Glucan, yeast

Consistent with the above observations, the immunoactive glucans such as curdlan (9), lentinan (10), scleroglucan (11), schizophyllan (12) and yeast glucan (13) share a common p-D(l-3)-linked glucopyronosyl backbone. Some of these polymers also contain p-D(l-6)-linked glucopyranosyl branches through the 3,6-di-O-substituted C-6 atom of the backbone residues. 

Figure 2 compares the conformational transition curves of wild-type yeast glucan (branch frequency = 0.20) and PGG (branch frequency = 0.50). Wild-type yeast glucan required approximately 0.1M NaOH to disrupt the triple helical conformation, whereas this transition is observed at approximately 0.04 M NaOH with PGG. This trend is consistent with the observation that curdlan, an entirely linear p-D(l-3)-linked glucan, requires approximately 0.25M NaOH to disrupt the ordered conformation (76). Hence, it is concluded that the highly branched PGG molecules only form weak inter-chain associations resulting in the formation of predominantly single-helical zones. 

Figure 2 Effect of branch frequency on glucan conformation. Conformational characterization of glucans was carried out as described in the experimental section. Curdlan is a linear p(l-3)linked glucan Yeast glucan has a 30% P(l-6) branch frequency and PGG-R glucan has a 50% p(l-6) branch frequency. The Congo Red-single/triple helix complex absorption maxima are indicated.

Treatment of cell suspension cultures of T. rugosum with a yeast glucan elicitor induced the production of tyrosine decarboxylase in the late exponential and early stationary growth phases of the cells. Tyrosine decarboxylase has been suggested as the key enzyme between primary and secondary metabolism in the biosynthesis of norlaudanosoline-derived alkaloids, and a good correlation between induced tyrosine decarboxylase activity and berberine biosynthesis has been established [163]. 

Treatment of mice with lentlnan, pachymaran, carboxymethylpachymaran and hydroxyethylpachymaran B, but not with pachyman and hydroxyethylpach3nnan A, caused host-mediated regression of transplanted sarcoma 180. Also, lentlnan was reported to inhibit the growth of transplanted methylcholanthrene-lnduced fibrosarcoma. However, the substances were ineffective in ALS-treated or neonatally thymectomized mice, apparently in marked difference to what has been reported of yeast-glucan.87 Again in con-... 

Jamas, S., C.-K. Rha, A.J. Sinskey, "Directed biosynthesis of yeast glucans with known structure-function properties", paper presented at the ACS 190th Annual Meeting, Chicago, IL, September 9-13, 1985. 

First, by using alkali-insoluble glucan rather than cell walls as enzyme inducer, enzyme purification was greatly facilitated since yeast mannan (which is not attacked by B. circulans) does not accumulate as a very viscous component in concentrated crude enzyme solutions to be applied to chromatography columns. Yeast glucan is at least as effective as an enzyme inducer as are yeast cell walls. 

Yeast Glucan Debranching Enzymes. Rombouts and Phaff (95) postulated that the lytic / -( - 6)-glucanase which they purified from... 

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