Cellobiose synthesis

Synthesis of Carba-maltose, Carba-isomaltose, Carba-cellobiose, and the Like 68... 

Such carba-disaccharides as validoxylamines A and B were synthesized as intermediary compounds in the total synthesis of validamycin antibiotics. Carba-disaccharides related to maltose, isomaltose, cellobiose, the trehaloses, and trehalosamine modifications have also been synthesized. 

A similar synthesis starting from the derivatives of maltose (55), lactose (46), and cellobiose (57) to give the L-asparagine derivatives 56,48, and 58, respectively, was accomplished by Dunstan and Hough.46... 

Langsford et al. reported that Cellulomonas fimi culture supernatants contained cellulase and proteinase activities, for which there appeared to be a relationship. Glucose repressed the synthesis of both activities and cellulose induced both 60), Adding cellulose to Cellulomonas sp. (NRCC 2406) cultures stimulated growth and improved production of cellulases 61). Optimum conditions for growth and cellulase production were pH 6.5 and 30 C. The addition of glucose in the presence of cellulose inhibited growth. Several species of Cellulomonas have cellobiose phosphorylase. 

The first group is comprised that of compounds which potentially could be degraded to form G-l-P by phosphorolysis by beta-linkage specific enzymes. They include IPTGlu, cellobiose, sophorose, salicin, and sucrose. Addition of these compounds, or exogenous G-l-P, to Solka Floe fermentations improved maximum cellulase yields from 171 to 309%, and the time period for enzyme synthesis was reduced from 95 to 59% compared with using Solka Floe only. 

R. S. Bhatt, L. Hough, and A. C. Richardson, The synthesis of 4, 6 -diacetamido-4, 6 -dideoxy-cellobiose hexa-acetate from lactose, Carbohydr. Res, 43 (1975) 57-67. 

S. Vonhoff, K. Piens, M. Pipelier, C. Braet, M. Claeyssens, and A. Vasella, Inhibition of cellobiohy-drolases from Trichoderma reesei. Synthesis and evaluation of some glucose-, cellobiose-, and cellotriose-derived hydroximolactams and imidazoles, Helv. Chim. Acta, 82 (1999) 963-980. 

When suitable strains to exploit natural substrates are available, their exploitation of cellulolytic substrates in pure culture could be restricted by the end-products of cellulolysis (cellobiose and glucose) repressing enzyme synthesis or inhibition/inactivation of further enzymic activity (Fig. 1). One of the simplest routes to relieve this difficulty was to use non-celluloly tic... 

The stimulation of the synthesis of the cellulase system of T. reesei QM 9414 by sophorose was established as shown by the results of experiments summarized in Table IV. Other than sophorose, of the glycosides and oligosaccharides tested, only lactose caused even a limited production of the enzymes of the cellulase system. Lactose is not as closely related structurally to sophorose as is, for example, the disaccharide laminaribiose it is more closely related structurally to cellobiose, which, despite being the major product of cellulose breakdown, does not promote enzyme production under the conditions of this experiment. It was noted that both intra- and extracellular constitutive enzyme levels produced by cells growing on glucose (or by resting cells without inducer, Table IV) are less than 0.5% of the fully induced levels and thus are negligible. 

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. 

K. Kurita, N. Hirakawa, and Y. Iwakura, Synthetic polymers containing sugar residues, 7. Synthesis and properties of polyurethanes from D-cellobiose and diisocyanates, Makromol. Chem., 181 (1980) 1861-1870. 

Barker et al.ls4 reported the enzymic synthesis of the pseudoaldo-biouronic acid, 2-G-M-n-glucopyranosyl-D-glucuronic acid. The synthesis of 4-0-/f-D-glucopyranosyl-D-glucuronic acid (67) by permanganate oxidation of l T A A -hepta-O-acetyb/f-cellobiose (66) was described,185 and 4-0-o -D-glucopyranosyl-D-glucuronic acid was similarly prepared.186... 

The treatment of cellobial with perbenzoic acid and water leads predominantly to 4-( 8-D-glucopyranosyl)-D-mannose.38 On the other hand, the treatment of hexaacetylcellobial in the same manner leads predominantly to cellobiose, which has been isolated as the octaacetyl derivative. Hexaacetylcellobial has also been made from the synthetically prepared epicellobiose, and the conversion of hexaacetylcellobial to cellobiose has completed the total synthesis of this important sugar.17... 

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