Potent bivalent inhibition of human tryptase-beta by a synthetic inhibitor.
Biol Chem
; 384(12): 1605-11, 2003 Dec.
Article
en En
| MEDLINE
| ID: mdl-14719803
ABSTRACT
Human tryptase-beta (HTbeta) is a unique serine protease exhibiting a frame-like tetramer structure with four active sites directed toward a central pore. Potent inhibition of HTbeta has been attained using CRA-2059. This compound has two phenylguanidinium head groups connected via a linker capable of spanning between two active sites. The properties of the CRA-2059HTbeta interaction were defined in this study. Tight-binding reversible inhibition was observed with an inhibition constant (Ki) of 620 pM, an association rate constant of 7x10(7) M(-1) s(-1) and a relatively slow dissociation rate constant of 0.04 s(-1). Bivalent inhibition was demonstrated by displacement of p-aminobenzamidine from the primary specificity pocket with a stoichiometry, [CRA-2059]0/[HTbeta]0, of 0.5. The potency of the bivalent interaction was illustrated by CRA-2059 inhibition of HTbeta, 24% or 53% inhibited by pre-incubation with an irreversible inhibitor. Two interactions were observed consistent with mono- and bi-valent binding; the Ki value for bivalent inhibition was at least 10(4)-fold lower than that for monovalent inhibition. Comparison of the affinities of CRA-2059 and phenylguanidine for HTbeta finds an approximate doubling of the free energy change upon bivalent binding. This doubling suggests that the linker portion minimally hinders the binding of CRA-2059 to HTbeta. The potency of CRA-2059 is thus attributable to effective bivalent binding.
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Base de datos:
MEDLINE
Asunto principal:
Himecromona
/
Serina Endopeptidasas
/
Inhibidores de Serina Proteinasa
/
Dioxoles
/
Guanidinas
Límite:
Humans
Idioma:
En
Revista:
Biol Chem
Asunto de la revista:
BIOQUIMICA
Año:
2003
Tipo del documento:
Article
País de afiliación:
Estados Unidos