Purification and biochemical characterization of glucose–cellobiose-tolerant cellulases from Scytalidium thermophilum
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Two cellulases from Scytalidium thermophilum were purified and characterized, exhibiting tolerance to glucose and cellobiose. Characterization of purified cellulases I and II by mass spectrometry revealed primary structure similarities with an exoglucanase and an endoglucanase, respectively. Molecular masses were 51.2 and 45.6 kDa for cellulases I and II, respectively, as determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Cellulases I and II exhibited isoelectric points of 6.2 and 6.9 and saccharide contents of 11 and 93 %, respectively. Optima of temperature and pH were 60–65 °C and 4.0 for purified cellulase I and 65 °C and 6.5 for purified cellulase II. Both cellulases maintained total CMCase activity after 60 min at 60 °C. Cysteine, Mn2+, dithiotreitol and ß-mercaptoethanol-stimulated cellulases I and II. The tolerance to cellulose hydrolysis products and the high thermal stabilities of Scytalidium cellulases suggest good potential for industrial applications.
KeywordsCellulase Cellobiose Sodium Acetate Buffer CMCase Activity Saccharide Content
This work was supported by a grant from CNPq. J.C.R.S. received a Ph.D. scholarship from FAPESP, and M.L.T.M.P., R.P.M.F., and J.A.J. are research fellows of CNPq. This work was part of the Doctoral thesis of J.C.R.S (Dept. Bioquímica-FMRP-USP).
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