摘要
本文用HPLC分离五肽胃泌素(Pentagastrin,Boc-β-Ala-Trp-Met-Asp-Phe·NH_2,PG_(1-5))及其N-端无保护基的TFA·五肽(β-Ala-Trp-Met-Asp-Pne·NH_2·TFA,TFA·PA_(1-5))被胃泌酸细胞膜和肝匀浆降解之产物,并对它们的氨基酸组成作了分析,又用薄层层析作了进一步验证,从而提出了酶促降解时可能的酶切位点。实验结果表明,N-端的Boc-基团能大幅度增加对酶降解的抵抗力,这从一个方面解释了为什么商品五肽胃泌素的泌酸活性大于其它胃泌素类似物的原因。
High performance liquid chromatography (HPLC) was used to isolate the fragments which were formed during incubation of pentagastrin(Boc-β-Ala-Trp-Met-Asp-Phe·2NH2) and its analog (β-Ala-Trp-Met-Asp-Phe·NH2·TFA) with rat stomach oxyntic gland membranes and liver homogenate.The degradation products were analysed for amino acid components and further characterized fay thin-chromatography on sillican G-60.The major cleavage sites of pentagastrin and its analog were established The results also indicated that Boc-proteeting group does resist 'the degradation of pentagastrin either by membrane or by liver homogenate.It may be a reason why the acid stimulatory activity of pentagastrin is much higher than that of the other gastrin analogs.
