title: Isolation, primary sequence determination, and disulfide bond structure of cyanovirin-N, an anti-HIV (human immunodeficiency virus) protein from the cyanobacterium Nostoc ellipsosporum.
abstract: A novel anti-HIV protein, cyanovirin-N (CV-N), was isolated from an aqueous cellular extract of the cultured cyanobacterium (blue-green alga) Nostoc ellipsosporum, purified by reverse-phase HPLC, and sequenced by N-terminal Edman degradation of the intact protein and peptide fragments produced by endoproteinase digestions. CV-N consists of a single 101 amino acid chain which exhibits significant internal sequence duplication, but no significant homology to previously described proteins or to the transcription products of known nucleotide sequences. Alignment of residues 1-50 with residues 51-101 reveals 13 conservative amino acid changes as well as direct homology between 16 amino acid residues. CV-N contains four cysteines which form two intrachain disulfide bonds. The positions of the disulfide linkages were established by fast atom bombardment mass spectral studies of peptide fragments generated by a tryptic digestion of the native protein. Reductive cleavage of these crosslinks resulted in loss of anti-HIV activity.
authors.affiliation: Laboratory of Drug Discovery Research and Development, National Cancer Institute, Frederick Cancer Research and Development Center, Maryland 21702-1201, USA.
authors.forename: K R
authors.initials: KR
authors.lastname: Gustafson
authors.forename: R C
authors.initials: RC
authors.lastname: Sowder
authors.forename: L E
authors.initials: LE
authors.lastname: Henderson
authors.forename: J H
authors.initials: JH
authors.lastname: Cardellina
authors.forename: J B
authors.initials: JB
authors.lastname: McMahon
authors.forename: U
authors.initials: U
authors.lastname: Rajamani
authors.forename: L K
authors.initials: LK
authors.lastname: Pannell
authors.forename: M R
authors.initials: MR
authors.lastname: Boyd
mesh_terms: D000595:Amino Acid Sequence; D019380:Anti-HIV Agents / Q000737:chemistry* / Q000302:isolation & purification* / Q000494:pharmacology; D001426:Bacterial Proteins / Q000737:chemistry* / Q000302:isolation & purification* / Q000502:physiology; D002352:Carrier Proteins / Q000737:chemistry* / Q000302:isolation & purification* / Q000502:physiology; D002851:Chromatography, High Pressure Liquid; D000458:Cyanobacteria / Q000737:chemistry* / Q000254:growth & development; D004220:Disulfides / Q000737:chemistry* / Q000378:metabolism; D019791:Guanidine; D006146:Guanidines / Q000494:pharmacology; D006801:Humans; D013058:Mass Spectrometry; D008623:Mercaptoethanol / Q000494:pharmacology; D008969:Molecular Sequence Data; D016339:Spectrometry, Mass, Fast Atom Bombardment
chemical_list: D019380:Anti-HIV Agents; D001426:Bacterial Proteins; D002352:Carrier Proteins; D004220:Disulfides; D006146:Guanidines; C107733:cyanovirin N; D008623:Mercaptoethanol; D019791:Guanidine