biomedicines, Jul 3, 2023
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
An iron containing superoxide dismutase from the cytosol of the thermoacidophilic crenarchaeon Su... more An iron containing superoxide dismutase from the cytosol of the thermoacidophilic crenarchaeon Sulfolobus acidocaldarius (DSM 639) has been purified to electrophoretic homogeneity. It comprises at least 11% of the cytosolic protein. The isolated protein consists of two identical subunits with an apparent molecular mass of 22.4 kDa. It contains one iron atom per dimer. The protein shows the typical EPR spectrum of a S = 3/2, rhombic high-spin iron center. It is extremely resistant against thermal and chemical denaturation. Simultaneous treatment with heat and detergent resulted in the conversion into a more active tetrameric form. Similar enzymes appear to be present in the cytosol of other members of the Sulfolobaceue. The dimeric form of the protein from S. acidoculdurius has been crystallized.
Biochemistry, Dec 26, 1978
amino-acid oxidase with propargylglycine, in which both irreversible (Marcotte and Walsh, 1978a) ... more amino-acid oxidase with propargylglycine, in which both irreversible (Marcotte and Walsh, 1978a) and reversible (Marcotte and Walsh, 1978b) interactions are observed. This work has demonstrated that, when reaction between an enzyme and a substrate analogue results in release of a highly reactive product, it is necessary to characterize the pathway following the enzymatic step to determine if any species formed subsequently interacts with that enzyme or other enzymes in vivo.
Journal of Bacteriology, 1979
An iron containing superoxide dismutase from the cytosol of the thermoacidophilic crenarchaeon Su... more An iron containing superoxide dismutase from the cytosol of the thermoacidophilic crenarchaeon Sulfolobus acidocaldarius (DSM 639) has been purified to electrophoretic homogeneity. It comprises at least 11% of the cytosolic protein. The isolated protein consists of two identical subunits with an apparent molecular mass of 22.4 kDa. It contains one iron atom per dimer. The protein shows the typical EPR spectrum of a S = 3/2, rhombic high-spin iron center. It is extremely resistant against thermal and chemical denaturation. Simultaneous treatment with heat and detergent resulted in the conversion into a more active tetrameric form. Similar enzymes appear to be present in the cytosol of other members of the Sulfolobaceue. The dimeric form of the protein from S. acidoculdurius has been crystallized.
Advances in Space Research, 1992
Springer eBooks, 1990
Enzy~at1c and model carboxylation and reduction reactions for carbon d10x1de ut1l1zat10n ! edited... more Enzy~at1c and model carboxylation and reduction reactions for carbon d10x1de ut1l1zat10n ! edited by M. Aresta and J.V. Schloss. p. cm.-(NATO ASI series. Series C. Mathemat1cal and physical sciences; vol. 314) papers from a NATO Advanced Study Institute summer school held June 17-28. 1989 1n Ginosa • Italy. flncludes bib I iographical references and 1noex.
Inflammopharmacology
Multiple nutritional deficiencies (MND) confound studies designed to assess the role of a single ... more Multiple nutritional deficiencies (MND) confound studies designed to assess the role of a single nutrient in contributing to the initiation and progression of disease states. Despite the perception of many healthcare practitioners, up to 25% of Americans are deficient in five-or-more essential nutrients. Stress associated with the COVID-19 pandemic further increases the prevalence of deficiency states. Viral infections compete for crucial nutrients with immune cells. Viral replication and proliferation of immunocompetent cells critical to the host response require these essential nutrients, including zinc. Clinical studies have linked levels of more than 22 different dietary components to the likelihood of COVID-19 infection and the severity of the disease. People at higher risk of infection due to MND are also more likely to have long-term sequelae, known as Long COVID. Keywords Multiple nutritional deficiencies • Lymphocyte proliferation assay • Myeloperoxidase • Glutathione peroxidase isozyme 4 • NADPH oxidase 2 Abbreviations MND Multiple nutritional deficiencies LPA Lymphocyte proliferation assay MPO Myeloperoxidase GPX4 Glutathione peroxidase isozyme 4 NOX2 NADPH oxidase 2
IDrugs : the investigational drugs journal, 1998
This symposium was organized by Dan Flynn (Monsanto Life Sciences, USA) and Timothy M Willson (Gl... more This symposium was organized by Dan Flynn (Monsanto Life Sciences, USA) and Timothy M Willson (Glaxo Wellcome, USA). PPARs (peroxisome proliferator-activated receptors), are nuclear hormone receptors that govern glucose and lipid homeostasis. There are several subtypes of receptors that share activation by unsaturated fatty acids and work in combination with retinoic acid receptors (RXR), which were a topic covered in an earlier symposium. Two classes of chemistry were discussed at the symposium: (i) thiazolidinediones, that interact directly with PPARs and alter lipid metabolism; and, (ii) benzothiepines or benzothiazepines, that inhibit the ileal bile acid transporter (IBAT) and reduce cholesterol levels by increasing bile acid excretion.
