| Collagen, as the main component of intramuscular connective tissues, the various characteristics of it would affect the quality of meat during growth of animals. Ujumqin Sheep (6,9,12,18-month-old) on natural grazing were selected in this study. After being extracted from skeletal muscle (semitendinosus muscle and longissimus dorsi muscle), firstly, collagen Ⅰ and collagen Ⅲ were identified by SDS-PAGE and fourier transform infrared (FTIR) spectra. Secondly, amino acid compositions of collagen were determined by amino acid analyzer. Then the thermal denaturation temperature of collagen was analyzed using differential scanning calorimetry (DSC), and the relationship between the content of imino acids was analysed by Pearson correlation coefficient. And the heat-soluble collagen was investigated using UV spectrophotometry. Lastly, after being extracted from skeletal muscle, the content of pyridinoline in endomysium and perimysium was accounted using high performance liquid chromatography respectively. The results are as follows:The total content of amino acids, imino acids and the content of hydroxyproline in collagen Ⅰ were all increased significantly during growth of sheep (P<0.05). The total content of amino acids in collagen Ⅲ were decreased significantly (P<0.05). The content of imino acids were increased firstly, then decreased significantly (P<0.05). The content of hydroxyproline in collagen Ⅲ was increased significantly during growth of sheep (P<0.05).During growth of Ujumqin sheep, thermal denaturation temperature of collagen Ⅰ and collagen III were both increased gradually significantly (P<0.01). There was a significant and positive correlation between thermal denaturation temperature of collagen Ⅰ and the content of imino acid (P<0.05). Thermal denaturation temperature of collagen Ⅲ was positively correlated with the content of imino acid (P<0.05).Thermal solubility of collagen Ⅰ from skeletal muscle was decreased significantly during growth of sheep (P<0.05), the same to thermal solubility of collagen Ⅲ from longissimus dorsi muscle. Thermal solubility of collagen Ⅲ from semitendinosus muscle was also decreased significantly during growth of sheep, except between aged 12-month one and aged 6-month one, aged 9-month one (P<0.05). Thermal solubility of collagen I was higher than that of collagen III of the same age significantly (P<0.05).The content of pyridinoline in endomysium increased significantly during growth of sheep (P<0.05), and the amount in perimysium also increased gradually significantly (P<0.05), except between aged 6-month one and aged 9-month one. The content of pyridinoline in endomysium was higher than that in perimysium. Similarly, the content of pyridinoline from semitendinosus muscle was higher than that from longissimus dorsi muscle (P<0.05).This study explains the characteristics of collagen Ⅰ and collagen Ⅲ in intramuscular connective tissues during growth of Ujumqin sheep, which provides a theoretical foundation for explaining the effect of intramuscular connective tissues and collagen on meat quality. |
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