The Effect of Sulfhydryl Reagents on the Binding of Human Hemoglobin to Haptoglobin

摘要

Human hemoglobin was treated with the following sulfhydryl reagents: iodoacetamine, p-mercuribenzoate, cystine, cystamine, N-ethylmaleimide and bis(N-maleimidomethyl) ether (BME). Only BME hemoglobin showed impaired binding to serum haptoglobin. An excess of free BME hemoglobin was required to saturate the haptoglobin of normal serum. Competition studies indicated that BME hemoglobin bound haptoglobin about one-fourth as readily as normal hemoglobin. This finding was independent of haptoglobin phenotype. BME hemoglobin could be readily displaced from haptoglobin by an excess of 'normal' hemoglobin. Impaired binding to haptoglobin is yet another property which BME hemoglobin shares with deoxyhemoglobin. Possible mechanisms for this phenomenon are discussed. (Author)