Study of methyl bromide reactivity with human and mouse hemoglobin

Abstract

A study has been carried out on in-vitro reactivity of human and mouse hemoglobin spectrophotometrically at physiological pH, using different protein to reagent ratios. Hemoglobin side chains were modified with different concentrations of methyl bromide on agro-soil fumigant. To ascertain if the site of alkylation was the reactive sulfhydryl group present at cystein – 93 on the b chain of hemoglobin (b-93 cys), a spectrophotometric measurement using 5,5-dithiobis(2-nitrobenzoic acid) (DTNB) was used to measure the free sulfhydryl groups before and after treatment of hemoglobin with various amounts of methyl bromide. The results show that the methylbromide reacted substantially with both human and mouse hemoglobin at b-93 cys. The decrease in the number of sulfhydryl groups (SH) per hemoglobin molecule on addition of various concentrations of methylbromide ranges from 5.10 to 2.35 + 0.01 and 5.01 to 0.93 + 0.01 for human and mouse hemoglobin, respectively. The results showed a dose-dependent decrease in the number of sulfhydryl group indicating that hemoglobin can serve as a biomarker of human occupational exposure to methy bromide fumigants. Keywords: Hemoglobin, sulfhydryl groups, methylbromide, Cysteine, histidine. (Global Journal of Pure and Applied Sciences: 2002 9(1): 91-100)