Handbook of Size Exclusion Chromatography and Related ...

Figure 8 Linear and cubic increases due to single and triple stranded degradation.
(DP Norwood and WF Reed, unpublished results.)
chains (55). The upper left inset inFig. 9shows the action ofgalactosidase on the
GM, which is to strip off the galactose side chains. The signature for this type of
reaction was predicted to be (56)
Kc0
I(q, t) ¼
1þu(t)=3
Mt,0[fp þ(1 fp)exp( at)] 2þ2A2(t)c0 (20)
whereMt,0 isthetotalinitial polymer mass(¼ Mp þMs,0,whereMs,0 istheinitial
side chain mass), fp, is the initial fraction of mass in the backbone, and
u(t) ¼q 2 kS 2 l z(t) (21)
where kS 2 l z(t) is the mean square z-average radius of gyration. It is assumed that
the stripped side chains themselves scatter insignificantly compared to the
remaining backbone. The aboveform will hold for stripping side chains from any
polymer conformation, as long as u,1. For the case of stripping from an ideal
randomcoil(whichGMresembles),thenumerator1þu=3canbereplacedbyu=2
for the case where u.3.
The upper right inset to Fig. 9shows the reciprocal scattering signature
when the GM is exposed to mannanase, which can cleave the mannose backbone
thathasno“protection”bygalactosesidechains.Thesignaturecorrespondstothe
© 2004 by Marcel Dekker, Inc.