Notes on Myoglobin Preparation and Iron Content

Since the first description by Theorell (11) of a process of isolating and purifying myoglobin from horse heart by crystallization, several workers have succeeded in preparing myoglobin by Theorell’s procedure. Roche and Vieil (8) and Rossi and Aragona (9) have described methods less arduous than Theorell’s. Their methods, however, sacrifice yield to gain simplicity. We have developed a modification of Theorell’s procedure for preparing horse heart myoglobin in which the more than twenty steps described by him are reduced to about ten with no sacrifice of yield. During the work, difficulty was experienced in attaining purity of the preparations based on the value for the iron content, 0.345 per cent, reported by Theorell (11) and others. It became apparent t’hat the value 0.345 per cent iron is greater than the value computed from the ratio in myoglobin of iron content (1 atom per molecule) and the molecular weight. The results of analyses of our preparations indicate that the value computed from the molecular weight derived from sedimentation and diffusion constants can be used as a criterion of purity of myoglobin.