Study On Fresh Pork Quality By Differential Proteomics

The quality of fresh pork is a complicated and multipleunit character. Studies on its intrinsic mechanism, evaluation and management are always the hottest research fields of the meat science. So far, such kinds of researches have been generally focused on lean rates and differences in the quality between normal and poor meat. However, methods for effectively evaluating the quality of the fresh pork and its intrinsic mechanism are still not well established as far as we know. Two-dimensional gel electrophoresis (2-DE), mass spectrometry (MS) and bioinformatics are the three critical technologies of proteomics, which provide us with the new thought to study the intrinsic mechanism of fresh pork quality. With the power of proteomics, the intrinsic mechanism of fresh meat quality and the physiological and biochemical basis of genetic regulation were investigated by searching for and identifying the protein markers of meat quality traits. Thus proteomics offers a related foundation for finding quality genes through cDNA, also evaluation and grade mark of meat quality under different conditions.Therefore, this study was conducted to evaluate the quality of fresh pork of two different species (Jinhua pigs termed as JH, and hybrid pigs of Duroc×Landrace×Yorkshire, termed as DLY) at different postmortem time by using technologies of differential proteomics. We have established the pork muscle proteomic methods of 2-DE conditions through comparing and optimizing the relevant technical parameters, as well as the amino contents was detected. The main results of the present study were as follows:1.The 2-DE techniques of fresh pork musle were established with the relative technique parameters including gel selection, loding amount of protein and program of the isoelectric focusing (IEF). It has been found that the pI of the pork muscle protein was 5-8, while their mass was about 10 KDa-200KDa. The optimized method is that the loding amount of protein is 150μg, and the volume is 300μL. With this mothod, the 2-DE profile was of good resolution and good repetition.2.The comparison study was conducted to analyze the degradation of the proteins at different postmortem time, using the JH and DLY pig muscles (stored at room temperature) as materials. The results showed that High mobility group protein, Zinc finger protein and Fructose-bisphosphate aldolase A of DLY pig fresh were degraded in postmortem 6 h. Acin and desmin were degraded in postmortem 24 h. After 48 h, Acin were degraded significantly, and an uncharacterized protein was found. Also results in JH pig showed that heat shock protein, mitochondrial protein, RWD-domain-containing and an uncharacterized protein were found to be degraded in postmortem 6 h. Actin, CGRP type 1 receptor and Intercellular adhesion molecule were degraded at postmortem 24 h. Actin and other two uncharacterized proteins were significantly up-regulated between postmortem 48 h and 72 h.3.The comparison study was conducted to analyze the degradation of the proteins at different postmortem time, using the JH and DLY pig muscles (stored at 2℃) as materials. The results showed that desmin, Defensin-1 and uncharacterized protein of DLY meat were degraded at postmortem 6 h. Troponin T and uncharacterized protein were degraded at postmortem 24 h. After 48 h, Thy-1 membrane glycoprotein, Peroxiredoxin and SOD were degraded. Actin was significantly degraded from postmortem 96 h to 144 h, and a uncharacterized protein was found Also results in JH pig showed that heat shock protein, desmin and an uncharacterized protein were found to be degraded in postmortem 6 h. Troponin T, Aquaporin-11 and Zinc finger protein were degraded in postmortem 24 h. Actin and Peroxiredoxin-4 proteins were significantly up-regulated at postmortem 48 h. Myosin heavy chain, SHC-transforming protein 3 and uncharacterized protein were found to be degraded from postmortem 96 h to 144 h.4.The comparison study was conducted to analyze the differentially expressed proteins between two breeds (JH pig and DLY pig). The results obtained from the samples prepared at 0 h indicated that there were three different proteins(Sarcolumenin; Leucine rich repeat and heat shock protein) between two species of pig. As for the samples at 24 h, three differential proteins(Adenylate kinase; ATP phosphoribosyltransferase and 26S protease regulatory protein) were observed. The differential proteins obtained from the samples prepared at 48 h indicated that there were three different proteins (Zinc fingering protein; (3-enolase and desmin) were significantly up-regulated. According to the postmortem 72 h samples, Pyruvate kinase, NADH-ubiquinone oxidoreductase, Glycogen phosphorylase were differentially expressed in different species of pig. These results suggested that meat quality of porcine longissimus dorsi might be associated with these differential proteins.5.The amino contents were detected according different postmortem time, using the JH and DLY meat as materials. Results showed that none of the 17 kinds of Amino have any pertinence with the meat quality.