INVITRO NONENZYMATIC GLYCOSYLATION OF MYOFIBRILLAR PROTEINS

1. Glycation is non-enzymatic modification of proteins by sugars in which not only structural but also biological properties of proteins are altered. 2. Our in vitro experiments show that incubation of myofibrillar 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 dependence of ATPase activity of myofibrils incubated with ribose on the amount of 2-mercaptoethanol present suggests that also modification of SH groups is involved in enzyme inactivation. 5. Electrophoretic studies revealed that heavy chains of myosin, actin, and tropomyosins are proteins which are mainly glycated in vitro.