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Lloyd Frick
University of North Carolina at Chapel Hill
9Publications
7H-index
279Citations
Publications 9
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#1Lloyd Frick (UNC: University of North Carolina at Chapel Hill)H-Index: 7
#2Charles C. Yang (UNC: University of North Carolina at Chapel Hill)H-Index: 5
Last.Richard WolfendenH-Index: 47
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Caracterisation de l'interaction de la cytidine desaminase bacterienne avec la pyrimidine-2-one ribonucleoside et la 5-fluoropyrimidine-2-one ribonucleoside. Ces deux composes sont des inhibiteurs competitifs de la cytidine desaminase de levure et de mammifere. Les mecanismes de liaison possibles pour ces inhibiteurs sont discutes. La pyrimidine-2-one ribonucleoside se lierait a l'enzyme sous forme de 3,4-dihydrouridine et par l'intermediaire de son atome d'oxygene
#1Charles W. Carter (UNC: University of North Carolina at Chapel Hill)H-Index: 7
#2Eric T. Baldwin (UNC: University of North Carolina at Chapel Hill)H-Index: 1
Last.Lloyd Frick (UNC: University of North Carolina at Chapel Hill)H-Index: 7
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Abstract Statistical design of crystallization experiments greatly reduces the amount of protein necessary to find conditions for crystal growth and leads naturally to a useful data base for improving crystallization conditions in cases where the initial trials do not produce adequate results. Although it is counterintuitive to vary simultaneously all the factors to be screened, this apparent loss of control over experimental parameters actually costs very little in terms of the statistical stre...
#1Lloyd Frick (UNC: University of North Carolina at Chapel Hill)H-Index: 7
#2John P. Mac Neela (UNC: University of North Carolina at Chapel Hill)H-Index: 1
Last.Richard Wolfenden (UNC: University of North Carolina at Chapel Hill)H-Index: 47
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Abstract Nonenzymatic rates of hydrolytic deamination of adenosine and cytidine by acids and bases analogous to side chains of naturally occurring amino acids are compared with the rates of uncatalyzed deamination in water and with the rates of the hydroxide- and hydrogen ion-catalyzed reactions. For adenosine, hydroxide ion is an effective catalyst, with a second-order rate constant of 7.5 × 10 −6 m −1 s −1 at 85°C and an energy of activation of 19.9 kcal/mol. Acid-catalyzed deamination of aden...
#1Lloyd Frick (UNC: University of North Carolina at Chapel Hill)H-Index: 7
#2Richard WolfendenH-Index: 47
Last.David C. Baker (UA: University of Alabama)H-Index: 19
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#1Richard Wolfenden (UNC: University of North Carolina at Chapel Hill)H-Index: 47
#2Lloyd Frick (UNC: University of North Carolina at Chapel Hill)H-Index: 7
The theory of absolute reaction rates implies that the grip of a catalyst on a substrate tightens with substrate activation, relaxing later as products are formed and released. Analogs that mimic different kinds of substrate activation can, through the structural details of their complexes with enzymes, indicate how active site residues are involved in the enhancement of reactions rates. In several cases, bonds involved in general acid-base catalysis have been identified tentatively; and recent ...
#1Lloyd Frick (UNC: University of North Carolina at Chapel Hill)H-Index: 7
#2Richard Wolfenden (UNC: University of North Carolina at Chapel Hill)H-Index: 47
Abstract α-Amino aldehydes and bestatin are found to be effective inhibitors of a cytosolic dipeptidase (rat testicular peptidase C), and a cytosolic tripeptidase (rat kidney peptidase B, EC 3.4.11.4), as well as cytosolic leucine aminopeptidase (pig kidney peptidase S, EC 3.4.11.1). Aldehyde hydrates and bestatin share a resemblance to intermediates that might be formed during direct attack by water on peptide substrates, affording a possible explanation for their tight binding. Alternatively, ...
#1Lloyd Frick (UNC: University of North Carolina at Chapel Hill)H-Index: 7
Abstract 1. 1. Five cytosolic di- and tripeptidases of the tuna, Katsuwonis pelamis , were isolated and characterized. 2. 2. Biochemical and electrophoretic properties were compared and used to unify the genetic (PEP A, B, D and S) and enzymatic (EC 3.4.14.11; EC 3.4.11.4; EC 3.4.13.9, and EC 3.4.11.1) nomenclatures. 3. 3. The enzymes studied are a heterogenous group and do not appear to be closely related, with the possible exception of PEP A and C. 4. 4. Properties of homologous pairs of enzym...
#1Lloyd Frick (UNC: University of North Carolina at Chapel Hill)H-Index: 7
Electrophoretic and immunological techniques have been used to analyze the cytosolic di- and tripeptidases of guinea pigs. In contrast to previous reports utilizing intestinal mucosa extracts, cavian peptidases were found to be similar to peptidases described in other mammals and in fishes. Earlier papers are in error owing to coelectrophoresis of enzymes and to impure enzyme preparations. Guinea pigs are unusual in that they appear to lack peptidase C.
#1Lloyd Frick (UNC: University of North Carolina at Chapel Hill)H-Index: 7
The cytosolic di- and tripeptidases of fish were studied in an electrophoretic phylogenetic survey that included elasmobranchs, a holostean, and teleosts. Antisera against four of the peptidases from tuna were raised in rabbits and used to establish homologies between the peptidases of tuna and other fish and between piscine PEP A, B, and S and corresponding enzymes of the higher vertebrates. Substrate specificities, tissue distributions, and electrophoretic mobilities were conserved during the ...
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