172. Lee, Jong H. and R. M. Brown, Jr. 1997. A comparative structural characterization of two cellobiohydrolases from Trichoderma reesei: A high resolution electron microscopy study.  J. Biotechnology 57: 127-136
 172. Abstract

The molecular structure of two homogeneously purified cellobiohydrolases from Trichoderma reesei has been studied employing high resolution transmission electron microscopy (TEM) and digital image processing. By combining low dose TEM, a 3% (w/v) solution of methylamine tungstate as the negative staining agent, and digital image processing, it has been possible to unambiguously view molecular architecture of cellobiohydrolases from Trichoderma reesei. Cellobiohydrolase I(CBH I) and Cellobiohydrolase II (CBH II) have ellipsoidal heads and long, extended helical tails. CBH I has a head with an average diameter of 4.5 - 0.5 nm. The average length of CBH I is 15.1+- 1.3 nm. CBH II has a head with an average diameter of 4.4 - 0.3 nm. Average length of CBH I is 13.4+- 2.6 nm. Overall, the structure of the digitally enhanced TEM images of these two glycosyl hydrolases correlated well with the reported small angle X-ray scattering analysis (SAXS) models, thereby establishing the reliability of high resolution TEM studies in a novel way. The linker regions (LRs) of two CBHs have been visualized. The LR of both enzymes are probably helical in nature, suggesting an extended peptide sequence that lacks secondary structure due to the lack of amino acid/amino acid interactions in this region. A possible structural and functional role of O-glycosylation on these linker regions is given by combining the TEM observations with known biochemical data

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