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Amino Acid Number (amino + acid_number)
Selected AbstractsStructure investigation of Maltacine C1a, C1b, C2a and C2b,cyclic peptide lactones of the Maltacine complex from Bacillus subtilisJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 10 2005Gunnar Hagelin Abstract A new complex of cyclic peptide lactone antibiotics from Bacillus subtilis, which we named Maltacines, has recently been described. The structure elucidation of four of them is reported in this paper. The amino acid sequences and structures of the peptides were found by MSn of the ring-opened linear peptides, which gave uninterrupted sequences of Bn and Y,n ions. The identities of three unknown residues in the sequences were solved by a combination of derivatisation with phenylisothiocyanate (PITC), high-resolution mass spectrometry and H/D exchange. The nature and position of the cyclic structure was disclosed by a chemo-selective ring opening with Na18OH and was found to be a lactone formed between a hydroxyl of residue number 4 and the C -terminal amino acid number 12. For verification of the structure of the B2+ ion, peptides with different combinations of P/Q and P/K at the N -terminus were synthesised. The structure of the four peptides were found to be: C1a and C2a: cyclo-4,12(P-Q-Y-Adip-V-E-T-Y-Orn-103-Y-I-OH) and C1b/C2b: cyclo-4,12(P-Q-Y-Adip-V-E-T-Y-K-103-Y-I-OH). Adip = aminodihydroxy pentanoic acid. Copyright © 2005 John Wiley & Sons, Ltd. [source] Structure investigation of Maltacine D1a, D1b and D1c,cyclic peptide lactones of the Maltacine complex from Bacillus subtilisJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 10 2005Gunnar Hagelin Abstract A new complex of cyclic peptide lactone antibiotics from Bacillus subtilis, which we named Maltacines has recently been described. The structure elucidation of three of them is reported in this paper. The amino acid sequences and structures of the peptides were found by MSn of the ring-opened linear peptides that gave uninterrupted sequences of Bn and Y,n ions. The identities of four unknown residues in the sequences were solved by a combination of derivatisation with phenylisothiocyanate (PITC), high-resolution mass spectrometry and H/D exchange. The nature and position of the cyclic structure was disclosed by a chemo-selective ring opening with Na18OH and was found to be a lactone formed between a hydroxyl of residue number 4 and the C -terminal amino acid number 12. For verification of the structure of the B2+ ion, peptides with different combinations of P/Q and P/K at the N -terminus were synthesized. The structures of the four peptides is tentatively suggested to be: D1a: cyclo(4,12)-P-Q-Y-Adip-A-E-T-Y-Orn-HGly-Y-I-OH, D1b: cyclo(4,12)-P-Q-Y-Adip-A-E-T-Y-Orn-S-Y-I-OH and D1c: cyclo(4,12)-P-Q-Y-Adip-A-E-T-Y-K-S-Y-I-OH. Adip = aminodihydroxy pentanoic acid and HGly = hydroxyglycine. Copyright © 2005 John Wiley & Sons, Ltd. [source] Mass spectrometric investigation of Maltacines E1a and E1b,two members of the Maltacine family of peptide antibioticsRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 24 2005Gunnar Hagelin We have recently described the discovery of the Maltacines,a new family of cyclic peptide antibiotics from Bacillus subtilis. In this paper the mass spectrometric characterisation of two of the members is reported. A chemoselective ring opening with base to give the linear peptides was necessary before mass spectrometric characterisation could be performed. MSn of the singly and doubly charged protonated molecules gave uninterrupted series of Bn and Y,n ions that allowed determination of the amino acid sequence. By using a combination of derivatisation with phenylisothiocyanate (PITC), high-resolution mass spectrometry and H/D exchange, the identities of three unknown residues were determined. The nature and position of the cyclic structure were disclosed by a chemoselective ring opening with Na18OH and it was found to be a lactone formed between a hydroxyl of residue number 4 and the C-terminal amino acid number 12. Peptides with different combinations of P/Q and P/K at the N-terminus were synthesised to verify the sequence of the N-terminal B2 ion. The structure of the two peptides is proposed to be: E1a: cyclo-4,12(P-Q-Y-Adip-V-E-T-Y-Orn-S-Y-I-OH) and E1b: cyclo-4,12(P-Q-Y-Adip-V-E-T-Y-K-S-Y-I-OH). Adip,=,(2-amino-4,5-dihydroxypentanoic acid). Copyright © 2005 John Wiley & Sons, Ltd. [source] 4265: Inhibitory isoforms of VEGF in uveal melanomaACTA OPHTHALMOLOGICA, Issue 2010SE COUPLAND Purpose Uveal melanoma (UM) affects around 600 new patients in the UK each year with half of these being treated at the Liverpool Ocular Oncology Centre. UM is an unusual tumour in that gross chromosomal abnormalities are strongly associated with metastatic spread, especially monosomy 3 & chromosome 8q gain. Mechanisms that underlie this remain unclear. Methods Angiogenesis is a requirement for tumour survival & metastasis. Vascular Endothelial Growth Factor (VEGF) is known to be the most potent stimulator of angiogenesis and increased expression of VEGF-A is linked to enhanced metastatic potential in UM. Treatment with bevacizumab (anti-VEGF therapy) suppresses hepatic micrometastasis of ocular melanoma cells in animal models. However, VEGF-A data in UM are variable, with some studies demonstrating no correlation between VEGF-A expression and metastasis or survival. Results VEGF-A was accepted as a single pro-angiogenic family of protein isoforms generated from alternatively spliced mRNA (VEGF189, VEGF165 etc). However, recently a family of sister isoforms named VEGFxxxb, where xxx is the amino acid number and b a different six C-terminus amino acids (VEGF189b, VEGF165b) has been discovered. The VEGFxxxb variants are exactly the same size as pro-angiogenic VEGFxxx, yet are antiangiogenic. VEGF165b is down-regulated in primary cutaneous melanoma that later metastasises, and over-expression of VEGFxxxb isoforms confers a protective anti-tumour effect. Conclusion Immunohistochemical expression of pro- and anti-angiogenic VEGF-A in 19 UM was assessed using pan-VEGF-A and VEGF165b specific antibodies. A statistically significant reduction in expression of VEGF165b was observed in monosomy 3 UM (non-parametric ANOVA; p<0.05). This suggests that VEGF165b expression may be a useful predictor of UM metastasis. [source] | ||||||||||