De novo sequencing of two novel peptides homologous to calcitonin-like peptides, from skin secretion of the Chinese Frog, Odorrana schmackeri

Publication date: Available online 6 July 2015 Source:EuPA Open Proteomics Author(s): Geisa P.C. Evaristo , Martijn W.H. Pinkse , Tianbao Chen , Lei Wang , Shabaz Mohammed , Albert J.R. Heck , Isabella Mathes , Friedrich Lottspeich , Chris Shaw , Juan Pablo Albar , Peter D.E.M. Verhaert An MS/MS based analytical strategy was followed to solve the complete sequence of two new peptides from frog (O. schmackeri) skin secretion. This involved reduction and alkylation with two different alkylating agents followed by high resolution tandem mass spectrometry. De novo sequencing was achieved by complementary CID and ETD fragmentations of full-length peptides and of selected tryptic fragments. Heavy and light isotope dimethyl labeling assisted with annotation of sequence ion series. The identified primary structures are GCD[I/L]STCATHN[I/L]VNE[I/L]NKFDKSKPSSGGVGPESP-NH2 and SCNLSTCATHNLVNELNKFDKSKPSSGGVGPESF-NH2, i.e. two carboxyamidated 34 residue peptides with an aminoterminal intramolecular ring structure formed by a disulfide bridge between Cys2 and Cys7. Edman degradation analysis of the second peptide positively confirmed the exact sequence, resolving I/L discriminations. Both peptide sequences are novel and share homology with calcitonin, calcitonin gene related peptide (CGRP) and adrenomedullin from other vertebrates. Detailed sequence analysis as well as the 34 residue length of both O. schmackeri peptides, suggest they do not fully qualify as either calcitonin...
Source: EuPA Open Proteomics - Category: Bioinformatics Source Type: research