Characterization of a β-glucosidase produced by a high-specific growth-rate mutant of Cellulomonas flavigena

Gaspar A. Barrera-Islas, Ana C. Ramos-Valdivia, Luis M. Salgado, Teresa Ponce-Noyola

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Abstract

The mutant strain PN-120 of Cellulomonas flavigena produces a β-glucosidase that is 10-fold more active than the corresponding enzyme isolated from the parental strain. These enzymes were partially purified through Q Sepharose and Bio-Gel filtration. A single protein band was detected on polyacrylamide-gel electrophoresis/zymogram using 4-methylumbelliferyl-β-D- glucoside. On sodium dodecyl sulfate-PAGE, the enzyme displayed three protein bands, suggesting that in C. flavigena the enzyme is oligomeric with a molecular mass of 210 kDa. On purification, the specific activity of β-glucosidase isolated from PN-120 was increased 16-fold and showed three times more affinity for cellobiose than the enzyme of the parental strain; nevertheless, the optimum pH and temperature were similar for both enzymes. The kinetic parameters suggested that the increase in the activity of the enzyme, from the mutant strain, was caused by a mutation that affects the catalytic site of the enzyme. The partial amino-acid sequence of the isolated enzyme confirmed that it is a β-glucosidase because of its homology with other β-glucosidases produced by cellulolytic bacteria and fungi. © 2007 Springer Science+Business Media, LLC.
Original languageAmerican English
Pages (from-to)266-270
Number of pages5
JournalCurrent Microbiology
DOIs
StatePublished - 1 Apr 2007
Externally publishedYes

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