动物的肽吸收机制及组织利用  

Absorption Mechanisms and Tissue Utilization of Peptide Nutrition in Animals

作　　者：李燕[1] 王中华[1] 

机构地区：[1]山东农业大学动物科技学院,泰安271018

出　　处：《动物营养学报》2006年第B12期303-309,共7页CHINESE JOURNAL OF ANIMAL NUTRITION

基　　金：国家"十五"科技攻关奶业专项(2002BA518A16)

摘　　要：已有的研究证实,小肽的消化道吸收机制不同于氨基酸。已发现的吸收机制包括渗透扩散、中间载体转运、通道穿透吸收3种方式。其中,小肽的中间载体转运吸收有2种类型:(1)依赖跨膜的H+浓度梯度,H+/肽共转运子在向吸收细胞内转运分子肽的同时伴随着两个H+的吸收,而跨膜的H+浓度梯度则是依靠耗能的Na+/H+交换子来维持,H+/肽共转运子和Na+/H+交换子在功能上是独立的;(2)肽中间载体转运依赖跨膜的阳离子浓度梯度,而二价阳离子的促吸收作用高于一价阳离子。已知谷胱甘肽是通过第二种转运机制转运的。瘤胃和瓣胃具有很强的小肽吸收能力,可能是反刍动物肽吸收的主要部位,但有关研究的结果差异较大,与动静脉差法的测定误差较大有关。对于体组织肽利用的了解不多,已有的研究表明体组织可以利用小肽,其过程是组织吸收的肽在组织细胞内降解为氨基酸,而后用于蛋白质的合成和分解代谢。Results of previous studies revealed that peptides were absorbed through different mechanisms from those of amino acid in gastrointestinal tract, which were passive diffusion, carrier- mediated absorption, and paracellular absorption. Two types of carrier- meditated peptide transport systems in the membrane of absorption cells of gastrointestinal tract have been identified up to now. One system was H^＋/peptide symporters, which was H^＋ -dependent, and two H^＋ were co-transported with each peptide transported into the absorptive cell. The other system was cation-dependent, and divalent cations were more effective than monovalent cations in promoting peptide absorption. Rumen and omasum might be the main positions of peptide absorption in ruminants as they had been proved that ruminal and omasual epithelium had the greatest capacity in peptide absorption. The amounts of peptide absorbed into the portal blood stream measured by arterial- venous different method varied greatly in different studies, which might be mainly resulted from the system error of the method itself. The tissues absorb peptides from blood stream. It was postulated that these absorbed peptides were hydrolyzed into its constituent amino acids before they were used as precursors of protein synthesis or catabolized in cells of body tissues. [Chinese Journal of Animal Nutrition, 2006,18（Suppl） ：303-309 ]

关 键 词：肽 吸收 组织利用 

分 类 号：S852.2[农业科学—基础兽医学]