title: Further characterization of glycine-containing microcystins from the McMurdo dry Valleys of Antarctica.
abstract: Microcystins are hepatotoxic cyclic peptides produced by several cyanobacterial genera worldwide. In 2008, our research group identified eight new glycine-containing microcystin congeners in two hydro-terrestrial mat samples from the McMurdo Dry Valleys of Eastern Antarctica. During the present study, high-resolution mass spectrometry, amino acid analysis and micro-scale thiol derivatization were used to further elucidate their structures. The Antarctic microcystin congeners contained the rare substitution of the position-1 ᴅ-alanine for glycine, as well as the acetyl desmethyl modification of the position-5 Adda moiety (3S-amino-9S-methoxy-2S,6,8S-trimethyl-10-phenyldeca-4E,6E-dienoic acid). Amino acid analysis was used to determine the stereochemistry of several of the amino acids and conclusively demonstrated the presence of glycine in the microcystins. A recently developed thiol derivatization technique showed that each microcystin contained dehydrobutyrine in position-7 instead of the commonly observed N-methyl dehydroalanine.
authors: Cawthron Institute, Private Bag 2, Nelson 7010, New Zealand. jonathan.puddick@cawthron.org.nz.
authors: Jonathan
authors: J
authors: Puddick
authors: Department of Chemistry, School of Science, University of Waikato, Private Bag 3105, Hamilton 3240, New Zealand. m.prinsep@waikato.ac.nz.
authors: Michèle R
authors: MR
authors: Prinsep
authors: Cawthron Institute, Private Bag 2, Nelson 7010, New Zealand. d.hamilton@waikato.ac.nz.|Environmental Research Institute, University of Waikato, Private Bag 3105, Hamilton 3240, New Zealand. d.hamilton@waikato.ac.nz.
authors: Susanna A
authors: SA
authors: Wood
authors: Department of Biological Sciences, School of Science, University of Waikato, Private Bag 3105, Hamilton 3240, New Zealand. caryc@waikato.ac.nz.
authors: Stephen Craig
authors: SC
authors: Cary
authors: Environmental Research Institute, University of Waikato, Private Bag 3105, Hamilton 3240, New Zealand. d.hamilton@waikato.ac.nz.
authors: David P
authors: DP
authors: Hamilton
authors: Cawthron Institute, Private Bag 2, Nelson 7010, New Zealand. pth_consultancy@xtra.co.nz.
authors: Patrick T
authors: PT
authors: Holland
mesh_terms: D000864:Antarctic Regions; D002851:Chromatography, High Pressure Liquid; D000458:Cyanobacteria / Q000254:growth & development*; D004784:Environmental Monitoring / Q000379:methods*; D005998:Glycine / Q000737:chemistry*; D052998:Microcystins / Q000737:chemistry / Q000302:isolation & purification*; D008968:Molecular Conformation; D008970:Molecular Weight; D020539:Sequence Analysis, Protein; D021241:Spectrometry, Mass, Electrospray Ionization; D053719:Tandem Mass Spectrometry
chemical_list: D052998:Microcystins; D005998:Glycine