Transglycosylation products

The fact that transglycosylation products of one of the enzymic components of the cellulase system of T. reesei can stimulate the production of the system may be of great importance in elucidating the mechanisms of the processes involved in the biosynthesis of these enzymes. Sophorose may be an early transglycosylation product, whose... 

All naturally occurring fungal strains of Trichoderma require an inducer for cellulase synthesis. In the absence of an inducer such as cellulose, cellobiose (21,22), or sophorose (12,13,14,23), Trichoderma does not make any detectable cellulase complex enzymes. The true physiological inducer of cellulase is currently unknown. Insoluble cellulose is presumably not such an inducer since there is no way for the internal cell machinery to sense the presence of this insoluble material. However, a small transglycosylation product such as sophorose, 2-0-/ -glucopyranosyl-D-glucose, may well be the natural inducer. 

Dehydration Reactions. Detailed analysis of the pyrolysis tar as discussed previously (Figure 12 and Scheme 3) shows the presence of levoglucosan, its furanose isomer (1,6-anhydro-p-D-glucofuranose) and their transglycosylation products as the main components. In addition to these compounds, the pyrolyzate contains minor amounts of a variety of products formed from dehydration of the glucose units. The dehydration products detected include 3-deoxy-o-erythrohexo-sulose, 5-hydroxymethyl-2-furaldehyde, 2-furaldehyde (furfural), other furan derivatives, levoglucosenone (l,6-anhydro-3,4-dideoxy-P-D-glycerohex-3-enopyranos-2-ulose), l,5-anhydro-4-deoxy-D-hex-l-ene-3-ulose, and other pyran derivatives. The dehydration products are important as intermediate compounds in char formation. 

Fukunaga, Y., Miyata, T., Nakayasu, N., Mizutani, K., Kasai, R., and Tanaka, O. 1989. Enzymic transglycosylation products of stevioside Separation and sweetness-evaluation. Agnc. Biol. Chem. 53 1603-1607. 

If the substrates of a reaction are more reactive than the products, the transglycosylation product will be favoured. 

C,8H320,6 504.441 Constit. of honey. Transglycosylation product formed when cyclodextrin glyco-syltransferase from Bacillus megaterium strain 5 is grown in a kojibiose medium. Mg +162 (c, 0.5 in H2O). 

Figure 6. Interception of an a-glucosyl-enzyme intermediate by a glucoside to yield a cellobioside transglycosylation product. 

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