Green tea polyphenols: Novel irreversible inhibitors of dopa decarboxylase

Citation
M. Bertoldi et al., Green tea polyphenols: Novel irreversible inhibitors of dopa decarboxylase, BIOC BIOP R, 284(1), 2001, pp. 90-93
Citations number
15
Categorie Soggetti
Biochemistry & Biophysics
Journal title
BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS
ISSN journal
0006291X → ACNP
Volume
284
Issue
1
Year of publication
2001
Pages
90 - 93
Database
ISI
SICI code
0006-291X(20010601)284:1<90:GTPNII>2.0.ZU;2-B
Abstract
The green tea gallocatechins, (-)-epigallocatechin-3-O-gallate (EGCG), and (-)-epigallocatechin (EGC) were found to be inhibitors of Dopa decarboxylas e (DDC). EG;CG; and EGC inactivate the enzyme in both a time- and concentra tion-dependent manner and exhibit saturation of the rate of inactivation at high concentrations, with efficiency of inactivation values (k(inact)/K-i) of 868 and 1511 M-1 min(-1), respectively. In contrast, gallic acid behave s as a weak inhibitor of DDC. Protection against inactivation by EGCG; and EG;C was observed in the presence of the active site-directed inhibitor D-D opa. Either EGCG or EGC induce changes in the absorbance and CD bands of th e visible spectrum of enzyme-bound PLP. Taken together, these findings indi cate the active site nature of the interaction of DDC with both polyphenols . On the basis of the properties of the EGCG-inactivated enzyme, it can be suggested that inactivation could be ascribed to a covalent modification of not yet identified residue(s) of the active site of DDC. (C) 2001 Academic Press.