Dk. Watt et al., AGROBACTERIUM-TUMEFACIENS BETA-GLUCOSIDASE IS ALSO AN EFFECTIVE BETA-XYLOSIDASE, AND HAS A HIGH TRANSGLYCOSYLATION ACTIVITY IN THE PRESENCEOF ALCOHOLS, Biochimica et biophysica acta. Protein structure and molecular enzymology, 1385(1), 1998, pp. 78-88
Agrobacterium tumefaciens beta-glucosidase, Cbg1 was extensively chara
cterised and found to be a retaining aryl-glucosidase and an aryl-xylo
sidase. Cbg1s specificity for p-nitrophenyl beta-D-xylopyranoside was
73% that for p-nitrophenyl beta-D-glucopyranoside when measured by the
ratio k(cat)/K-m. The enzyme also hydrolysed p-nitrophenyl beta-D-fuc
opyranoside, and p-nitrophenyl beta-D-galactopyranoside with moderate
efficiency. The enzyme released only terminal glucose from p-nitrophen
yl beta-cellobioside and had a 20000-fold preference for its natural s
ubstrate coniferin over cellobiose as indicated by the ratio k(cat)/K-
m. The enzyme was activated in the presence of 20 mM l-propanol, l-but
anol, l-pentanol, 1-hexanol, 1-heptanol, and l-octanol. In the case of
butanol this activation was investigated and shown to be due to trans
glycosylation activity with over 80% of p-nitrophenyl beta-D-glucopyra
noside being converted to l-butyl beta-D-glucopyranoside in the presen
ce of Cbg1 and 100 mM I-butanol. (C) 1998 Elsevier Science B.V. All ri
ghts reserved.