Purification and Characterization of a Major Secretory Cellobiase, Cba2, From Cellulomonas Biazotea

Protein Expr Purif. 2001 Oct;23(1):159-66. doi: 10.1006/prep.2001.1486.

Abstract

A novel cellobiase (Cba2) was purified from the culture supernatant of Cellulomonas biazotea and characterized. Cba2 appeared to be a major secretory cellobiase in C. biazotea as its enzymatic activity was estimated to represent over 40% of the total extracellular beta-glucosidase activity. The enzyme was purified over 260-fold subsequent to ammonium sulfate precipitation, gel-filtration chromatography, anion-exchange chromatography, and reversed-phase high-performance liquid chromatography. Cba2 was shown by SDS-PAGE to have a large molecular mass of 109 kDa, which makes it one of the largest secretory cellobiases characterized. Its homogeneity was confirmed by N-terminal amino acid sequencing. The K(m) and V(max) values were 0.025 mM and 0.0048 mM min(-1), respectively, for the Cba2 hydrolysis of p-nitrophenyl-beta-d-glucopyranoside, and 0.73 mM and 0.00033 mM min(-1), respectively, for the hydrolysis of cellobiose (at 37 degrees C and pH 7.0). The purified enzyme has a pH optimum of 4.8 and the optimum temperature for activity is 70 degrees C. In view of the secretory nature of Cba2 and the fact that it is a major component of secretory cellobiases of C. biazotea, it is potentially important in the enzymatic degradation of cellulose, and its availability as a recombinant protein may facilitate the studies of its biotechnological applications.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actinomycetales / enzymology*
  • Chromatography
  • Chromatography, High Pressure Liquid
  • Electrophoresis, Polyacrylamide Gel
  • Hydrogen-Ion Concentration
  • Kinetics
  • Molecular Weight
  • Sequence Analysis, Protein
  • Temperature
  • beta-Glucosidase / isolation & purification*
  • beta-Glucosidase / metabolism

Substances

  • beta-Glucosidase