Walter A W, Henle T, Haessner R, Klostermeyer H
Lehrstuhl für Milchwissenschaft, Technische Universität München, Freising-Weihenstephan, Germany.
Z Lebensm Unters Forsch. 1994 Sep;199(3):243-7. doi: 10.1007/BF01193454.
From reaction mixtures consisting of N-acetyldehydroaminobutyric acid methyl ester and N alpha-acetyl-L-lysine or N alpha-acetyl-L-histidine, respectively, distinct amounts of the cross-link amino acids N epsilon-(2-amino-2-carboxy-1-methyl-ethyl)-L-lysine (lysinomethylalanine, LMeAL) and N tau-(2'-amino-2'-carboxy-1'-methyl-ethyl)-L-histidine (histidinomethylalanine, HMeAL) were isolated via preparative ion-exchange chromatography and identified by 1H- and 13C-nuclear magnetic resonance. In the amino acid chromatogram, both compounds eluted clearly separated from other basic amino acids. However, neither LMeAL nor HMeAL could be detected in numerous acid hydrolysates of a range of milk products. In model studies, threonine showed a significantly lower tendency for an alkali-induced beta-elimination reaction compared to serine. The reactivity of the resulting dehydroaminobutyric acid towards nucleophiles was more than tenfold lower as compared to dehydroalanine. Thus, the formation of LMeAL as well as of HMeAL during food processing is negligible.
分别由N - 乙酰脱氢氨基丁酸甲酯与Nα - 乙酰 - L - 赖氨酸或Nα - 乙酰 - L - 组氨酸组成的反应混合物中，通过制备型离子交换色谱法分离出不同量的交联氨基酸Nε - (2 - 氨基 - 2 - 羧基 - 1 - 甲基 - 乙基) - L - 赖氨酸（赖氨酸甲基丙氨酸，LMeAL）和Nτ - (2'-氨基 - 2'-羧基 - 1'-甲基 - 乙基) - L - 组氨酸（组氨酸甲基丙氨酸，HMeAL），并通过1H - 和13C - 核磁共振进行鉴定。在氨基酸色谱图中，这两种化合物与其他碱性氨基酸明显分离洗脱。然而，在一系列奶制品的大量酸水解产物中均未检测到LMeAL和HMeAL。在模型研究中，与丝氨酸相比，苏氨酸碱诱导的β - 消除反应趋势明显更低。与脱氢丙氨酸相比，生成的脱氢氨基丁酸对亲核试剂的反应性低十余倍。因此，食品加工过程中LMeAL和HMeAL的形成可忽略不计。
