Kinetic mechanism of the inhibition of human urinary kallikrein by basic pancreatic trypsin inhibitor
Braz. j. med. biol. res
;
28(5): 505-12, May 1995. graf
Article
in English
| LILACS
| ID: lil-154871
RESUMO
Hydrolysis of D-valvyl-L-leucyl-L-arginine p-nitroanilide (D-Val-Leu-Arg-Nan) at five different concentration (10-20µM) by human urinary kallikrein was studied in the absence and in the presence of increasing concentrations of basic pancreatic trypsin inhibitor (BPTI) (1.35-9.15nM). The data indicate that the inhbition of human urinary kallikrein by BPTI is not a simple competitive inhibition as reported by others, but that it is a competitive inhibition of the parabolic type, with two inhibitor molecules binding to one enzyme molecule, with the formetion of a ternary enzymatic complex. Statistical analysis of the experimental data supports the kinetic model proposed. The calculated values of the constants Ki and Kii were 16.20 nM and 1.10 nM, repectively. It is noteworthy that the Kii < Ki, i.e., the second BPTI molecule binds to the enzyme with a larger affinity suggesting that this second binding site was probably created or positively modulated as a consequence of the binding of the first BPTI molecule
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Index:
LILACS (Americas)
Main subject:
Kallikreins
/
Aprotinin
Type of study:
Diagnostic study
Limits:
Humans
/
Male
Language:
English
Journal:
Braz. j. med. biol. res
Journal subject:
Biology
/
Medicine
Year:
1995
Type:
Article
/
Congress and conference
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