Purification of transglutaminase and its effects on myosin heavy chain and actin of spent hens.

The purpose of this study was to purify pig plasma transglutaminase (TGase) and examine its effects on the myosin heavy chain and actin of the breast muscles from spent hens at different temperatures. TGase (0.3 units/mg) was added to myofibrillar proteins solution (0.5 ml) at 4°C for 0, 4, 8, 12, 24 and 48 h; at 25°C for 0, 1, 2, 4, 8, 12, 24 and 48 h; at 37°C for 0, 5, 10, 30 and 60 min. The results of sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) showed that plasma TGase was composed of units of molecular weights approximately 75,000 and 80,000. TGase added to the myofibrillar proteins solution indicated that the concentration of the myosin heavy chain and actin decreased when incubated at 4°C for 48 h and when incubated at 25°C for 2 h. Moreover, the relative intensity determined by scanning densitometry of the SDS-PAGE gel indicated that the myosin heavy chain and actin concentration decreased to 45 and 64%, respectively. In addition, the relative intensity of the myosin heavy chain and actin declined to 7 and 63%, respectively, when incubated at 37°C for 5 min. The relative intensity of both the myosin heavy chain and actin decreased with time when incubated at 25 and 37°C.