Recently an enzyme that degrades a-1,3-D-glucosyl D-glucose
(nigerose, 4) was identified in Clostridium phytofermentans and
has been characterised as nigerose phosphorylase.44 a-1,3-Glucan
polymers are found in fungal cell walls45 and this is presumably
the source of the natural substrate for this enzyme. The enzyme
shows some activity towards kojibiose (2) as an acceptor and can
also transfer a single glucose residue onto some other monosaccharides
(Fig. 8).