The absorption spectra and extinction coefficients of myoglobin.

In a study of the quantitative variations of myoglobin in muscles, the need arose for reliable absorption spectra and extinction coefficients of derivatives of both myoglobin and hemoglobin in the visible range. Sufficient data on hemoglobin are available in the literature, but those for myoglobin (1, 2) are conflicting and suggest the need for further study. Therefore, it seemed advisable to publish the results of this study of the absorption spectra of myoglobin and its derivatives in the visible range. Since the maxima and minima of derivatives of myoglobin in the visible range are 2 to 10 rnp nearer the long wave-lengths than those of hemoglobin (l-4), it was thought of interest to study the absorption curves of myoglobin in the near i&a-red and compare them with the curves of hemoglobin obtained by Horecker (5). Consequently, this paper presents absorption curves and molar extinction coefficients of horse heart myoglobin and several of its derivatives at wave-lengths from 1000 to 450 rnp. Studies were made of reduced (Mb) and oxidized, or met (MMb), forms and the derivatives, oxymyoglobin (MbOz), carbonylmyoglobin (MbCO), and metcyanmyoglobin (MMbCN). Metmyoglobin (MMb) was studied at several pH values.