Xylanase A from the phytopathogenic bacteriumErwinia chrysanthemiis
classified as a glycoside hydrolase family 30 enzyme (previously in family 5)
and is specialized for degradation of glucuronoxylan. The recombinant
enzyme was crystallized with the aldotetraouronic acidb-D-xylopyranosyl-(1fi4)-[4-O-methyl-a-D-glucuronosyl-(1 fi2)]-b-D-xylopyranosyl-(1 fi4)-D-xylose as a ligand.
The mode of action of xylanase A from a phytopathogenic bacterium,
Erwinia chrysanthemi, classified in glycoside hydrolase family 5, was investi-gated on xylooligosaccharides and polysaccharides using TLC, MALDI-TOF MS and enzyme treatment with exoglycosidases.
Shikimate kinase was chosen as a convenient representative example of the subclass of a/b proteins with which to examine the mechanism of protein folding. In this paper we report on the refolding of the enzyme after denaturation in urea. As shown by the changes in secondary and tertiary structure monitored by far UV circular dichroism (CD) and ﬂuorescence, respectively, the enzyme was fully unfolded in 4 M urea. From an analysis of the unfolding curve in terms of the two-state model, the stability of the folded state could be estimated as 17 kJÆmol)1.