1l7k
From Proteopedia
|
x-ray structure of galactose mutarotase from Lactococcus lactis complexed with galactose
Overview
Galactose mutarotase plays a key role in normal galactose metabolism by, catalyzing the interconversion of beta-D-galactose and alpha-D-galactose., Here we describe the three-dimensional architecture of galactose, mutarotase from Lactococcus lactis determined to 1.9-A resolution. Each, subunit of the dimeric enzyme displays a distinctive beta-sandwich motif., This tertiary structural element was first identified in, beta-galactosidase and subsequently observed in copper amine oxidase, hyaluronate lyase, chondroitinase, and maltose phosphorylase. Two, cis-peptides are found in each subunit, namely Pro(67) and Lys(136). The, active site is positioned in a rather open cleft, and the electron density, corresponding to the bound galactose unequivocally demonstrates that both, anomers of the substrate are present in the crystalline enzyme. Those, residues responsible for anchoring the sugar to the protein include, Arg(71), His(96), His(170), Asp(243), and Glu(304). Both His(96) and, His(170) are strictly conserved among mutarotase amino acid sequences, determined thus far. The imidazole nitrogens of these residues are located, within hydrogen bonding distance to the C-5 oxygen of galactose., Strikingly, the carboxylate group of Glu(304) is situated at approximately, 2.7 A from the 1'-hydroxyl group of galactose, thereby suggesting its, possible role as a general acid/base group.
About this Structure
1L7K is a Single protein structure of sequence from Lactococcus lactis with GLA and NA as ligands. Active as Aldose 1-epimerase, with EC number 5.1.3.3 Full crystallographic information is available from OCA.
Reference
High resolution X-ray structure of galactose mutarotase from Lactococcus lactis., Thoden JB, Holden HM, J Biol Chem. 2002 Jun 7;277(23):20854-61. Epub 2002 Mar 20. PMID:11907040
Page seeded by OCA on Sun Nov 25 02:36:15 2007
