Linked Life Data

19329480

Source:http://linkedlifedata.com/resource/pubmed/id/19329480

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
6
pubmed:dateCreated
2009-5-15
pubmed:abstractText
Muscle shortening and postmortem proteolysis both influence beef tenderness, but their interacting effects on tenderness are relatively unknown. Inherent myofibril structure and the extent of overlap between myosin and actin filaments are hypothesized to affect the availability of substrates for degradation by calpains. The objective of this study was to determine the influence of sarcomere length on the extent of calpain-induced proteolysis of bovine myofibrils in vitro. Bovine semitendinosus muscles were excised within 20 min postmortem and dissected into strips, which were stretched and attached to applicator sticks or allowed slack to generate samples with different sarcomere lengths upon rigor completion. Samples were allowed to undergo rigor in a neutral pH buffer containing a protease inhibitor. Myofibrils were isolated and incubated at room temperature with excess exogenous mu-calpain at a ratio of 1:800 (wt/wt; enzyme:myofibrillar protein) at pH 6.8 for 0, 2, 60, 1,440, or 2,880 min. Purified troponin was subjected to the same digestion conditions. Proteolysis of troponin T (TnT) was monitored using SDS-PAGE and Western blotting. Sarcomere length was greater (P < 0.0001) in stretched versus shortened samples (2.99 microm +/- 0.03 vs. 2.12 +/- 0.03 microm, respectively, means +/- SE). Western blots for both stretched and shortened samples exhibited bands corresponding to intact TnT and TnT fragments. The abundance of intact TnT decreased (P < 0.0001) with incubation time across both treatments. At 1,440 and 2,880 min, less (P < 0.05) intact TnT was detected in samples with long sarcomeres. These data indicate proteolysis of TnT occurs to a greater extent in samples with longer sarcomeres, possibly due to easier access of proteases to their targeted substrates. Degradation patterns of TnT were qualitatively similar between myofibrils and purified troponin after incubation with mu-calpain. Therefore, it is unlikely that the mechanism by which proteolysis is limited in short sarcomeres involves an actomyosin-mediated interference of TnT.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
1525-3163
pubmed:author
pubmed:issnType
Electronic
pubmed:volume
87
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
2096-103
pubmed:meshHeading
pubmed:year
2009
pubmed:articleTitle
Sarcomere length influences mu-calpain-mediated proteolysis of bovine myofibrils.
pubmed:affiliation
Department of Animal Sciences, Purdue University, West Lafayette, IN 47907, USA.
pubmed:publicationType
Journal Article