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 and gastrocnemius) were investigated using differential scanning calorimetry and turbidity (OD350nm) measurements. Peptide mapping showed that 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 muscle myosins required T > 45 degrees C for aggregation. The rates of aggregation were rapid at lower temperatures and then decreased as temperature increased. The red muscle myosins were more similar in peptide maps in comparison to the white muscle myosin; however, there were unique denaturation and aggregation properties for each type of myosin.