Yu L, Goldman R, Sullivan P, Walker G F, Fesik S W
Pharmaceutical Discovery Division, Abbott Labortories, Abbott Park, IL 60064.
J Biomol NMR. 1993 Jul;3(4):429-41. doi: 10.1007/BF00176009.
The structures of uniformly 13C-labeled beta-glucan octa- and undeca-oligosaccharides enzymatically prepared by the yeast cell wall glucanosyl transferase of Candida albicans were characterized by using a combination of HCCH-COSY, HCCH-TOCSY, and HMBC experiments. The oligosaccharide structures indicate that the cell wall glucanosyl transferase cleaves two glucosyl units from the reducing end of the initial linear beta(1-->3) penta-oligosaccharide and subsequently transfers the remainder to another oligosaccharide at the nonreducing end via a beta(1-->6) linkage. These results indicate that the combined action of cell wall glucanase and glucanosyl transferase activities could not only introduce intrachain beta(1-->6) linkages within a single glucan strand, but also result in cross-linking of two initially separate glucan strands with concurrent introduction of intrachain beta(1-->6) linkages. Since isolated fungal membranes only synthesize linear beta(1-->3) glucan strands, wall-associated enzymes probably participate in the assembly of the final wall glucan structure during cell growth and division.
通过结合使用HCCH-COSY、HCCH-TOCSY和HMBC实验，对由白色念珠菌酵母细胞壁葡聚糖基转移酶酶促制备的均匀13C标记的β-葡聚糖八糖和十一糖的结构进行了表征。寡糖结构表明，细胞壁葡聚糖基转移酶从初始线性β(1→3)五糖的还原端切割两个葡萄糖基单元，随后通过β(1→6)键将其余部分转移到非还原端的另一个寡糖上。这些结果表明，细胞壁葡聚糖酶和葡聚糖基转移酶活性的联合作用不仅可以在单个葡聚糖链内引入链内β(1→6)键，还可以导致两条最初分开的葡聚糖链交联，同时引入链内β(1→6)键。由于分离的真菌膜仅合成线性β(1→3)葡聚糖链，壁相关酶可能在细胞生长和分裂过程中参与最终壁葡聚糖结构的组装。
