J. Masarova et al., Stability enhancement of Escherichia coli penicillin G acylase by glycosylation with yeast mannan, BIOT APP B, 34, 2001, pp. 127-133
Penicillin G acylase (PGA) from Escherichia coil was cross-linked with mann
an dialdehydes. Conjugates were prepared with molecular masses varying from
140 to 580 kDa and containing from 18 to 50% (w/w) saccharides, the values
depending on the reaction conditions (mannan/enzyme ratio), and by using m
annans with different degrees of oxidation and weight-average molecular mas
s (M-W). The pH- and thermostability of all preparations of glycosylated en
zyme were improved remarkably, whereby the influence of the character of th
e linked mannan dialdehyde, its content, as well as the molecular mass of p
repared glycoconjugates, on the stability of PGA, was evaluated. PGA glycos
ylated with the most oxidized mannan up to an Mw of 490 kDa, containing 41%
(w/w) saccharides, and retaining 90% of its original catalytic activity, s
howed the highest stability. The half-life of this PGA preparation increase
d significantly: 13-fold at pH 3, 7-fold at pH 10, and 3.5-fold at pH 8 (al
l at 37 degreesC), compared with the native enzyme. At higher temperatures
(50 degreesC) even more significant stabilization was evident, a 16-fold in
crease in half-life, from 18 min to 289 min, at pH 8, being measured.