Humayun Mohammad A, Elango Rajavel, Moehn Soenke, Ball Ronald O, Pencharz Paul B
Research Institute, Hospital for Sick Children, Toronto, ON, Canada M5G 1X8.
J Nutr. 2007 Aug;137(8):1874-9. doi: 10.1093/jn/137.8.1874.
Our objective was to determine the metabolic availability (MA) of sulfur amino acids in dietary proteins using the indicator amino acid oxidation (IAAO) technique. Five to seven men received graded levels (20, 40, 60, and 70%) of the mean total sulfur amino acid (TSAA) requirement of 13 mg x kg(-1) x d(-1) as a crystalline AA mixture, casein, and soy protein isolate (SPI) (40, 50, 60, and 70%), respectively. Five of these subjects received 40% of TSAA requirement from SPI supplemented with methionine to the level of 40% of requirement. These 5 subjects also repeated the level of 60% TSAA requirements from both casein and SPI to assess repeatability. The mean MA of TSAA from SPI (71.8 +/- 3.6%) was lower than from casein (87.4 +/- 3.8%, P < 0.05). Supplementation of SPI with methionine decreased the IAAO (11.5 +/- 0.3% administered dose) compared with unsupplemented SPI (12.8 +/- 0.5% administered dose, P < 0.05). IAAO was similar for repeated measurements of casein and SPI, respectively, at the 60% TSAA intake level (10.8 +/- 1.0 vs. 10.7 +/- 1.2% for casein; 12.7 +/- 1.3 vs. 12.9 +/- 2.6% for SPI). In conclusion, the IAAO technique can be used to determine the MA of AA for protein synthesis in test proteins for humans.
我们的目标是使用指示性氨基酸氧化（IAAO）技术来确定膳食蛋白质中含硫氨基酸的代谢可用性（MA）。5至7名男性分别摄入平均总含硫氨基酸（TSAA）需求量13 mg·kg⁻¹·d⁻¹的分级水平（20%、40%、60%和70%）的结晶氨基酸混合物、酪蛋白和大豆分离蛋白（SPI）（分别为40%、50%、60%和70%）。其中5名受试者从补充蛋氨酸至需求量40%水平的SPI中摄入40%的TSAA需求量。这5名受试者还重复摄入酪蛋白和SPI中60%的TSAA需求量水平，以评估重复性。SPI中TSAA的平均MA（71.8±3.6%）低于酪蛋白（87.4±3.8%，P<0.05）。与未补充蛋氨酸的SPI相比，补充蛋氨酸降低了IAAO（给药剂量的11.5±0.3%）（未补充蛋氨酸的SPI为给药剂量的12.8±0.5%，P<0.05）。在60%TSAA摄入量水平下，酪蛋白和SPI重复测量的IAAO相似（酪蛋白为10.8±1.0%对10.7±1.2%；SPI为12.7±1.3%对12.9±2.6%）。总之，IAAO技术可用于确定人类测试蛋白质中用于蛋白质合成的氨基酸的MA。
