Power D M, Dimaline R, Balaspiri L, Dockray G J
MRC Secretory Control Research Group, Physiological Laboratory, University of Liverpool, U.K.
Biochim Biophys Acta. 1988 May 18;954(2):141-7. doi: 10.1016/0167-4838(88)90064-7.
An antiserum, L221, has been developed that is specific for the C-terminal region of the N-terminal tridecapeptide (i.e., 1-13) fragment of the acid-stimulating hormone, G17. In contrast to N-terminal G17 antisera previously used to estimate 1-13 G17, L221 does not cross-react with other N-terminal gastrin fragments or with C-terminal extensions of G17. Using L221 in conjunction with conventional gastrin antisera, and reversed-phase HPLC, it has been possible to identify in addition to 1-13 G17 a further, formerly unrecognised gastrin fragment, 1-11 G17, in stomach extracts. The production of 1-13 G17, 1-11 G17 and other gastrin forms such as the biologically active hexapeptide G6 which is known to occur naturally cannot be explained by tryptic cleavage of progastrin. Instead, their biosynthesis could be explained by the actions of an enzyme with an endopeptidase 24.11-like specificity. In porcine antrum, unsulphated and sulphated G17 are present in similar amounts, but unsulphated 1-13 G17 was about twice as abundant as sulphate 1-13 G17. This is consistent with previous in vitro findings that endopeptidase 24.11 has a higher affinity for the Ala-11-Tyr-12 and Gly-13-Trp-14 bonds in unsulphated G17, than in sulphated G17. The results suggest a novel albeit minor, processing pathway for gastrin biosynthesis in pig antrum involving an enzyme resembling endopeptidase 24.11.
已研制出一种抗血清L221，它对酸刺激激素G17的N端十三肽（即1 - 13）片段的C端区域具有特异性。与先前用于估计1 - 13 G17的N端G17抗血清不同，L221不会与其他N端胃泌素片段或G17的C端延伸片段发生交叉反应。将L221与传统的胃泌素抗血清以及反相高效液相色谱法结合使用，除了1 - 13 G17之外，还能够在胃提取物中鉴定出另一种以前未被识别的胃泌素片段1 - 11 G17。1 - 13 G17、1 - 11 G17以及其他胃泌素形式（如已知天然存在的具有生物活性的六肽G6）的产生不能用胃泌素原的胰蛋白酶裂解来解释。相反，它们的生物合成可以用一种具有内肽酶24.11样特异性的酶的作用来解释。在猪胃窦中，未硫酸化和硫酸化的G17含量相似，但未硫酸化的1 - 13 G17的含量约为硫酸化的1 - 13 G17的两倍。这与先前的体外研究结果一致，即内肽酶24.11对未硫酸化的G17中Ala - 11 - Tyr - 12和Gly - 13 - Trp - 14键的亲和力高于硫酸化的G17。结果表明，在猪胃窦中存在一种新的、尽管较小的胃泌素生物合成加工途径，涉及一种类似于内肽酶24.11的酶。
