Frank Torre - Academia.edu (original) (raw)

Papers by Frank Torre

$Research paper thumbnail of Temperature dependence of the isotopic liquid-vapor fractionation factor for nitric oxide$

The Journal of Chemical Physics, 1974

The 15N/14N isotope fractionation factor between NO liquid and vapor has been determined in the t... more The 15N/14N isotope fractionation factor between NO liquid and vapor has been determined in the temperature range 110-173°K. The results are in good agreement with the isotopic vapor pressure data of Clusius et al., which cover the range 110-121°K. The isotope fractionation data follow the T-2 law up to 135°K. A refinement of the T-2 law analysis of the isotopic vapor pressure data given by Bigeleisen in 1960 has been carried out by the harmonic oscillator cell model to include T-1 and T0 terms. It is shown that the T-2 terms from the dimerization of the monomer in the liquid and the hindered translation and rotations of the dimer dominate the isotope fractionation factor. The falloff from the T-2 law for the liquid-vapor fractionation factor in NO is steeper than in argon. This is reconciled with the dissociation of the dimer in the liquid and the association of the monomer in the vapor at high temperatures.

Journal of Chemical Education, 2002

... Where Are We? And, Where Are We Going? MR Malachowski and NE Levinger, Organizers John G. Ste... more ... Where Are We? And, Where Are We Going? MR Malachowski and NE Levinger, Organizers John G. Stevens, Organizer, Presiding Cosponsored by Council on Undergraduate Research and SOCED. After three to four decades of the development of ...

Journal of Chemical Education, 2007

... A Journal sympo-sium will follow all day Monday. ... and Chemistry for General Students Basud... more ... A Journal sympo-sium will follow all day Monday. ... and Chemistry for General Students Basudeb DasSarma and Conrad Bergo, Organizers Basudeb DasSarma, Presiding Post ... chemistry is introduced in many tiers general chemistry for science, engineering, and medicine ...

Journal of Chemical Education, 2008

... Afternoon A. Demonstrating Chemical Laws and Principles, Noon William C. Deese and John J. Fo... more ... Afternoon A. Demonstrating Chemical Laws and Principles, Noon William C. Deese and John J. Fortman, Organizers, Presiding ... Thursday, March 27 Morning A. Alternative Assignments: Assessment and Evaluation Debra Bautista, Organizer, Presiding Abby Parrill-Baker ...

Journal of Chemical Education, 2008

Journal of Chemical Education, 1988

ABSTRACT An engaging laboratory activity that can be completed in four hours. This lab has applic... more ABSTRACT An engaging laboratory activity that can be completed in four hours. This lab has applications to taxonomy and evolution. Keywords (Audience): Upper-Division UndergraduateKeywords (Domain): BiochemistryKeywords (Pedagogy): Hands-On Learning / ManipulativesKeywords (Subject): Electrophoresis

Journal of Chemical Education, 2009

CHED technical sessions will be in the Clarion Hotel, 616 Convention Way; morning sessions will... more CHED technical sessions will be in the Clarion Hotel, 616 Convention Way; morning sessions will begin at 8:30 am and afternoon sessions at 1:30 pm unless otherwise noted here or in the final program. Tickets to the CHED dinner (Saturday evening, March 27; event #101, $55) ...

Biochemistry, 1992

Aminopeptidases catalyze the hydrolysis of amino acid residues from the amino terminus of peptide... more Aminopeptidases catalyze the hydrolysis of amino acid residues from the amino terminus of peptide substrates. They are found in most cells and tissues, and their activity has been implicated in myriad fundamental biochemical and physiological processes. Nevertheless, little is known about the structure of the aminopeptidase active sites. Beef lens leucine aminopeptidase (blLAP) can be considered prototypical of many enzymes in this family of peptidases. Bestatin, [(2S,3R)-(3-amino-2-hydroxy-4-phenyl-butanoyl)-L-leucine] is a nonhydrolyzable substrate analogue of a peptide, PheLeu, which is rapidly cleaved by blLAP. Bestatin incorporates elements of the putative tetrahedral intermediate, and this results in a greater than 10(5)-fold enhancement of binding relative to analogous peptides. Bestatin is the most tightly bound inhibitor of many aminopeptidases. Bestatin was successively converted to nitrobestatin, p-aminobestatin, [3H]-p-aminobestatin, and finally [3H]-p-azidobestatin (pAB). Like bestatin, pAB is a slow binding inhibitor of LAP (Ki*, the dissociation constant for the final complex, = approximately 4 x 10(-9); Ki, the dissociation constant for the initial collision complex, = approximately 10(-8). The t1/2 for binding of 2 x 10(-8) M and 8 x 10(-8) M bestatin are approximately 60 min and approximately 38 min, respectively. pAB, nitrobestatin, bestatin, and physiological peptides appear to bind in the same site, the first three with similar avidity. In the dark, pAB and bestatin protect low concentrations of the enzyme against inactivation upon extensive dialysis. The t1/2 for photoactivation of pAB is approximately 3 s. Irradiation of blLAP for such short periods of time resulted in insignificant change in activity. blLAP which was placed in 254-nm light in the presence of pAB was inactivated significantly. Treatment of photolabeled blLAP with trypsin produces only two peptides. Autoradiography and scintillation counting indicate that the active site is in the peptide which includes residues 138-487. Treatment of the same blLAP with hydroxylamine produces two different peptides, with the active site in the peptide 323-487. This indicates that the active site is in the carboxyl-terminal one-third of the protomer. It is likely that this photoaffinity label will be useful in identifying active sites in other aminopeptidases as well.

