type	Journal Article
authors	Claus, M.T.; Zocher, G.E.; Maier, T.H.; Schulz, G.E.
title	Structure of the O-Acetylserine Sulfhydrylase Isoenzyme CysM from Escherichia coli
journal	Biochemistry
Activity	2.5.1.47
Family	2.5.1.47
sel	selected
ui	68098346
year	(2005)
volume	44
number	24
pages	8620-6.
keywords	Adenosine Triphosphate
abstract	The enzyme O-acetylserine sulfhydrylase participates in the biosynthesis of l-cysteine in bacteria and plants. The structure of isoenzyme B (CysM) from Escherichia coli was established in a hexagonal crystal form at 2.7 A resolution (wild-type) and in a merohedrally twinned tetragonal crystal form at 2.1 A resolution (surface mutant). Structural superpositions revealed the variations with respect to isoenzyme A (CysK) and explained the different substrate specificities. A geometric model of the reaction catalyzed by CysM is proposed. Both isoenzymes are used for the production of l-amino acid derivatives as building blocks for the synthesis of peptides and peptidomimetic drugs. Since the structure of CysM revealed a remarkable main chain variation at the active center, it constitutes a further starting point for engineering mutants with novel substrate specificities.
last changed	2007/10/18 12:51