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Lloyd Frick
University of North Carolina at Chapel Hill
EnzymeChemistryBiochemistryDipeptidaseCytosol
9Publications
7H-index
285Citations
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Publications 13
Newest
#1Nancy Cheng (UNC: University of North Carolina at Chapel Hill)H-Index: 11
#2Melissa A. Porter (UNC: University of North Carolina at Chapel Hill)H-Index: 3
Last. William P. Janzen (UNC: University of North Carolina at Chapel Hill)H-Index: 27
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The tendency for mycobacteria to aggregate poses a challenge for their use in microplate based assays. Good dispersions have been difficult to achieve in high-throughput screening (HTS) assays used in the search for novel antibacterial drugs to treat tuberculosis and other related diseases. Here we describe a method using filtration to overcome the problem of variability resulting from aggregation of mycobacteria. This method consistently yielded higher reproducibility and lower variability than...
7 CitationsSource
#1Nancy ChengH-Index: 11
#2Barbara M. MerrillH-Index: 18
Last. Phillip A. FurmanH-Index: 31
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We have utilized UV-induced cross-lining of [methyl- 3 H]dTTP to identify the nucleotide binding site on heterodimeric HIV-1 reverse transcriptase (RT). RT was derivatized by irradiating a solution containing [methyl- 3 H]dTTP and purified recombinant RT for 10 min. The UV-induced cross-linking reaction between dTTP and RT is linear with time of UV exposure up to 10 min, and it has been determined previously that dTTP cross-linking is half-maximal at 90 μM [Cheng, N., Painter, G. R., & Furmann, ...
19 CitationsSource
#1Lloyd FrickH-Index: 13
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ne (FIC), wereinvestigated inmaleCDrats. Plasma clearance of10mgofFTCperkgofbodyweight wasbiexponential inrats, with ahalf-life ataphase of4.7+ 1.1min(mean± standard deviation) andahalf-life at13 phase of44± 8.8min (n= 5).Thetotal bodyclearance ofFTCwas1.8± 0.1liters/h/kg, andtheoral bioavailablity was90%o ± 8%. Thevolume ofdistribution atsteady state (Vss) was1.5± 0.1liters/kg. Increasing thedoseto100mg/kg slowed clearance to1.5± 0.2liters/kg/h, lowered theVssto1.2± 0.2liters/kg, andreduced the...
#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
55 CitationsSource
#1Laurie Betts (UNC: University of North Carolina at Chapel Hill)H-Index: 18
#2L Frick (UNC: University of North Carolina at Chapel Hill)H-Index: 1
Last. Charles W. CarterH-Index: 33
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Abstract We have used an incomplete factorial design (Carter, C. W., and Carter, C. W., Jr. (1979) J. Biol. Chem. 254, 12219-12223) to find conditions for growing high quality crystals of Escherichia coli cytidine deaminase (EC 3.5.4.5). Crystals grow at pH 6.0 in hanging or sitting drops with either 1.6 M ammonium sulfate or 2.4-2.5 M sodium phosphate as precipitant. Both conditions produce crystals with identical morphologies and unit cell constants. The space group is P3(1)21 (or its enantiom...
18 Citations
#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...
75 CitationsSource
#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...
59 CitationsSource
#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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47 CitationsSource
#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 ...
8 CitationsSource
#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
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, inhibitor...
14 CitationsSource
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