Inactivation of Yeast Hexokinase B by Triethyltin Bromide and Reactivation by Dithiothreitol and Glucose

Document Type

Article

Publication Date

9-27-1983

Publisher

American Chemical Society

Source Publication

Biochemistry

Source ISSN

0006-2960

Original Item ID

DOI: 10.1021/bi00289a005

Abstract

Binding of triethyltin bromide to yeast hexokinase B results in a rapid change in the reactivity of the sulfhydryl groups of the molecule. The change was characterized by an increased rate as well as extent of reaction of the -SH groups, and it preceded the onset of inhibition of the enzyme. Rapid gel filtration of the enzyme-triethyltin complex reversed this change in sulfhydryl reactivity, and when the eluted enzyme was subjected to short incubation periods, the slow inhibition that occurs with the unfiltered enzyme-triethytin complex was no longer manifested. With prolonged incubation, however, the gel-filtered sample demonstrated increased rate of loss of enzyme activity, indicating that the gel filtration step did not completely reverse the effects of triethyltin on the enzyme. Active enzyme was recovered, following the inactivation of yeast hexokinase with triethyltin, by incubation of the inactivated enzyme with a large excess of glucose and dithiothreitol. Near total recovery of enzyme activity with reversion to native enzyme conformation was achieved following incubation at 35 ℃ of the enzyme with glucose and dithiothreitol each 0.1 M. The possible involvement of either cysteine or histidine in the binding of triethyltin to the enzyme was probed, and it was concluded that neither of these amino acids are donor ligands for tin.

Comments

Biochemistry, Vol. 22, No. 20 (September 27, 1983): 4642-4646. DOI.

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