Ultraviolet Absorption Spectra of ?-irradiated Cytochrome-C

Difference spectra of γ-irradiated versus unirradiated solutions of cytochrome-C, of the amino acids constituting cytochrome-C and of aromatic amino acids have been investigated under various conditions. In the neutral solution of cytochrome-C, a broad increase in absorbance over the range from 2350 to 3420 A with maxima at 2420, 2870 and 2970 A, and a minimum at 2900 A was observed. The over-all pattern in the observed difference spectrum of irradiated vs. unirradiated neutral solution of cytochrome-C may be explained in terms of two separate functions: one arises from the conformational change of cytochrome-C and the other comes out of the formation of new chromophore absorbing light around 2970 A, on which the superimposition of the former is most likely to occur.

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