Studies on DNP-Protamines by Means of the Absorption Spectra

Abstract

Abstract 1) DNP-Derivatives of amino compounds gave the characteristic spectral absorption curves, according to the states of the amino groups combined with the DNP-group. It was found, that 2,4-dinitroaniline as a primary amine, DNP-monoamino acids in the case of secondary amine and DNP-proline in that of tertiary amine gave respectively the absorption spectra with different absorption maxima and absorption coefficients (cf. Table I and Fig. 1). 2) The absorption curve of DNP-clupeine was of the similar shape to DNP-derivatives in the states of secondary amines, while that of DNP-salmine in those of tertiary amines. From this fact the difference between the N-terminal residues of clupeine and salmine molecules was evidently recognized, that of the former being monoamino acid while that of the latter proline. 3) By comparing the absorption of DNP-protamine with the molecular absorption coefficient of the corresponding DNP-amino acid which occupies the N-terminal residue in the molecule, the molecular weights of DNP-derivatives of clupeine and salmine were estimated. Both clupeine and salmine were shown to have the molecular weights of the same order, 6,000–7,000.