INVITRO NONENZYMATIC GLYCOSYLATION OF MYOFIBRILLAR PROTEINS

1. Glycation is non-enzymatic modification of proteins by sugars in wh ich not only structural but also biological properties of proteins are altered. 2. Our in vitro experiments show that incubation of myofibri llar proteins with ribose results in sugar attachment to proteins and at the same time myofibrillar ATPase activity is lowered. 3. DETAPAC, aminoguanidine and 2-mercaptoethanol all partially block myofibrillar protein glycation and ATPase activity is less inactivated. 4. The depe ndence of ATPase activity of myofibrils incubated with ribose on the a mount of 2-mercaptoethanol present suggests that also modification of SH groups is involved in enzyme inactivation. 5. Electrophoretic studi es revealed that heavy chains of myosin, actin, and tropomyosins are p roteins which are mainly glycated in vitro.