Hulshof Tetske G, Rutherfurd Shane M, Sforza Stefano, Bikker Paul, van der Poel Antonius F B, Hendriks Wouter H
Wageningen University & Research , Wageningen Livestock Research, P.O. Box 338, 6700 AH Wageningen, The Netherlands.
Wageningen University & Research , Animal Nutrition Group, P.O. Box 338, 6700 AH Wageningen, The Netherlands.
J Agric Food Chem. 2017 Feb 1;65(4):964-972. doi: 10.1021/acs.jafc.6b03096. Epub 2017 Jan 18.
The specificity of O-methylisourea (OMIU) to bind to the ε-amino group of Lys, an important supposition for the OMIU-reactive Lys analysis of foods, feeds, ingredients, and digesta, was investigated. Crystalline l-Lys incubated under standard conditions with OMIU resulted in low homoarginine recoveries. The reaction of OMIU with the α-amino group of Lys was confirmed by MS analysis, with double derivatized Lys being identified. None of the changes in reaction conditions (OMIU pH, OMIU to Lys ratio, and reaction time) with crystalline l-Lys resulted in 100% recovery of homoarginine. The average free Lys content in ileal digesta of growing pigs and broilers was found to be 13% of total Lys, which could result in a significant underestimation of the reactive Lys content. The reaction of OMIU with α-amino groups may necessitate analysis of free Lys to accurately quantify reactive lysine in samples containing a large proportion of Lys with a free α-amino group.
研究了O-甲基异脲（OMIU）与赖氨酸ε-氨基结合的特异性，这是对食品、饲料、成分和消化物中OMIU反应性赖氨酸进行分析的一个重要假设。在标准条件下，结晶型L-赖氨酸与OMIU孵育后，高精氨酸回收率较低。通过质谱分析证实了OMIU与赖氨酸α-氨基的反应，并鉴定出了双衍生化的赖氨酸。改变结晶型L-赖氨酸的反应条件（OMIU的pH值、OMIU与赖氨酸的比例和反应时间），均无法使高精氨酸的回收率达到100%。结果发现，生长猪和肉鸡回肠消化物中游离赖氨酸的平均含量占总赖氨酸的13%，这可能会导致对反应性赖氨酸含量的严重低估。OMIU与α-氨基的反应可能需要对游离赖氨酸进行分析，以便在含有大量具有游离α-氨基的赖氨酸的样品中准确量化反应性赖氨酸。
