Substrate and inhibitor studies on proteinase 3
C M Kam1, J E Kerrigan, K M Dolman
1School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta 30332.
FEBS Letters
|February 3, 1992
Summary
Researchers identified optimal peptide thioester substrates for human proteinase 3, with Boc-Ala-Ala-Nva-SBzl showing the highest activity. Potent isocoumarin inhibitors were also discovered, though less effective against proteinase 3 than human neutrophil elastase.
Area of Science:
- Biochemistry
- Enzymology
- Pharmacology
Background:
- Human proteinase 3 is a key enzyme implicated in various physiological and pathological processes.
- Understanding its substrate specificity and inhibition is crucial for therapeutic development.
Purpose of the Study:
- To identify effective substrates for human proteinase 3.
- To discover and characterize potent inhibitors of human proteinase 3.
- To compare the inhibitory potency against proteinase 3 and human neutrophil elastase (HNE).
Main Methods:
- Enzyme kinetics assays were performed using various amino acid and peptide thioesters as substrates.
- Inhibition assays were conducted using substituted isocoumarins, peptide phosphonates, and chloromethyl ketones.
- Kinetic parameters (kcat/Km) for substrates and inhibition constants (kobs/[I]) were determined.
Main Results:
- Boc-Ala-Ala-Nva-SBzl was identified as the best substrate for proteinase 3, exhibiting a kcat/Km of 1.0 x 10(6) M-1.s-1.
- Several substituted isocoumarins, including 7-amino-4-chloro-3-(2-bromoethoxy)isocoumarin and 3,4-dichloroisocoumarin (DCI), demonstrated potent inhibition.
- Inhibitors were generally 1-2 orders of magnitude less potent against proteinase 3 compared to human neutrophil elastase.
Conclusions:
- Peptide thioesters, particularly Boc-Ala-Ala-Nva-SBzl, are suitable substrates for studying human proteinase 3.
- Substituted isocoumarins represent a promising class of inhibitors for proteinase 3.
- Differential inhibition potency highlights the distinct active site characteristics of proteinase 3 and HNE.
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