Activities | Families | Sequences | Fold types | References | Help
B6db references: ccarsds

type Journal Article
authors Yokoigawa, K.; Hirasawa, R.; Ueno, H.; Okubo, Y.; Umesako, S.; Soda, K.
title Gene cloning and characterization of alanine racemases from Shigella dysenteriae, Shigella boydii, Shigella flexneri, and Shigella sonnei
journal Biochem Biophys Res Commun
ui ccarSdS
year (2001)
volume 288
number 3
pages 676-84
keywords Alanine Racemase/*genetics/metabolism
abstract Alanine racemase genes (alr) from Shigella dysenteriae, Shigella boydii, Shigella flexneri, and Shigella sonnei were cloned and expressed in Escherichia coli JM109. All genes encoded a polypeptide of 359 amino acids, and showed more than 99% sequence identities with each other. In particular, the S. dysenteriae alr was identical with the S. flexneri alr. Differences in the amino acid sequences between the four Shigella enzymes were only two residues: Gly138 in S. dysenteriae and S. flexneri (Glu138 in the other) and Ile225 in S. sonnei (Thr225 in the other). The S. boydii enzyme was identical with the E. coli K12 alr enzyme. Each Shigella alr enzyme purified to homogeneity has an apparent molecular mass about 43,000 by SDS-gel electrophoresis, and about 46,000 by gel filtration. However, all enzymes showed an apparent molecular mass about 60,000 by gel filtration in the presence of a substrate, 0.1 M l-alanine. These results suggest that the Shigella alr enzymes having an ordinary monomeric structure interact with other monomer in the presence of the substrate. The enzymes were almost identical in the enzymological properties, and showed lower catalytic activities (about 210 units/mg) than those of homodimeric alanine racemases reported.
last changed 2008/05/15 18:51

B6db references