Interaction of aspartate aminotransferase with mercurochrome. Relationship of an exposed thiol group of the enzyme to the active centre.
Biochem J
; 167(1): 53-63, 1977 Oct 01.
Article
en En
| MEDLINE
| ID: mdl-73375
ABSTRACT
Mercurochrome strongly inhibits aspartate transaminase and 2,3-dicarboxyethylated aspartate transaminase. The native enzyme exhibits a biphasic time-course of inactivation by mercurochrome with second-order rate constants 1.62 x 10(4) M-1 - min-1 and 2.15 x 10(3) M-1 - min-1, whereas the modified enzyme is inactivated more slowly (second-order rate constant 6.1 x 10(2) M-1 - min-1) under the same conditions. The inhibitor inactivates native and modified enzyme in the absence as well as in the presence of substrates. Mercurochrome-transaminase interaction is accompanied by a red shift in the absorption maximum of the fluorochrome of about 10 nm. Difference spectra of the mercurochrome-enzyme system versus mercurochrome, compared with analogous spectra of mercurochrome-ethanol, revealed that the spectral shifts recorded during mercurochrome-transaminase interaction are similar to those that occur when mercurochrome is dissolved in non-polar solvents. Studies of mercurochrome complexes with native or modified transaminase, isolated by chromatography on Sephadex G-25, revealed that native transaminase is able to conjugate with four mercurochrome molecules per molecule, but the modified enzyme is able to conjugate with only two mercurochrome molecules per molecule.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Aspartato Aminotransferasas
/
Fluoresceínas
/
Merbromina
Límite:
Animals
Idioma:
En
Revista:
Biochem J
Año:
1977
Tipo del documento:
Article