Structural characterization of an unusually stable cyclic peptide, kalata B2 from Oldenlandia affinis.
Kalata peptides are isolated from an African medicinal plant, Oldenlandia affinis, an aqueous decoction of which can be ingested to accelerate uterine contraction during childbirth. The closely packed disulfide core of kalata peptides confers unusual stability against thermal, chemical, and enzymatic degradation. The molecular arrangement may hamper NMR-assisted disulfide connectivity assignment. We have combined NMR with high-resolution mass spectrometry (MS) and MS/MS of native and chemically derivatized kalata B2 to determine its amino acid sequence and disulfide connectivity. Infrared multiphoton dissociation establishes the disulfide bond linkages in kalata B2 as I-IV, II-V and III-VI.
Nair
Sudarslal Sadasivan
SS
National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310, USA.
Romanuka
Julija
J
Billeter
Martin
M
Skjeldal
Lars
L
Emmett
Mark R
MR
Nilsson
Carol L
CL
Marshall
Alan G
AG
D000595:Amino Acid Sequence; D047169:Cyclotides / Q000737:chemistry / Q000302:isolation & purification; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D032067:Oldenlandia / Q000378:metabolism*; D010456:Peptides, Cyclic / Q000737:chemistry* / Q000302:isolation & purification; D011487:Protein Conformation
D047169:Cyclotides; D010456:Peptides, Cyclic; C561323:kalata B2