Identification of the reactive cysteine residues in oligopeptidase B from Trypanosoma brucei.
Oligopeptidase B (OpdB) from Trypanosoma brucei is a candidate therapeutic target in African trypanosomiasis. OpdB is an atypical serine peptidase, since activity is inhibited by thiol-blocking reagents and enhanced by reducing agents. We have identified C256 as the reactive cysteine residue that mediates OpdB inhibition by N-ethylmaleimide and iodoacetic acid. Modeling studies suggest that C256 adducts occlude the P(1) substrate-binding site, preventing substrate binding. We further demonstrate that C559 and C597 are responsible for the thiol-enhancement of OpdB activity. These studies may facilitate the development of specific OpdB inhibitors with therapeutic potential, by exploiting these unique properties of this enzyme.
Morty
Rory E
RE
Department of Internal Medicine, University of Giessen School of Medicine, Aulweg 123 (Room 6-11), D-35392 Giessen, Germany. rory.morty@inmere.med.uni-giessen.de
Shih
Angela Y
AY
Fülöp
Vilmos
V
Andrews
Norma W
NW
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003545:Cysteine / Q000378:metabolism*; D017931:DNA Primers; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D017386:Sequence Homology, Amino Acid; D012697:Serine Endopeptidases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014346:Trypanosoma brucei brucei / Q000201:enzymology*
D017931:DNA Primers; D012697:Serine Endopeptidases; C090703:oligopeptidase B; D003545:Cysteine