Comparison of the positive and negative ion electrospray mass spectra of some small peptides containing pyroglutamate

The definitive version may be found at www.wiley.comThe positive ion electrospray mass spectra of [M+H](+) and the negative ion electrospray mass spectra of [M-H](-) ions of selected pyroglutamate containing peptides both provide sequencing data. The negative ion spectra show the normal alpha and beta backbone cleavages in addition to delta and gamma backbone cleavages initiated by the side chains of Glu and Phe residues. For example, the [M-H](-) ion of pGlu Pro Gln Val Phe Val-NH(2) shows delta and gamma peaks at m/z 224 (delta, Gln3), 244 (gamma, Phe4), 451 (delta, Phe4), 471 (gamma, Gln3). Some of the negative ion spectra show unusual grandaughter peaks that originate by alpha and beta, or delta and gamma backbone cleavages of a beta(1) cleavage ion.Pinmanee Boontheung, Craig S. Brinkworth, John H. Bowie, Russell V. Baudinett

Is the Australian Striped Burrowing Frog Litoria alboguttata a member of Litoria or Cyclorana? A profeling study using skin peptides as a probe

This document has been attached with permission from the publisher.The skin secretion of the Striped Burrowing Frog Litoria alboguttata contains the peptides named guttatins 1, 2 and 3. The sequences of these peptides are as follows:- guttatin 1 (GLLDSVL-NH2); guttatin 2 (GLLDNVL-NH2) and guttatin 3 (GLLDTVKGLN-NH2). This peptide profile is different from those of congeners so far studied in that it contains neither neuropeptides nor antibiotic peptides. In contrast, the peptide profile of L. alboguttata is similar to that of Cyclorana australis. In particular, the two peptides in the skin secretion of C. australis correspond to guttatin 1 and GLLDGTVL-NH2. Guttatin 1 is not present in the secretions of the other 22 Litoria species that we have investigated. Peptide profiling indicates that Litoria alboguttata is more closely related to the genus Cyclorana than Litoria. © 2006, Taylor & Francis Group, LLC. All rights reserved.P. Boontheung, Cheng-Wei Gao, C. S. Brinkworth, J.H. Bowie and M.J. Tylerhttp://www.samuseum.sa.gov.au/page/default.asp?site=1&page=Thunde

Activities of seasonably variable caerulein and rothein skin peptides from the tree frogs Litoria splendida and Litoria rothii

Two species of tree frog of the genus Litoria, namely L. splendida and L. rothii have been reported to change the compositions of their host-defence skin peptide profiles in summer and winter. L. splendida produces the potent smooth muscle active caerulein [pEQDY(SO3H)TGWMDF-NH2] in summer, but in winter much of the caerulein is hydrolysed to the less active desulfated form; in addition, caerulein 1.2 [pEQDY(SO3H)TGWFDF-NH2] (which has only some 50% of the smooth muscle activity of caerulein) is released and acts via CCK2R. In contrast, Litoria rothii shows a most unexpected seasonal change of peptides. In summer it exudes caerulein together with a range of potent caerin antimicrobials and nNOS active peptides. In winter, none of the antibiotic or nNOS active caerin peptides are expressed. The major peptides produced by the skin glands in winter are caerulein 1.2 and rothein 1 (SVSNIPESIGF-OH). Like L. splendida, L. rothii has reduced the smooth muscle potency of caerulein by replacing it with caerulein 1.2. Rothein 1 is a lymphocyte proliferator acting via CCK2R. Activity testing and 2D NMR spectra of rothein 1 and some synthetic modifications indicate that both hydrophobic and hydrophilic interactions between rothein 1 and CCK2R are important.Patrick J. Sherman, Rebecca J. Jackway, Emily Nicholson, Ian F. Musgrave, Pinmanee Boontheung and John H. Bowi

Mining proteomic data to expose protein modifications in Methanosarcina mazei strain Gö1.

Proteomic tools identify constituents of complex mixtures, often delivering long lists of identified proteins. The high-throughput methods excel at matching tandem mass spectrometry data to spectra predicted from sequence databases. Unassigned mass spectra are ignored, but could, in principle, provide valuable information on unanticipated modifications and improve protein annotations while consuming limited quantities of material. Strategies to "mine" information from these discards are presented, along with discussion of features that, when present, provide strong support for modifications. In this study we mined LC-MS/MS datasets of proteolytically-digested concanavalin A pull down fractions from Methanosarcina mazei Gö1 cell lysates. Analyses identified 154 proteins. Many of the observed proteins displayed post-translationally modified forms, including O-formylated and methyl-esterified segments that appear biologically relevant (i.e., not artifacts of sample handling). Interesting cleavages and modifications (e.g., S-cyanylation and trimethylation) were observed near catalytic sites of methanogenesis enzymes. Of 31 Methanosarcina protein N-termini recovered by concanavalin A binding or from a previous study, only M. mazei S-layer protein MM1976 and its M. acetivorans C2A orthologue, MA0829, underwent signal peptide excision. Experimental results contrast with predictions from algorithms SignalP 3.0 and Exprot, which were found to over-predict the presence of signal peptides. Proteins MM0002, MM0716, MM1364, and MM1976 were found to be glycosylated, and employing chromatography tailored specifically for glycopeptides will likely reveal more. This study supplements limited, existing experimental datasets of mature archaeal N-termini, including presence or absence of signal peptides, translation initiation sites, and other processing. Methanosarcina surface and membrane proteins are richly modified

Mining proteomic data to expose protein modifications in Methanosarcina mazei strain Gö1.

Proteomic tools identify constituents of complex mixtures, often delivering long lists of identified proteins. The high-throughput methods excel at matching tandem mass spectrometry data to spectra predicted from sequence databases. Unassigned mass spectra are ignored, but could, in principle, provide valuable information on unanticipated modifications and improve protein annotations while consuming limited quantities of material. Strategies to "mine" information from these discards are presented, along with discussion of features that, when present, provide strong support for modifications. In this study we mined LC-MS/MS datasets of proteolytically-digested concanavalin A pull down fractions from Methanosarcina mazei Gö1 cell lysates. Analyses identified 154 proteins. Many of the observed proteins displayed post-translationally modified forms, including O-formylated and methyl-esterified segments that appear biologically relevant (i.e., not artifacts of sample handling). Interesting cleavages and modifications (e.g., S-cyanylation and trimethylation) were observed near catalytic sites of methanogenesis enzymes. Of 31 Methanosarcina protein N-termini recovered by concanavalin A binding or from a previous study, only M. mazei S-layer protein MM1976 and its M. acetivorans C2A orthologue, MA0829, underwent signal peptide excision. Experimental results contrast with predictions from algorithms SignalP 3.0 and Exprot, which were found to over-predict the presence of signal peptides. Proteins MM0002, MM0716, MM1364, and MM1976 were found to be glycosylated, and employing chromatography tailored specifically for glycopeptides will likely reveal more. This study supplements limited, existing experimental datasets of mature archaeal N-termini, including presence or absence of signal peptides, translation initiation sites, and other processing. Methanosarcina surface and membrane proteins are richly modified