Samgina Tatiana Y, Artemenko Konstantin A, Gorshkov Vladimir A, Poljakov Nikita B, Lebedev Albert T
Chemistry Department, Moscow State University, Moscow, Russia.
J Am Soc Mass Spectrom. 2008 Apr;19(4):479-87. doi: 10.1016/j.jasms.2007.12.010. Epub 2008 Jan 11.
Five natural peptides isolated from ranid skin secretions of European frog species of Rana ridibunda and Rana arvalis (molecular masses 3516, 2674, 2636, 1874, and 1810 Da) were studied by MALDI-TOF/TOF to compare two procedures of disulfide bond cleavage: (1) performic oxidation and (2) reduction/carboxamidomethylation. The processes are relevant for the elucidation of the amino acid sequence inside the seven-member cystine ring at the C-terminus. The results clearly demonstrated that oxidation of the disulfide bond led to notably higher abundances of b- and y-ions, corresponding to the C-terminal peptide bonds, than reduction/carboxamidomethylation. This conclusion is true for all five peptides studied. Besides that, the oxidation procedure is simpler than carboxamidomethylation, as it is a one-step process with no purification required. The oxidation is more reproducible. The results were similar each time the peptide was subjected to the process. It was successfully applied to all five peptides while reduction/carboxamidomethylation failed in the case of brevinin-1Ra, despite all variations of reaction conditions.
对从欧洲蛙类林蛙（Rana ridibunda）和草蛙（Rana arvalis）的皮肤分泌物中分离出的5种天然肽（分子量分别为3516、2674、2636、1874和1810 Da）进行了基质辅助激光解吸电离飞行时间串联质谱（MALDI-TOF/TOF）研究，以比较两种二硫键裂解方法：（1）过甲酸氧化和（2）还原/羧甲基化。这些过程对于阐明C端七元胱氨酸环内的氨基酸序列至关重要。结果清楚地表明，与还原/羧甲基化相比，二硫键氧化导致对应于C端肽键的b离子和y离子丰度显著更高。这一结论适用于所研究的所有5种肽。除此之外，氧化方法比羧甲基化更简单，因为它是一步法，无需纯化。氧化的重现性更高。每次对肽进行该过程时结果都相似。它成功应用于所有5种肽，而在brevinin-1Ra的情况下，尽管反应条件有所变化，但还原/羧甲基化仍失败了。
