Isolation and divalent-metal activation of a β-xylosidase, RUM630-BX
Autor: | J. Rose Stoller, Kurt Wagschal, Jay D. Braker, Charles C. Lee, Douglas B. Jordan |
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Rok vydání: | 2016 |
Předmět: |
0301 basic medicine
Rumen Cations Divalent Stereochemistry Recombinant Fusion Proteins Molecular Sequence Data Bioengineering Applied Microbiology and Biotechnology Biochemistry Substrate Specificity Recombinant enzyme 03 medical and health sciences Catalytic Domain Escherichia coli Animals Amino Acid Sequence Glycosides Enzyme kinetics Incubation Nitrobenzenes chemistry.chemical_classification Sequence Homology Amino Acid Chemistry Activator (genetics) Substrate (chemistry) Divalent metal Enzyme Activation Xylosidases 030104 developmental biology Enzyme Cattle Metagenomics Sequence Alignment Biotechnology |
Zdroj: | Enzyme and Microbial Technology. 82:158-163 |
ISSN: | 0141-0229 |
DOI: | 10.1016/j.enzmictec.2015.10.001 |
Popis: | The gene encoding RUM630-BX, a β-xylosidase/arabinofuranosidase, was identified from activity-based screening of a cow rumen metagenomic library. The recombinant enzyme is activated as much as 14-fold (kcat) by divalent metals Mg(2+), Mn(2+) and Co(2+) but not by Ca(2+), Ni(2+), and Zn(2+). Activation of RUM630-BX by Mg(2+) (t0.5 144 s) is slowed two-fold by prior incubation with substrate, consistent with the X-ray structure of closely related xylosidase RS223-BX that shows the divalent-metal activator is at the back of the active-site pocket so that bound substrate could block its entrance. The enzyme is considerably more active on natural substrates than artificial substrates, with activity (kcat/Km) of 299 s(-1) mM(-1) on xylotetraose being the highest reported. |
Databáze: | OpenAIRE |
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