INVESTIGADORES
IGLESIAS Alberto Alvaro
artículos
Título:
Involvement of Thiol Groups in the Activity of Phosphoenolpyruvate Carboxylase from Maize Leaves
Autor/es:
A.A. IGLESIAS, C.S. ANDREO
Revista:
PHOTOSYNTHESIS RESEARCH
Referencias:
Año: 1984 vol. 5 p. 215 - 226
ISSN:
0166-8595
Resumen:
Abstract Purified
maize leaf phosphoenolpyruvate carboxylase (EC 4.1.1.31) was completely
inactivated by several thiol-modifying reagents, including, CuCl2, CdCl2 and N-ethylmaleimide. The inactivation by CuCl2 could be reversed by dithiothreitol, suggesting the involvement of vicinal dithiols in the inactivation process.
Complete inactivation of phosphoenolpyruvate carboxylase was correlated with the incorporation of two mol (3H)N-ethylmaleimide
per 100-kilodalton subunit. The total protection of the enzyme against
N-ethylmaleimide inactivation afforded by the substrate,
phosphoenolpyruvate, was correlated with the protection of one mol (3H)N-ethylmaleimide reactive residue per mol subunit.
The
complete inactivation of phosphoenolpyruvate carboxylase by
N-ethylmaleimide and the protection afforded by phosphoenolpyruvate
against modification suggest the presence of an essential cysteine
residue in the catalytic site of the C4 leaf enzyme.
Key words Cysteine modification - Maize leaf - Phosphoenolpyruvate carboxylase
Abbreviations PEP,
phosphoenolpyruvate
- Mops,
4-morpholinepropanesulphonic acid