Binding of 4-methylumbelliferyl-beta-D-ribopyranoside to beta-D-xylosidase from Bacillus pumilus.

Paper

Binding of 4-methylumbelliferyl-beta-D-ribopyranoside to beta-D-xylosidase from Bacillus pumilus.

Published 1978 · M. Claeyssens, C. de Bruyne

Biochimica et biophysica acta

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Abstract

The determination of the binding parameters of 4-methylumbelliferyl-beta-D-ribopyranoside, a fluorescent ligand of beta-D-xylosidase (exo-1,4-beta-xylosidase, EC 3.2.1.37) from Bacillus pumilus, is described. A single binding site per polypeptide chain (60 000 daltons) was found and the homogeneity of the binding sites in the dimeric or tetrameric forms of the enzyme were shown. The association constants, as a function of temperature and ionic strength, were obtained from equilibrium binding experiments and compared to the kinetically determined inhibition constants. The apparent discrepancies are attributed to a temperature, ionic strength and concentration dependent shift in the dimer-tetramer equilibrium of the enzyme and different affinities of the ligand for both oligomeric forms. Sedimentation velocity experiments seem to corroborate this hypothesis.

In Vitro Study

Study Snapshot

4-methylumbelliferyl-beta-D-ribopyranoside binds to beta-D-xylosidase from Bacillus pumilus with a single binding site per polypeptide chain, and its association constants vary with temperature and ionic strength, indicating

PopulationOlder adults (50-71 years)

Sample size24

MethodsObservational

OutcomesBody Mass Index projections

ResultsSocial networks mitigate obesity in older groups.

Binding of 4-methylumbelliferyl-beta-D-ribopyranoside to beta-D-xylosidase from Bacillus pumilus.

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