Affordable Access

Publisher Website

Identification of Functional Cysteine Residues in Human Galactosyltransferase

Authors
Journal
Biochemical and Biophysical Research Communications
0006-291X
Publisher
Elsevier
Publication Date
Volume
204
Issue
2
Identifiers
DOI: 10.1006/bbrc.1994.2516
Disciplines
  • Biology

Abstract

Abstract The functions of the five cysteine residues in human galactosyltransferase were investigated using site-directed mutagenesis to determine the location of the disulfide bond as well as the role of the sulfhydryl groups. The enzyme remains active when three of its cysteine residues at positions 171, 264 and 340 are mutated to serine separately. However, enzymatic activity is lost when either cysteine-129 or cysteine-245 is replaced with serine. The loss of GT activity suggests that these two cysteine residues form a disulfide bond. The three active mutated enzymes were studied kinetically. The kinetic constants of the enzymes with cysteine-171 or cysteine-264 replaced with serine are not significantly different from those of GT that does not have these substitutions. When cysteine-340 was mutated, however, the kinetic constant for UDP-galactose increased about 30 fold, while that for N-acetylglucosamine and Mn 2+ remained unchanged. In addition, sulfhydryl inhibition studies reveal that cysteine-340 is the only cysteine residue that reacts with the sulfhydryl reagents. These results indicate that cysteine-340 may be involved in the binding of UDP-galactose.

There are no comments yet on this publication. Be the first to share your thoughts.

Statistics

Seen <100 times
0 Comments

More articles like this

Identification of functional cysteine residues in...

on Biochemical and Biophysical Re... Oct 28, 1994

Identification of key functional residues in the a...

on Journal of Biological Chemistr... Nov 26, 2010

Effect of multiple cysteine substitutions on the f...

on Drug metabolism and dispositio... July 2012

Identification of functionally important cysteine...

on Journal of biochemistry April 2001
More articles like this..