Publication

Abstract : 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.