Thermal Stability of Myofibrillar Proteins from Smooth and Striated Muscles of Scallop ( Chlamys tehuelchus ):  A Differential Scanning Calorimetric Study

PAREDI, MARIA E.; TOMAS, MABEL C.; AÑON, MARÍA C.; CRUPKIN, MARCOS

JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY

AMER CHEMICAL SOC

Año: 1998 vol. 46 p. 3971 - 3976

0021-8561

Denaturation of proteins from striated and smooth muscles of scallop (Chlamys tehuelchus) was studied with DSC by monitoring maximum temperatures of transitions and denaturation enthalpies. DSC thermograms of both striated and smooth muscles free of connective tissue showed two transitions, (Tmax of 53.2 and 79 °C) and (Tmax of 52.7 and 78 °C), respectively. These results indicate that the different paramyosin content of the muscles did not influence the thermal stability of their proteins. The DSC thermograms of myofibrils and actomyosin were similar to those corresponding to respective whole muscles. Myosin from striated muscles showed a cooperative single peak with Tmax of 48.8 °C. Similar Tmax values were observed in DSC thermograms of myosin from smooth muscle. As pH and ionic strength increased, the thermal stability of whole muscle decreased. Smooth muscles were more affected than striated muscles. The pH increment significantly affected denaturation enthalpies (¢Htotal and ¢Hpeak I) of whole smooth muscles. Denaturation enthalpies (¢Htotal and ¢Hpeak I) significantly decreased (p < 0.05) when ionic strength increased to 0.5 in both type of muscles.