CALCULATION OF MOLECULAR WEIGHTS AND KJELDAHL NITROGEN-TO-PROTEIN CONVERSION FACTORS FOR MYOFIBRILLAR PROTEINS FROM AMINO ACID SEQUENCES

The objectives of this research were to calculate the molecular weights and Kjeldahl conversion factors for the major myofibrillar proteins from knowledge of their primary structures. Kjeldahl nitrogen-to-protein conversion factors for the myofibrillar proteins myosin, actin, and tropomyosin were calculated from amino acid sequences found in the literature. The molarity of pure protein solutions can be determined without the use of a primary standard with the Kjeldahl nitrogen determination method and use of calculated Kjeldahl nitrogen-to-protein conversion factors. The molecular weights of bovine myosin (519,725), actin (41,549), alpha-tropomyosin (32,680), and beta-tropomyosin (32,811) were calculated. The nitrogen-to-protein conversion factors for these proteins were calculated to be respectively 6.05, 6.29, 6.24, and 6.25. The molecular weights of myosin light chains L1, L2, L3, and L4 and the myosin heavy chain were calculated and their respective nitrogen-to-protein conversion factors were: 6.18, 6.34, 6.34, 6.32, and 6.01.