Structure and mechanism of an ADP-glucose phosphorylase from Arabidopsis thaliana.

The X-ray crystal structure of the At5g18200.1 protein has been determined to a nominal resolution of 2.30 A.

The mechanism of action of the fragile histidine triad, Fhit: isolation of a covalent adenylyl enzyme and chemical rescue of H96G-Fhit.

The human fragile histidine triad protein Fhit catalyzes the Mg(2+)-dependent hydrolysis of P(1)-5'-O-adenosine-P(3)-5'-O-adenosine triphosphate, Ap(3)A, to AMP and ADP. The reaction is thought to follow a two-step mechanism, in which the complex of Ap(3)A and Mg(2+) reacts in the first step with His96 of the enzyme to form a covalent Fhit-AMP intermediate and release MgADP. In the second step, the intermediate Fhit-AMP undergoes hydrolysis to AMP and Fhit.

Galactose mutarotase: pH dependence of enzymatic mutarotation.

Here we report pH dependence of kinetic parameters for the mutarotation of alpha-D-glucose catalyzed by galactose mutarotase (GalM) from Escherichia coli. The values of k(cat) and k(cat)/K(m) for the mutarotation of alpha-D-galactose were found to be 1.84 x 10(4) s(-1) and 4.