caa a22 4500 477136915 CHVBK 20180405111721.0 cr unu---uuuuu 170330e19970101xx s 000 0 eng 10.1007/BF00127967 doi (NATIONALLICENCE)springer-10.1007/BF00127967 Characterization of synthetic peptide byproducts from cyclization reactions using on-line HPLC-ion spray and tandem mass spectrometry [Elektronische Daten] [Seksiri Arttamangkul, Brian Arbogast, Douglas Barofsky, Jane Aldrich] Summary: The cyclization of a linear dynorphin A (Dyn A) analogue to give the lactam derivative cyclo[d-Asp2, Dap5]Dyn A(1-13)NH2 (where Dap=α,β-diaminopropionic acid) was studied to evaluate the usefulness of different coupling reagents for side chain to side chain lactam formation. This cyclization proved to be difficult and yielded substantial byproducts that varied depending upon the activating reagent used. On-line HPLC-ion spray mass spectrometry was more practical and useful than conventional HPLC alone for characterizing the products of these cyclization reactions. Peptide byproducts could be identified from the series of multiply charged ions observed, even when some of these peptides eluted from the HPLC with similar retention times. In addition to the desired cyclic peptide, the peptide byproducts observed following the cyclization using BOP (benzotriazol-1-yl-oxy-tris(dimethylamino)phosphonium hexafluorophosphate) were the linear peptide, the cyclic dimeric peptide and the linear peptide resulting from aspartimide rearrangement. The peptide byproducts obtained following cyclization using HATU (O-(7-azabenzotriazol-1-yl)-1,1,3,3-tetramethyluronium hexafluorophosphate) and HAPyU (O-(7-azabenzotriazol-1-yl)-1,1,3,3-bis(tetramethylene)uronium hexafluorophosphate) were predominantly linear tetramethylguanidinium (Tmg) and dipyrrolidinylguanidinium (Dpg) derivatives resulting from alkylation of the side chain of Dap by HATU and HAPyU, respectively; in addition to monomeric guanidinium derivatives, dimeric and aspartimide-containing peptides were also produced. Peptide sequencing by ion spray tandem mass spectrometry was performed to confirm the structure of both pure peptides and peptide byproducts in the crude samples. A unique fragmentation for the β,γ-bond of the Dap side chain was demonstrated and could be used to identify linear peptide byproducts. The distinctive fragment ions from this cleavage were also observed for the peptides containing the Tmg and Dpg functionalities on the Dap side chain. ESCOM Science Publishers B.V., 1997 Aspartimide rearrangement nationallicence BOP nationallicence Dipyrrolidinylguanidinium nationallicence Dynorphin A derivative nationallicence HAPyU nationallicence HATU nationallicence Tetramethylguanidinium nationallicence Arttamangkul Seksiri College of Pharmacy, Oregon State University, 97331, Corvallis, OR, U.S.A. aut Arbogast Brian Department of Agricultural Chemistry, Oregon State University, 97331, OR, U.S.A. aut Barofsky Douglas Department of Agricultural Chemistry, Oregon State University, 97331, OR, U.S.A. aut Aldrich Jane Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland at Baltimore, 20 North Pine Street, 21201, Baltimore, MD, U.S.A. aut Letters in Peptide Science Kluwer Academic Publishers 3/6(1997-01-01), 357-370 0929-5666 3:6<357 1997 3 10989 https://doi.org/10.1007/BF00127967 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00127967 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Arttamangkul Seksiri College of Pharmacy, Oregon State University, 97331, Corvallis, OR, U.S.A aut NATIONALLICENCE 700 1- Arbogast Brian Department of Agricultural Chemistry, Oregon State University, 97331, OR, U.S.A aut NATIONALLICENCE 700 1- Barofsky Douglas Department of Agricultural Chemistry, Oregon State University, 97331, OR, U.S.A aut NATIONALLICENCE 700 1- Aldrich Jane Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland at Baltimore, 20 North Pine Street, 21201, Baltimore, MD, U.S.A aut NATIONALLICENCE 773 0- Letters in Peptide Science Kluwer Academic Publishers 3/6(1997-01-01), 357-370 0929-5666 3:6<357 1997 3 10989 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer