The proposed research is a continuation of previous work on hemoglobins, catalase, and lactoperoxidase. It is proposed to continue the previous extensive investigation of human hemoglobin F in normal and abnormal hematological conditions by means of precise chemical investigation of the gamma chains. The data to be obtained provide a measure of the relative production on the nonallelic structural genes for the human gamma chains. From these data, the genetic status in abnormal hematological conditions can be evaluated to give an insight into the nature of the disease. Information also is gained about linkage of genes for hemoglobin chains and about the factors and mechanisms that control the production of these genes. The results bear upon the general problem of the control of protein synthesis. The amino acid sequences of bovine and human erythrocyte catalases which are about 75% complete will be finished for comparison with bovine erythrocyte catalase. It is proposed to modify catalase by various reagents in order to learn more about structure in relation to function; if specific effects can be produced, the known sequence permits the point(s) of modification to be determined. Lactoperoxidase, which like catalase also decomposes hydrogen peroxide, will be further studied For comparison with catalase; the emphasis will be on the determination of sequence.