动物营养学报2017，Vol.29Issue(1)：325-332,8.DOI:10.3969/j.issn.1006-267x.2017.01.037
绵羊瘤胃细菌、原虫蛋白质分解代谢相关酶活力及谷氨酸脱氢酶体系的米氏常数值
Enzyme Activities Related to Protein Catabolism and Km Value of Glutamate Dehydrogenase System in Rumen Bacteria and Protozoa of Sheep
摘要
Abstract
This study was to conducted to determine enzyme activities related to protein catabolism and Km val⁃ue of glutamate dehydrogenase ( GDH) system in rumen bacteria and protozoa of sheep, to provide enzymolo⁃gy reference to explain protein catabolism in rumen bacteria and protozoa of sheep. Six 1⁃year⁃old healthy Chi⁃nese merino sheep (Xinjiang type) [average body weight was (32.00±1.36) kg] were chosen. The sheep were installed with permanent fistula in rumen. Dietary forage to concentrate ratio was 30∶70. Rumen fluid was collected sequentially before feeding ( 0 h) and 1. 5, 3. 0, 6. 0, 9. 0 and 12. 0 h after feeding, respectively, which were repeated 3 times. After centrifugation, crushing liquid of rumen bacteria and protozoa was prepared to determine the activities of enzymes and Km values of GDH system. The results showed as follows: 1) the activities of protease, glutamic⁃pyruvic transaminase (GPT), glutamic oxal(o)acetic transaminase (GOT) and GDH showed an initial increase and then a decrease as the feeding time passed by, and generally reached the maximum at 1.5 h after feeding in rumen bacteria and protozoa crushing liquid of sheep; the contents of glutamate and ammonia ( NH+4 ) contents showed similar tendency. The activities of the four enzymes involved in protein metabolism in rumen protozoa crushing liquid were significantly higher than those in rumen bacteria ( P<0.01) . 2) Glutamate content of rumen protozoa crushing liquid was significantly higher than that of bacte⁃ria ( P<0.01) . Ammonia content of rumen protozoa crushing liquid was significantly higher than that of bacte⁃ria at 1.5, 6.0, 9.0 and 12.0 h ( P<0.05 or P<0.01) . 3) Km values of GDH to NAD in bacteria and protozoa crushing liquid were 2.60×10-7 and 1.48×10-7 mol/L, respectively; those to glutamate in bacteria and proto⁃zoa crushing liquid were 8.41×10-6 and 4.91×10-6 mol/L, respectively;those to NADH in bacteria and proto⁃zoa crushing liquid were 3. 80 × 10-8 and 2. 70 × 10-8 mol/L, respectively; those to α⁃oxoglutarate in bacteria and protozoa crushing liquid were 1.16×10-6 and 2.07×10-6 mol/L, respectively;those to ammonia in bacteria and protozoa crushing liquid were 2.97×10-5 and 1.40×10-5 mol/L, respectively. The results indicate that the activities of protease, GPT, GOT and GDH generally reach the maximum at 1.5 h after feeding, then gradual⁃ly decrease in rumen bacteria and protozoa of sheep; meanwhile, the enzyme activities in protozoa are signifi⁃cantly higher than those in bacteria, and protein catabolism in protozoa is more active than in bacteria;there is not only a transamination mechanism of glutamate, but also a re⁃using ammonia mechanism for synthesis of a⁃mino acids in rumen protozoa.关键词
瘤胃/细菌/原虫/蛋白质分解代谢/酶活力/Km值Key words
rumen/bacteria/protozoa/protein catabolism/enzyme activity/Km value分类
农业科技引用本文复制引用
熊文秀,翟卫爽,屯妮萨·麦提赛伊迪,吴欣,杨开伦..绵羊瘤胃细菌、原虫蛋白质分解代谢相关酶活力及谷氨酸脱氢酶体系的米氏常数值[J].动物营养学报,2017,29(1):325-332,8.基金项目
国家自然基金“瘤胃细菌、原虫内与NAD（P）H相关的几个主要代谢途径及其生理生化功能的研究” （）