Advances in Enzymology - and Related Areas of Molecular Biology, 2011
I. Overview Enzymes that generate carbanionic intermediates often catalyze paracatalytic reaction... more I. Overview Enzymes that generate carbanionic intermediates often catalyze paracatalytic reactions with O 2 and other electrophiles not considered "normal" reactants. For example, pyridoxal 5′phosphate (PLP)-containing pig kidney dopa decarboxylase oxidizes dopamine with molecular O 2 to 3,4-dihydroxyphenylacetaldehyde at about 1% of the rate at which it catalyzes nonoxidative dopa decarboxylation. The mutant Y332F enzyme, however, catalyzes stoichiometric conversion of dopa to 3,4-dihydroxyphenylacetaldehyde, suggesting that even minor structural changes may alter or initiate paracatalytic reactions catalyzed by certain enzymes. Carbanions generated by several thiamine diphosphate (ThDP)-dependent enzymes react with different electrophiles, transforming some xenobiotics and endogenous compounds into potentially biologically hazardous products. The detrimental effects of paracatalytic reactions may be greatly increased by cellular compartmentation of enzymes and intermediates. For example, in two of the the three multienzyme complexes involved in oxidative α-keto acid decarboxylation, paracatalytic reactions of the third component inactivate the first carbanion-generating component. In this review we provide an outline of carbanion-generating enzymes known to catalyze paracatalytic reactions. We also discuss the potential of some of these reactions to contribute to irreversible damage in cancer and neurodegeneration through disease-induced alterations in the metabolic state and/or protein structure.
Journal of Biological Chemistry, 2006
We have isolated and characterized Petunia hybrida cv. Mitchell phenylacetaldehyde synthase (PAAS... more We have isolated and characterized Petunia hybrida cv. Mitchell phenylacetaldehyde synthase (PAAS), which catalyzes the formation of phenylacetaldehyde, a constituent of floral scent. PAAS is a cytosolic homotetrameric enzyme that belongs to group II pyridoxal 5-phosphate-dependent amino-acid decarboxylases and shares extensive amino acid identity (ϳ65%) with plant L-tyrosine/3,4-dihydroxy-L-phenylalanine and L-tryptophan decarboxylases. It displays a strict specificity for phenylalanine with an apparent K m of 1.2 mM. PAAS is a bifunctional enzyme that catalyzes the unprecedented efficient coupling of phenylalanine decarboxylation to oxidation, generating phenylacetaldehyde, CO 2 , ammonia, and hydrogen peroxide in stoichiometric amounts.
Cancers
Protein disulfide isomerase (PDI) is the endoplasmic reticulum (ER)’s most abundant and essential... more Protein disulfide isomerase (PDI) is the endoplasmic reticulum (ER)’s most abundant and essential enzyme and serves as the primary catalyst for protein folding. Due to its apparent role in supporting the rapid proliferation of cancer cells, the selective blockade of PDI results in apoptosis through sustained activation of UPR pathways. The functions of PDI, especially in cancers, have been extensively studied over a decade, and recent research has explored the use of PDI inhibitors in the treatment of cancers but with focus areas of other cancers, such as brain or ovarian cancer. In this review, we discuss the roles of PDI members in breast cancer and PDI inhibitors used in breast cancer research. Additionally, a few PDI members may be suggested as potential molecular targets for highly metastatic breast cancers, such as TNBC, that require more attention in future research.