Allosteric serine hydroxymethyltransferase from monkey liver: Correlation of conformational changes caused by denaturants with the alterations in catalytic activity.
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Date
1981-06
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Abstract
The far-ultraviolet region circular dichroic spectrumof serine hydroxymethyltransferase
from monkey liver showed that the protein is in an α-helical conformation. The
near ultraviolet circular dichoric spectrum revealed two negative bands originating from the
tertiary conformational environment of the aromatic amino acid residues. Addition of urea or
guanidinium chloride perturbed the characteristic fluorescence and far ultraviolet circular
dichroic spectrum of the enzyme. The decrease in (θ)222 and enzyme activity followed identical
patterns with increasing concentrations of urea, whereas with guanidinium chloride, the loss of
enzyme activity preceded the loss of secondary structure. 2-Chloroethanol, trifluoroethanol
and sodium dodecyl sulphate enhanced the mean residue ellipticity values. In addition,
sodium dodecyl sulphate also caused a perturbation of the fluorescence emission spectrum of
the enzyme. Extremes of pH decreased the – (θ)222 value. Plots of –(θ)222and enzyme activity
as a function of pH showed maximal values at pH 7.4-7.5. These results suggested the
prevalence of "conformational flexibility" in the structure of serine hydroxymethyltransferase.
Description
Keywords
Serine hydroxymethyltransferase, conformational changes, denaturants, fluorescence, circular dichroism, structure-activity relationship
Citation
Ramesh Kashi S, Anantanarayanan V S, Rao N Appaji. Allosteric serine hydroxymethyltransferase from monkey liver: Correlation of conformational changes caused by denaturants with the alterations in catalytic activity. Journal of Biosciences. 1981 Jun; 3(2): 167-178.