title: Effects of exogenous protease effectors on beef tenderness development and myofibrillar degradation and solubility.
abstract: The effects of in situ postrigor injection (24 h postmortem) of exogenous aspartic, serine, and cysteine proteinase effectors into cylindrical beef longissimus samples on tenderness and myofibrillar protein degradation and integrity were studied. Injection of phenylmethanesulphonylfluoride (PMSF) and pepstatin did not influence shear force or protein degradation measured 8 d postmortem, confirming that neither serine nor aspartic proteinases affect tenderization. Injection of leupeptin, an epoxysuccinyl peptide (E-64), or N-acetyl-Leu-Leu-norleucinal (calpain inhibitor I) blocked tenderization completely, as observed by higher (P < .05) shear force values. A causal relationship between increased toughness and prevented action of the cysteine proteinases was suggested by a concomitant reduction of myofibrillar protein degradation, generally reflected in higher (P < .05) remaining troponin-T and titin amounts and lower (P < .05) levels of 30-kDa peptide, as evaluated by semiquantitative SDS-PAGE. Moreover, parallel to these changes, amounts of salt-soluble myofibrillar protein and semiquantitative concentrations of individual salt-soluble proteins (SDS-PAGE) were also reduced (P < .05). Injection of Triton-X-100 and Ca2+ increased (P < .05) tenderness, as well as myofibrillar protein degradation and solubility, and free Ca2+, whereas EDTA induced the opposite results, indicating an important role for calpains in tenderization. Because cathepsin B, D, H, and L inhibitors did not affect texture or proteolysis, our results suggest that calpains are the main proteases involved in beef tenderization.
authors.affiliation: Department of Animal Production, University of Gent, Melle, Belgium.
authors.forename: L
authors.initials: L
authors.lastname: Uytterhaegen
authors.forename: E
authors.initials: E
authors.lastname: Claeys
authors.forename: D
authors.initials: D
authors.lastname: Demeyer
mesh_terms: D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology; D002154:Calpain / Q000037:antagonists & inhibitors / Q000378:metabolism; D002403:Cathepsins / Q000037:antagonists & inhibitors; D002417:Cattle; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D003978:Diazomethane / Q000031:analogs & derivatives / Q000494:pharmacology; D004492:Edetic Acid / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D010450:Endopeptidases / Q000378:metabolism*; D006023:Glycoproteins / Q000494:pharmacology; D007930:Leucine / Q000031:analogs & derivatives / Q000494:pharmacology; D007976:Leupeptins / Q000494:pharmacology; D008297:Male; D008460:Meat / Q000592:standards*; D009124:Muscle Proteins / Q000737:chemistry / Q000378:metabolism*; D009132:Muscles / Q000187:drug effects / Q000201:enzymology*; D017830:Octoxynol / Q000494:pharmacology; D010436:Pepstatins / Q000494:pharmacology; D010664:Phenylmethylsulfonyl Fluoride / Q000494:pharmacology; D011180:Postmortem Changes; D012995:Solubility
chemical_list: D015853:Cysteine Proteinase Inhibitors; D006023:Glycoproteins; D007976:Leupeptins; D009124:Muscle Proteins; D010436:Pepstatins; C024918:benzyloxycarbonylphenylalanylalanine diazomethyl ketone; C039304:calpain inhibitors; C014195:Streptomyces pepsin inhibitor; D000001:Calcimycin; D010664:Phenylmethylsulfonyl Fluoride; D003978:Diazomethane; C031947:benzyloxycarbonylphenylalanylphenylalanine diazomethyl ketone; D017830:Octoxynol; D004492:Edetic Acid; D002403:Cathepsins; D010450:Endopeptidases; D002154:Calpain; D007930:Leucine; C032854:leupeptin; C024974:E 64; D002118:Calcium; C031375:pepstatin