DENATURATION AND AGGREGATION OF CHICKEN MYOSIN ISOFORMS

Heat-induced denaturation and aggregation of chicken myosins isolated from one white muscle (pectoralis) and two red muscles (iliotibialis a nd gastrocnemius) were investigated using differential scanning calori metry and turbidity (OD350nm) measurements. Peptide mapping showed tha t the three myosins had different heavy chain isoforms. Pectoralis and iliotibialis myosins had higher calorimetric enthalpies and a higher denaturation onset temperature than gastrocnemius myosin. Aggregation occurred for the pectoralis myosin at 45 degrees C, while the red musc le myosins required T > 45 degrees C for aggregation. The rates of agg regation were rapid at lower temperatures and then decreased as temper ature increased. The red muscle myosins were more similar in peptide m aps in comparison to the white muscle myosin; however, there were uniq ue denaturation and aggregation properties for each type of myosin.