Koyama M, Helbert W, Imai T, Sugiyama J, Henrissat B
Wood Research Institute, Kyoto University, Uji Kyoto 611, Japan.
Proc Natl Acad Sci U S A. 1997 Aug 19;94(17):9091-5. doi: 10.1073/pnas.94.17.9091.
The "parallel-up" packing in cellulose Ialpha and Ibeta unit cells was experimentally demonstrated by a combination of direct-staining the reducing ends of cellulose chains and microdiffraction-tilting electron crystallographic analysis. Microdiffraction investigation of nascent bacterial cellulose microfibrils showed that the reducing end of the growing cellulose chains points away from the bacterium, and this provides direct evidence that polymerization by the cellulose synthase takes place at the nonreducing end of the growing cellulose chains. This mechanism is likely to be valid also for a number of processive glycosyltransferases such as chitin synthases, hyaluronan synthases, and proteins involved in the synthesis of nodulation factor backbones.
通过对纤维素链还原端进行直接染色与微衍射倾斜电子晶体学分析相结合的方法，在实验中证实了纤维素Iα和Iβ晶胞中的“平行向上”堆积。对新生细菌纤维素微纤丝的微衍射研究表明，正在生长的纤维素链的还原端指向远离细菌的方向，这为纤维素合酶在正在生长的纤维素链的非还原端进行聚合反应提供了直接证据。这种机制可能对许多持续性糖基转移酶也同样适用，比如几丁质合酶、透明质酸合酶以及参与根瘤因子骨架合成的蛋白质。
