Caracterização da maciez da carne por análises proteômicas e moleculares
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2016-03-24
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Universidade Federal de Goiás
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The protein profile of hornless Nellore cattle from a segregating population for meat tenderness of
extremes shear force, low extreme group (M) and extreme high (D) group, showed differentially
expressed proteins. They had greater relative abundance of proteins of the glycolytic process in
group M and proteins of the oxidative metabolism evidenced more expressed in group D, fact that
probably is correlated to the final tenderness of the meat. Only identified in group D, the
cytochrome c protein indicates induction of the apoptotic process in this group of animals.
Structural proteins were identified in group M, indicating a possible greater proteolysis. Calpastatin
was only identified in group D, this protein is highly related to the final meat tenderness because it
is a natural inhibitor of the calpain. Separation of calpastatin by ion exchange column
chromatography of two different muscles described two peaks of calpain inhibitory activity: peak 1
(CAST1) and peak 2 (CAST2). CAST 1 activity increased during the post-mortem period in
Triceps brachii and showed no difference between days in Longissimus dorsi and on the other
hand, total activity of calpastatin and CAST 2 decreased during post-mortem aging. The 115 kDa
band of calpastatin decreased its intensity during post-mortem aging in both muscles with more
than 70% of the change occurring on the first day. The mitochondrial ATP synthase beta subunit
proteins increased and Succinyl CoA ligase decreased after aging and Adenylate kinase isoenzyme
decreased on day 7. Calpastatin peaks had weak phosphorylated bands and had different IP and
MW patches than 2D-SDS -PAGE. During the purification process of the calpastatin peaks the
activity per mg of protein increased but lost half of the total activity presented during the first
purification step. For peak 2 of calpastatin the specific activity increased 139.8 times and at the end
of this process 36% of the total activity remained. Purified calpastatin was identified on the
second-size gel having a molecular weight similar to the western blot. Spots from calpastatin peak
1 and two from calpastatin peak 2 were identified as peptides belonging to the calpastatin
molecule. Sequence of peptides identified in Spot from purified peak 1 as part of the inhibitory
domain III and IV and of the C-terminus and from the purified peak 2 a sequence of peptides
identified as part of the inhibitory domain I, II and III. These results lead us to believe that both
peaks, in this case, are degradation products of the intact molecule, and probably the small peptides
are broken down during the process. The results of the present study show that purification of
distinct forms of active calpastatin is possible, however, the intact form of calpastatin was not
present in this purification. The presence of peptides was not conclusive to determine the origin
and composition of each active peak.
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OLIVEIRA, L. G. Caracterização da maciez da carne por análises proteômicas e moleculares. 2016. 115 f. Tese (Doutorado em Ciência Animal) - Universidade Federal de Goiás, Goiânia, 2016.