THERMAL-DENATURATION OF MUSCLE PROTEINS FROM MALE AND FEMALE SQUID (ILLEX-ARGENTINUS) AT DIFFERENT SEXUAL-MATURATION STAGES - A DIFFERENTIAL SCANNING CALORIMETRIC STUDY

The influence of both sex and sexual maturation stage of specimens on the thermal behavior of muscle proteins was investigated. Differential scanning calorimetry (DSC) thermograms of whole muscle of female squi ds showed four endothermic transitions [peak temperature maximum (T-ma x), 45.9, 56.8, 67.2, and 79.2 degrees C]. The DSC thermograms of whol e muscle of male squids showed three transitions (T-max, 47.9, 56.8, a nd 79.2 degrees C). The T-max of 67.2 degrees C, present only in femal e squid muscle, was related to sarcoplasmic proteins. Myosin and param yosin contributed to the first transition, connective tissue to the se cond transition, and actin to the last transition. No major difference s were observed in T-max values that were related to the sex and sexua l maturation stage of specimens. The lowest denaturation enthalpy (Del ta H) was found in muscle from immature females. Independently of the sex and the sexual maturation stage of specimens, no major changes wer e observed in either T-max or Delta H values during frozen storage of squids.