||Sousa, M. O; Miranda, T. L. S; Costa, E. B; Bittar, E. R; Santoro, M. M; Figueiredo, A. F. S.|
||Linear competitive inhibition of human tissue kallikrein by 4-aminobenzamidine and benzamidine and linear mixed inhibition by 4-nitroaniline and aniline|
||Braz. j. med. biol. res = Rev. bras. pesqui. méd. biol;34(1):35-44, Jan. 2001. tab, graf.
||Apresentado em: Annual Meeting of the Brazilian Society of Biochemistry and Molecular Biology, 28, Caxambu, May 22-25, 1999.
||FAPEMIG; . CNPq.
||Hydrolysis of D-valyl-L-leucyl-L-arginine p-nitroanilide (7.5-90.0 `M) by human tissue kallikrein (hK1) (4.58-5.27 nM) at pH 9.0 and 37ºC was studied in the absence and in the presence of increasing concentrations of 4-aminobenzamidine (96-576 `M), benzamidine (1.27-7.62 mM), 4-nitroaniline (16.5-66 `M) and aniline (20-50 mM). The kinetic parameters determined in the absence of inhibitors were: Km = 12.0 + or - 0.8 `M and k cat = 48.4 + or - 1.0 min-1. The data indicate that the inhibition of hK1 by 4-aminobenzamidine and benzamidine is linear competitive, while the inhibition by 4-nitroaniline and aniline is linear mixed, with the inhibitor being able to bind both to the free enzyme with a dissociation constant Ki yielding an EI complex, and to the ES complex with a dissociation constant Ki', yielding an ESI complex. The calculated Ki values for 4-aminobenzamidine, benzamidine, 4-nitroaniline and aniline were 146 + or - 10, 1,098 + or - 91, 38.6 + or - 5.2 and 37,340 + or - 5,400 `M, respectively. The calculated Ki' values for 4-nitroaniline and aniline were 289.3 + or - 92.8 and 310,500 + or - 38,600 `M, respectively. The fact that Ki'>Ki indicates that 4-nitroaniline and aniline bind to a second binding site in the enzyme with lower affinity than they bind to the active site. The data about the inhibition of hK1 by 4-aminobenzamidine and benzamidine help to explain previous observations that esters, anilides or chloromethyl ketone derivatives of Nalpha-substituted arginine are more sensitive substrates or inhibitors of hK1 than the corresponding lysine compounds|
||Compostos de Anilina/farmacologia|
Calicreínas Teciduais/antagonistas & inibidores
Sítios de Ligação
Inibidores da Tripsina/farmacologia
| Tipo de Publ:
||Research Support, Non-U.S. Gov't|
||BR1.1 - BIREME|