From the part soluble at pH 6.4 of tryptic hydrolyzate of β-chain in Macaca mulatta monkey hemoglobin, the so-called `soluble tryptic peptides\u27 were isolated and purified by column and paper chromatography. Four of these peptides, which were called βT9, βT13, βT14, and βT15, were hydrolyzed with pepsin and isolated by column and paper chromatography. Then, amino acid compositions of the four peptides were analyzed and sequences were determined by the DNP and PTC methods. The results were compared respectively with the amino acid sequences of the corresponding peptides in human hemoglobin. Differences between the two hemoglobins were found in βT9 and βT13, namely, human hemoglobin has alanine at the tenth position from the N-terminus of βT9, whereas macaca mulatta monkey hemoglobin has asparagine. Similarly, the former has proline at the fifth position from the N-terminus of βT13, whereas the latter, glutamine. The sequence of the remaining forty amino acid residues were all the same with each other
