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Unidirectional processive action of cellobiohydrolase Cel7A on Valonia cellulose microcrystals
Author(s) -
Imai Tomoya,
Boisset Claire,
Samejima Masahiro,
Igarashi Kiyohiko,
Sugiyama Junji
Publication year - 1998
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(98)00845-x
Subject(s) - chemistry , cellulose , crystallography , single crystal , nanotechnology , stereochemistry , chemical engineering , organic chemistry , materials science , engineering
On the basis of the ‘parallel‐up' structure of the cellulose crystal, a crystallographic approach to study the mode of action of cellobiohydrolase Cel7A on Valonia cellulose microcrystal has been carried out. After incubation with Cel7A, most of the initially smooth and well defined Valonia microcrystals displayed fibrillation. However, as the hydrolysis reaction was rather heterogeneous, some microcrystals remained superficially intact. Close investigation on such crystals revealed polar morphology: one end was narrowed extremely or pointed. Electron microdiffraction analysis of these crystals evidenced that the narrowing of the microcrystals occurs at their reducing end side. This was also confirmed by the visualization of selective reducing end labeling at the pointed ends of microcrystals. These lines of investigation are the first demonstration that the processivity of Cel7A action against insoluble highly crystalline celluloses is unambiguously toward non‐reducing ends from reducing ends.