Organotin-Protein Interactions. Binding of Triethyltin Bromide to Cat Haemoglobin

Document Type

Article

Publication Date

1-1986

Publisher

Portland Press Limited

Source Publication

Biochemical Journal

Source ISSN

0264-6021

Original Item ID

DOI: 10.1042/bj2330471

Abstract

Triethyltin binds to native cat and rat haemoglobin but not to their denatured forms or to other animal haemoglobins. Two molecules of the organotin bind to one molecule of R-state cat haemoglobin with affinity constants of about 1 × 105 M-1. Little or no triethyltin is bound to the deoxygenated (T-state) protein. Binding appears to be dependent upon the existence of a specific three-dimensional configuration of cysteine and histidine residues. The properties of the triethyltin-cat haemoglobin complex are consistent with those of a haemoglobin conformer whose allosteric equilibrium is displaced toward the R-state. Its oxygen affinity and rate of oxidation by nitrite is increased, and the rate of reduction of the methaemoglobin derivative by ascorbate is decreased. These effects of triethyltin are opposite and antagonistic to the effects of inositol hexaphosphate. They are exerted on the alpha- as well as beta-haem groups, even though triethyltin is bound at sites on alpha-globin far removed from the haem groups.

Comments

Biochemical Journal. Vol. 233, No. 2 (January 1986): 471-477. DOI.

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