Open Accessβ‐Glucosidase activity from the thermophilic fungus Scytalidium thermophilum is stimulated by glucose and xylose
Author(s) -
Zanoelo Fabiana Fonseca,
Polizeli Maria de Lourdes Teixeira de Moraes,
Terenzi Héctor Francisco,
Jorge João Atílio
Publication year - 2004
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1016/j.femsle.2004.09.021
Subject(s) - cellobiose , xylose , enzyme , hydrolysis , chemistry , thermophile , biochemistry , enzyme assay , stereochemistry , cellulase , fermentation
An inducible mycelial β‐glucosidase from Scytalidum thermophilum was characterized. The enzyme exhibited a p I of 6.5, a carbohydrate content of 15%, and an apparent molecular mass of about 40 kDa. Optima of temperature and pH were 60 °C and 6.5, respectively. The enzyme was stable up to 1 h at 50 °C and exhibited a half‐life of 20 min at 55 °C. The enzyme hydrolyzed p ‐nitrophenyl‐β‐ d ‐glucopyranoside, p ‐nitrophenyl‐β‐ d ‐xylopyranoside, o ‐nitrophenyl‐β‐ d ‐galactopyranoside, p ‐nitrophenyl‐α‐arabinopyranoside, cellobiose, laminaribiose and lactose. Kinetic studies indicated that the same enzyme hydrolyzed these substrates. β‐Glucosidase was activated by glucose or xylose at concentration varying from 50 to 200 mM. The apparent affinity constants ( K 0.5 ) for glucose and xylose were 36.69 and 43.24 mM, respectively. The stimulatory effect of glucose and xylose on the S. thermophilum β‐glucosidase is a novel characteristic which distinguish this enzyme from all other β‐glucosidases so far described.