Protein-bound D-amino acids, and to a lesser extent lysinoalanine, decrease true ileal protein digestibility in minipigs as determined with 15N-labeling
Protein-bound D-amino acids, and to a lesser extent lysinoalanine, decrease true ileal protein digestibility in minipigs as determined with 15N-labeling
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DOI：
10.1093/jn/130.8.2026
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发表时间：
2000-08-01
影响因子：
4.2
通讯作者：
Hagemeister, H
中科院分区：
文献类型：
--
作者：
de Vrese, M;Frik, R;Hagemeister, H
食物的加热和碱处理可能会增加蛋白质结合的D-氨基酸和交联剂（如赖氨酸丙氨酸（LAL））的浓度。为了检查蛋白质处理如何影响消化率，纯化的测试餐[总蛋白质150 g/kg干物质（DM），0.44 MJ/（kg BW 0.75. d）]，含有（g/kg DM）酪蛋白，75; β-乳球蛋白，50;或小麦蛋白，40。每个都是N-15标记的。测试蛋白质以其天然形式或在65 ° C，pH 10.5-11.5下处理6或24小时后使用。每餐饲喂9只成年小型猪（双重完全交叉分类）。食糜连续收集超过33小时餐后通过T-瘘管在回肠末端，和试验蛋白质和单个L-和D-氨基酸的消化率计算的基础上回收的N-15和食糜中的相应的氨基酸。酪蛋白、β-乳球蛋白或小麦蛋白处理24小时增加了D-氨基酸残基的水平。L-天冬酰胺和天冬氨酸（L-Asx）特别敏感;分别有14.7 +/- 0.4、11.7 +/- 0.2和11.0 +/-0.9%发生外消旋化。LAL水平平行增加;分别有11.7 +/- 0.3、13.8 +/- 0和14.8 +/-0.0%的总赖氨酸转化为LAL。同时，盲肠前蛋白质消化率分别降低了13.4 +/- 2.3、15.3 +/- 1.4和17.8 +/- 1.2%单位（P < 0.05;平均值+/- SEM，n = 9）。个别L-氨基酸的消化率下降了10- 15%，但L-氨基酸易于消化裂解，如L-苯丙氨酸和L-酪氨酸，不受影响。D-氨基酸和LAL的消化率接近35%。似乎主要是D-氨基酸，并在较小程度上LAL，负责通过干扰消化酶裂解降低消化率。
Heat and alkali treatment of food may increase the concentrations of protein-bound D-amino acids and cross-links such as lysinoalanine (LAL). To examine how protein treatment affects digestibility, purified test meals [total protein 150 g/kg dry matter (DM), 0.44 MJ/(kg BW0.75. d)] were prepared, containing (g/kg DM) casein, 75; beta-lactoglobulin, 50; or wheat protein, 40. Each was N-15-labeled. Test proteins were used either in their native form or after treatment for 6 or 24 h at 65 degrees C, pH 10.5-11.5. Each meal was fed to nine adult miniature pigs (twofold complete cross-classification). Chyme was collected continuously over 33 h postprandially via T-fistulas in the terminal ileum, and digestibilities of test proteins and individual L- and D-amino acids were calculated on the basis of recovery of N-15 and the respective amino acids in the chyme. Treatment of casein, beta-lactoglobulin or wheat protein for 24 h increased levels of D-amino acid residues. L-Asparagine and aspartate (L-Asx) were particularly susceptible; 14.7 +/- 0.4, 11.7 +/- 0.2 and 11.0 +/- 0.9%, respectively, underwent racemization. LAL levels increased in parallel; 11.7 +/- 0.3, 13.8 +/- 0 and 14.8 +/- 0.0%, respectively, of total lysine was converted to LAL. At the same time, prececal protein digestibility was decreased by 13.4 +/- 2.3, 15.3 +/- 1.4 and 17.8 +/- 1.2% units, respectively (P < 0.05; mean +/- SEM, n = 9). Digestibility of individual L-amino acids decreased by 10-15%, but L-amino acids prone to peptic cleavage, such as L-phenylalanine and L-tyrosine, were not affected. Digestibilities of D-amino acids and LAL were similar to 35%. It seems that mainly D-amino acids, and to a lesser extent LAL, were responsible for lower digestibility by interfering with peptic cleavage.