Péter A, Devadder S, Laus G, Tourwé D
Department of Inorganic and Analytical Chemistry, Attila József University, Szeged, Hungary.
J Chromatogr A. 1996 Apr 5;729(1-2):137-42. doi: 10.1016/0021-9673(95)00948-5.
Several agonists of luteinizing hormone-releasing hormone (LHRH) are currently used for different therapeutic purposes, but relatively little is known about their metabolic fate after administration. This paper describes the application of high-performance liquid chromatography combined with off-line fast atom bombardment mass spectrometry to identify the degradation products resulting from the incubation of LHRH analogues with proteolytic enzymes. Three analogues, containing a psi(E,CH = CH) pseudo-peptide bond were synthesized and afforded to the assay to determine the resistance against alpha-chymotrypsin and subtilisin: [Tyr5 psi(E,CH = CH)Gly6]LHRH, [Gly6 psi(E,CH = CH)D,L-Leu7]LHRH and [Pro9 psi(E,CH = CH)Gly10 ]LHRH. The pattern of peptide metabolites identified by this method indicates that alpha-chymotrypsin degrades LHRH analogues at the Trp3-Ser4 and Tyr5-Gly6 bond, while subtilisin hydrolyzes only the Tyr5-Gly6 linkage. The results also indicate a possible stabilization of native amide bonds against enzymatic degradation by neighbouring psi(E, CH = CH) modifications.
目前，几种促黄体生成激素释放激素（LHRH）激动剂被用于不同的治疗目的，但关于它们给药后的代谢命运却知之甚少。本文描述了高效液相色谱结合离线快速原子轰击质谱法在鉴定LHRH类似物与蛋白水解酶孵育产生的降解产物中的应用。合成了三种含有ψ（E，CH = CH）假肽键的类似物，并用于测定其对α-胰凝乳蛋白酶和枯草杆菌蛋白酶的抗性：[Tyr5ψ（E，CH = CH）Gly6]LHRH、[Gly6ψ（E，CH = CH）D，L-Leu7]LHRH和[Pro9ψ（E，CH = CH）Gly10]LHRH。通过该方法鉴定的肽代谢物模式表明，α-胰凝乳蛋白酶在Trp3-Ser4和Tyr5-Gly6键处降解LHRH类似物，而枯草杆菌蛋白酶仅水解Tyr5-Gly6键。结果还表明，相邻的ψ（E，CH = CH）修饰可能会使天然酰胺键对酶促降解具有稳定性。
