Romagnolo D, Polan C E, Barbeau W E
Department of Dairy Science, College of Agriculture and Life Sciences, Virginia Polytechnic Institute and State University, Blacksburg 24061-0315.
J Dairy Sci. 1994 Apr;77(4):1093-9. doi: 10.3168/jds.S0022-0302(94)77044-2.
Albumin, globulin, and prolamin fractions were extracted from corn meal in water, .5 M NaCl, and 50% (vol/vol) 1-propanol and examined by SDS-PAGE and densitometric scanning to investigate fractional degradation rates of corn proteins. Several protein fractions were identified for globulins, zein prolamins, and glutelins. Ruminal degradability of individual subfractions was evaluated by suspension of corn and corn gluten meal samples in the rumen of lactating dairy cows from 0 to 72 h. Electrophoretic and densitometric analysis of protein residues revealed that the prolamin fraction zein for corn and corn gluten meal was more resistant to ruminal degradation than albumins, globulins, and glutelins. Relative rates of degradation of zein and the fraction containing albumins, globulins, and glutelins were .060, .026, and .018, .015/h for corn and corn gluten meal, respectively. Total degradabilities of corn and corn gluten meal, measured by summation of degradability of subfractional components, were 52.2 and 18.6%. Quantitative measurement of ruminally degradable subfractions and estimation of their degradation rates by electrophoretic and densitometric scanning are useful in understanding ruminal degradability of corn proteins.
从玉米粉中分别用水、0.5M氯化钠和50%（体积/体积）1-丙醇提取白蛋白、球蛋白和醇溶蛋白组分，并通过SDS-PAGE和光密度扫描进行检测，以研究玉米蛋白各组分的降解率。鉴定出了球蛋白、玉米醇溶蛋白和谷蛋白的几个蛋白质组分。通过将玉米和玉米蛋白粉样品在泌乳奶牛瘤胃中悬浮0至72小时，评估各个亚组分的瘤胃降解性。对蛋白质残留进行的电泳和光密度分析表明，玉米和玉米蛋白粉中的醇溶蛋白组分玉米醇溶蛋白比白蛋白、球蛋白和谷蛋白更耐瘤胃降解。玉米醇溶蛋白以及含白蛋白、球蛋白和谷蛋白的组分的相对降解率，玉米和玉米蛋白粉分别为0.060、0.026和0.018、0.015/小时。通过亚组分降解性的总和来衡量，玉米和玉米蛋白粉的总降解率分别为52.2%和18.6%。通过电泳和光密度扫描对瘤胃可降解亚组分进行定量测量并估计其降解率，有助于了解玉米蛋白的瘤胃降解性。
