SULFHYDRYL AND DISULFIDE GROUPS OF PROTEINS : III. SULFHYDRYL GROUPS OF NATIVE PROTEINS-HEMOGLOBIN AND THE PROTEINS OF THE CRYSTALLINE LENS.

Hemoglobin and the proteins of the crystalline lens contain active SH groups while in the native state, the number of active groups increasing as the pH rises. All the SH groups of denatured globin and of the denatured lens proteins are active at a pH so low that practically none of the SH groups of native hemoglobin and of native lens protein are active. The effect of denaturation on the SH groups of a protein is to extend towards the acid side the pH range of their activity. It is possible to oxidize the iron-porphyrin and the SH groups of hemoglobin independently of each other.