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Published February 12, 1957 | public
Journal Article

The N-Terminal Amino Acid Residues of Normal Adult Human Hemoglobin: A Quantitative Study of Certain Aspects of Sanger's DNP-Method

Abstract

A quantitative redetermination of the N-terminal valyl residues of normal adult human hemoglobin by the DNP-method of Sanger has led us to question the validity of results previously reported. Our experimental results indicate that there are 3,6 N-terminal valyl residues per molecule, based on a molecular weight of 66,700 for human hemoglobin. The essential difference between this value and those of other investigators lies in a correction factor for operational, chromatographic and hydrolytic losses (13%) which is appreciably lower than any previously reported value. This low value is justified by a detailed study of losses with DNP-valine and two peptides, DNP-Val-gly and DNP-Val-leu, the latter an important hydrolytic product of human hemoglobin itself. On the basis of these results an integral value for the number of end groups in human hemoglobin can be achieved only by revising the molecular weight, If, on the other hand, the number of N-terminal valyl residues in human hemoglobin is non-integral, it may well indicate that normal adult human hemoglobin contains more than one kind of molecule.

Additional Information

© 1957 American Chemical Society. Received August 3, 1956. We wish to express our appreciation to Dr. M. Murayama for supplying several samples of hemoglobin and for carrying out the electrophoretic tests for homogeneity, and to Drs. R. Srinivasan and J. Vinograd for making available their unpublished work on the molecular weight of human hemoglobin. This investigation was supported in part by a research grant (RG-4276) from the National Institutes of Health, Public Health Service.

Additional details

Created:
August 19, 2023
Modified:
October 18, 2023