Wetzler C, Behrens U
Z Allg Mikrobiol. 1982;22(1):73-6. doi: 10.1002/jobm.3630220109.
After exhaustion of the C-source, terminating the accumulation of the extracellular polysaccharide, the excretion of the epimerase is increased, accordingly the moiety of guluronosyls of the alginate is augmented. Epimerization reactions with an epimerase preparation with commercial alginates from algae lead to higher conversion rates than with alginate from Azotobacter vinelandii. It is reasoned that the acetyl groups of bacterial alginate perform a steric hinderance. Because of the small amount of guluronosyls in Azotobacter alginate, these alginates do not form gels with Ca++.
在碳源耗尽后，细胞外多糖的积累终止，表异构酶的排泄增加，相应地，藻酸盐中古洛糖醛酸残基的部分增加。与来自藻类的商业藻酸盐的表异构酶制剂进行的表异构化反应比与来自棕色固氮菌的藻酸盐的反应导致更高的转化率。据推测，细菌藻酸盐的乙酰基起到空间位阻作用。由于棕色固氮菌藻酸盐中古洛糖醛酸残基的量少，这些藻酸盐不与Ca++形成凝胶。
