THERMAL AGGREGATION OF MIXED FISH MYOSINS

Cod and herring myosin solutions were mixed in five different ratios and heated to between 30 and 55 degrees C for 30 min. Extent of aggregation of the myosin solutions increased significantly (p < 0.05) with higher cod/herring myosin ratios at temperatures less than or equal to 40 degrees C. However, there was no significant difference (p < 0.05) in the extent of aggregation among the mixed and herring myosin samples above 45 degrees C. Two transition temperatures (T-m) were observed at 34 and 43 degrees C in cod myosin when the protein solution was heated from 25 to 56 degrees C at 1 degrees C/min, whereas herring myosin exhibited one T-m at 49 degrees C and the mixed myosin samples displayed an extra T-m at 39 degrees C which was absent in the pure cod or herring myosin samples. When a preheated herring myosin solution was mixed with unheated cod myosin in a ratio of one to one and the mixture was reheated at the same temperature, the extent of aggregation was significantly higher (p < 0.05) than the control heated at temperatures between 40 and 50 degrees C. Electrophoretic analysis revealed that more large myosin polymers were formed in the cod/preheated herring myosin samples than in the controls or in herring myosin alone, suggesting that preheated herring myosin and/or myosin aggregates interact with cod myosin, leading to the formation of larger mixed protein aggregates at temperatures between 40 and 50 degrees C.