Synthesis and evaluation of an inhibitor of carboxypeptidase A with a K sub i value in the femtomolar range

Journal Article · Tue Aug 20 04:00:00 EDT 1991 · Biochemistry; (United States)

DOI:https://doi.org/10.1021/bi00247a011· OSTI ID:5702903

Kaplan, A P; Bartlett, P A ^[1]

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1. Univ. of California, Berkeley (United States)

Comparative studies among a series of tripeptide phosphonate inhibitors of the zinc peptidase carboxypeptidase A indicate that incorporation of the phosphonic acid analogue of valine at the P{sub 1} position results in significantly higher affinity than the glycine, alanine, or phenylalanine analogues. When applied to the tripeptide analogue Cbz-Phe-Val{sup p}-(O)Phe(ZFV{sup P}(O)F), determination of the inhibition constant K{sub i} was complicated by the very slow rate of dissociation. The rate of exchange of ({sup 3}H)ZFV{sup P}(O)F with enzyme-bound ({sup 14}C)ZFV{sup P}(O)F was followed for periods of 3-4 months to measure dissociation rate constants in the range of (1.7-4.4) X 10{sup {minus}9} s{sup {minus}1}, corresponding to half of 5-13 years. Although the on- and off-rate constants differ for different carboxypeptidase isozymes, their ratios, corresponding to the inhibition constants K{sub i}, are consistently in the range of 10-27 fM. Both the inhibition constants and the dissociation rate constants appear to be the lowest values yet determined for an enzyme-small inhibitor interaction.

• OSTI ID: 5702903
• Journal Information: Biochemistry; (United States), Journal Name: Biochemistry; (United States) Vol. 30:33; ISSN 0006-2960; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

550200* -- Biochemistry
59 BASIC BIOLOGICAL SCIENCES
AMINO ACIDS
BIOCHEMICAL REACTION KINETICS
BIOSYNTHESIS
CARBOXYLIC ACIDS
CARBOXYPEPTIDASES
ENZYME INHIBITORS
ENZYMES
ESTERS
HYDROGEN COMPOUNDS
HYDROLASES
ISOENZYMES
KINETICS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
PEPTIDE HYDROLASES
PHOSPHONIC ACID ESTERS
PROTEINS
REACTION KINETICS
SYNTHESIS
TRITIUM COMPOUNDS
VALINE