Handbook of Size Exclusion Chromatography and Related ...

Figure 9 Upper left inset shows random stripping of the galactose side chains of a
galactomannan by galactosidase, according to Eq. (20). The right upper inset is the action of
mannase, which cleaves only mannose backbone sites unprotected by galactose. The main
figure shows simultaneous stripping of the side chains and backbone degradation, caused by
mixing the enzymes, according to Eqs. (22) and (23). (From Ref. 55.)
case when the number of bonds cleaved is of the order of the number of cleavable
bonds. The experiments revealed that an average of about three sequential
mannoses with no galactose side chains was necessary for mannanase to act. The
plateau reached in this figure corresponds to the residual scattering from the GM
fragments, which cannot be further digested because of galactose side chain
protection.
The main portion of Fig. 9 shows the effect of treating GM with
both mannanase and galactosidase simultaneously. Instead of reaching a plateau,
the degradation continues as galactosidase continues to strip side chains from the
GM fragments, allowing the mannanase to digest the GM backbone beyond what
it could when no galactose was stripped. The light scattering signature describing
this reaction is
Kc0
I(q, t) ¼
1
[ fp þ (1 fp) exp( at)] 2
© 2004 by Marcel Dekker, Inc.
1
2Mn,0
þ gq2
2
þ R(t)
2 þ 2A2,0c0 (22)