宰后牦牛肉保水性变化与差异蛋白的生物信息学分析

牦牛肉营养丰富,但保水性较低,影响了食用加工品质。为了探究牦牛肉保水性影响机制,利用蛋白质组学及生物信息学方法对高、低保水性组间差异蛋白质进行了研究。以牦牛背最长肌为实验材料,根据滴水损失和蒸煮损失,将18份样品分为高保水性组（HWHC）和低保水性组（LWHC）,利用双向电泳（2DE）技术筛选出6个差异倍数大于3倍且达到显著水平（P<0.05）的蛋白点,通过基质辅助激光解吸/电离飞行时间（MALDI-TOF/TOF）质谱进行鉴定,并利用生物信息学方法对差异蛋白质进行了疏水性分析和亚细胞定位分析。结果表明,HWHC和LWHC组间的差异蛋白分别是乳酸脱氢酶（LDH）、肌酸激酶M型（CKM）、磷酸丙糖异构酶（TIM）、肌球蛋白轻链（MLC）、肌钙蛋白T（TnT）和热休克蛋白27kDa（HSP27）。对影响牦牛肉蒸煮损失的6种关键蛋白质进行了疏水性分析,结果显示LDH、CKM和TIM蛋白疏水性较高,构成蛋白质的氨基酸的高疏水性可以增强蛋白质和水之间的排斥,这可能是导致牦牛肉中保水性差异的原因之一。亚细胞定位分析显示,差异表达的蛋白质在细胞中分为5个位置,差异蛋白质均位于细胞质和细胞核中。研究结果明确了宰后牦牛肉保水性变化趋势,并通过差异蛋白的生物信息学分析揭示了蛋白质影响牦牛肉保水性的作用机理。

Changes of Postmortem Water-holding Capacity in Yak Muscle and Bioinformatic Analysis of Differentially Abundant Proteins

Yak meat is rich in nutrients, but has low water-holding capacity (WHC), which affects its edible and processing quality. Therefore, control of postmortem juice loss and reduction of economic loss are crucial issues needing urgent resolution in the yak meat processing industry. Existing research suggested that changes in proteins affected the WHC of postmortem muscle, but relevant mechanism was still not entirely clear because of the complexity of protein composition. Thus, it is very important to explore the variation mechanism of postmortem WHC of yak meat by combining multiple analytical and testing methods. Proteomics research combined with bioinformatics approach was studied by comparing high-WHC (HWHC) and low-WHC (LWHC) groups. Based on the data obtained from drip loss and cooking loss, totally 18 longissimus dorsi of yak can be classified into HWHC and LWHC groups. Totally six proteins were found to be abundant differentially between HWHC and LWHC groups and identified by matrix assisted laser desorption ionization time of flight/time of flight (MALDI-TOF/TOF). Matched spots exhibited a three fold or more intensity difference in the meantime associated with 5% statistical significance (P<0.05). Then hydrophobicity analysis and subcellular localization prediction were used to validate the representative proteins. Results showed that differentially abundant proteins were lactate dehydrogenase (LDH), creatine kinase M-type (CKM), triosephosphate isomerase (TIM), myosin light chain (MLC), troponin T (TnT) and heat shock 27kDa (HSP27). The analysis of hydrophobicity performed that LDH, CKM and TIM had more hydrophobic regions. The results showed that the high hydrophobicity could enhance the rejection of protein and water, which might lead to the weak water retention of yak meat. In subcellular localization prediction, the differentially abundant proteins in the cells were divided into five positions. All of the differentially abundant proteins were located in the cytoplasm and nucleus. Accordingly, proteomics and bioinformatics analyses were proven to be excellent tools to quantify the changes of proteins and biological information linked to WHC, and thus helping to explain the processes behind characteristic meat quality traits in yak muscle.