Functional Properties of Human Hemoglobin and Isolated Hemoglobin Chains Treated with Organic Mercurials

The functional properties of human hemoglobin and of isolated α‐ and β‐chains with free SH groups blocked by 2‐chloromercuri‐4‐nitrophenol, 4‐chloromercuri‐2‐nitrophenol and p‐chloromercuribenzoate have been determined. The oxygen affinity of all the hemoglobin derivatives is slightly higher than that of the untreated protein; the shape of the oxygen equilibrium curve is pH dependent (except for p‐chloromercuribenzoate reacted hemoglobin). The alkaline Bohr effect is similar to that of normal hemoglobin, but in the acid range it appears to be modified to a different extent in the various cases. Thus the properties of the modified hemoglobins appear to depend on the details of structure of the organic mercurial reacted with the β93‐SH group. The results with isolated β‐chains show that the presence of the organic mercurials on F9(93), but not on G14(112) is associated with a decrease in oxygen affinity and a large increase in the oxygen dissociation velocity constant.