Chemical Characteristics of Annelid, Mollusc and Arthropod Tropomyosins

　Although much is known concerning the comparative amino acid composition of purified proteins in mammals, less is known about lower vertebrates and very little about invertebrates（1, 2）. A major difficulty in comparative studies is the selection of a protein that is present throughout the animal kingdom. All animals possess locomotion or motility, and, except for those which depend exclusively on cilia or flagellae for motion, muscle tissue is the common instrument of movement. Therefore, a purified muscle protein would appear to be suitable for comparative studies.