Elucidation of Factors Responsible to Raise Dependency of Mg-ATPase Activity of Myofibrils on KCI Concentrations during Meat Conditioning.

Accession number;00A0535462
Title;Elucidation of Factors Responsible to Raise Dependency of Mg-ATPase Activity of Myofibrils on KCI Concentrations during Meat Conditioning.
Author; MATSUISHI M (Nippon Veterinary And Animal Sci. Univ., Musashino-shi, Jpn) OKITANI A (Nippon Veterinary And Animal Sci. Univ., Musashino-shi, Jpn)
Journal Title;Anim Sci J
Journal Code:F0902A
ISSN:1344-3941
VOL.71;NO.3;PAGE.280-291(2000)
Figure&Table&Reference;FIG.11, REF.16
Pub. Country;Japan
Language;English
Abstract;In order to clarify factors inducing the changes in the Mg-ATPase activity of myofibrils during meat conditioning, we treated myofibrils in vitro with various muscle proteinases and Ca2+. Ca2+ or proteasome did not change the Mg-ATPase activity at 25.DEG.C. and pH 5.5 or 7.0. m-Calpain enhanced the dependency of the Mg-ATPase activity of myofibrils on KCI concentrations (DAAK) in the range of O to 0.05 M KCI at 25.DEG.C. and pH 7.2 as similarly as observed during meat conditioning, but did not at pH 5.5. Therefore, m-calpain was assumed to contribute to the increase in DAAK in the early stage of meat conditioning, i.e., before the pH of muscle declined to the ultimate pH. Crude cathepsins raised DAAK in the range of 0 to 0.1 M KCI at 25.DEG.C. and both pH 5.5 and 7.0. As a result of the chromatographic separation, cathepsins D and L were shown to enhance DAAK remarkably. Although cathepsins B and H alone raised DAAK only a little, their action was enhanced by the coexistence of cathepsin L. During meat conditioning cathepsins D and L are thus considered to contribute to the increase in DAAK involving a synergistic action of cathepsins B and H. However, all these proteinases investigated here did not cause so much remarkable increase in the maximum value of the Mg-ATPase activity of myofibrils occurring at low KCI concentrations as observed during meat conditioning, suggesting the existence of other unknown factors inducing such changes. (author abst.)