Biochemistry, 1993

Aminopeptidases catalyze the hydrolysis of amino acid residues from the amino terminus of peptide... more Aminopeptidases catalyze the hydrolysis of amino acid residues from the amino terminus of peptide substrates. Their activity has been implicated in myriad fundamental biochemical and physiological processes, and alterations in aminopeptidase activity have been correlated with a variety of pathologies. Nevertheless, information about this group of proteases is less well developed. Bovine lens leucine aminopeptidase (blLAP) can be considered prototypical of many enzymes in this family of peptidases. It shows common features of (1) requiring divalent metal ions for activity, (2) having a relatively large size, and (3) having slow, relatively tight binding of bestatin, a transition-state analog of the substrate PheLeu. Bovine lens LAP is the only bestatin-inhibitable aminopeptidase for which structural and mechanistic data are available. However, full exploitation of these data required knowledge of the number of inhibitor molecules bound per subunit. Independent direct binding experiments and kinetic determinations indicate that one bestatin is bound per subunit in blLAP. Ki and Ki* for formation of the initial and final complexes are approximately 1.1 x 10(-7) and 1.3 x 10(-9) M, respectively. The mode of binding is slow and competitive. The t1/2 for formation and deformation of the final enzyme-inhibitor complex is approximately 30 and 22 min, respectively, with 10(-8) M bestatin. To perform these measures, a new assay using physiological peptides (LeuGlyGly) as substrate was adapted. Taken together with prior NMR, photoaffinity labeling, and crystallographic data, these binding data allow us to propose a mechanism of the blLAP-catalyzed hydrolysis of peptides.

Journal of Chemical Education, 1998

For those of us who had not been to Boston since the last ACS meeting it was surprising to see ho... more For those of us who had not been to Boston since the last ACS meeting it was surprising to see how vibrant the city was. The shops, restaurants, parks, and other attractions throughout the large inner city area made the meeting most enjoyable. Again, our banquet cruise of the harbor was blessed with excellent weather. The ship went out far

$Research paper thumbnail of Temperature dependence of the isotopic liquid-vapor fractionation factor for nitric oxide$

The Journal of Chemical Physics, 1974

Journal of Chemical Education, 2002

Journal of Chemical Education, 2007

Journal of Chemical Education, 2008

Journal of Chemical Education, 1988

Journal of Chemical Education, 2009

Biochemistry, 1992

Biochemistry, 1993

Aminopeptidases catalyze the hydrolysis of amino acid residues from the amino terminus of peptide... more Aminopeptidases catalyze the hydrolysis of amino acid residues from the amino terminus of peptide substrates. Their activity has been implicated in myriad fundamental biochemical and physiological processes, and alterations in aminopeptidase activity have been correlated with a variety of pathologies. Nevertheless, information about this group of proteases is less well developed. Bovine lens leucine aminopeptidase (blLAP) can be considered prototypical of many enzymes in this family of peptidases. It shows common features of (1) requiring divalent metal ions for activity, (2) having a relatively large size, and (3) having slow, relatively tight binding of bestatin, a transition-state analog of the substrate PheLeu. Bovine lens LAP is the only bestatin-inhibitable aminopeptidase for which structural and mechanistic data are available. However, full exploitation of these data required knowledge of the number of inhibitor molecules bound per subunit. Independent direct binding experiments and kinetic determinations indicate that one bestatin is bound per subunit in blLAP. Ki and Ki* for formation of the initial and final complexes are approximately 1.1 x 10(-7) and 1.3 x 10(-9) M, respectively. The mode of binding is slow and competitive. The t1/2 for formation and deformation of the final enzyme-inhibitor complex is approximately 30 and 22 min, respectively, with 10(-8) M bestatin. To perform these measures, a new assay using physiological peptides (LeuGlyGly) as substrate was adapted. Taken together with prior NMR, photoaffinity labeling, and crystallographic data, these binding data allow us to propose a mechanism of the blLAP-catalyzed hydrolysis of peptides.

Journal of Chemical Education, 1998