title: The observation of quasi-molecular ions from a protein neurotoxin (MW 7821) using 127I-plasma desorption mass spectroscopy.
abstract: Fast heavy ions, i.e. 90 MeV 127I from the Uppsala tandem accelerator have been used to desorb and ionize molecules from a cobra venom neurotoxin. The protein is built up by 71 amino acid residues in a single polypeptide chain, tightly cross-linked by 5 disulfide bridges. The molecular weight as confirmed by protein sequence analysis is 7821. The ions were mass analyzed by the time-of-flight technique. This is to our knowledge the largest protein for which it has been possible to detect quasi-molecular ions by a mass spectrometric technique.
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D055598:Chemical Phenomena; D002621:Chemistry; D004546:Elapid Venoms / Q000032:analysis*; D007457:Iodine Radioisotopes; D007477:Ions; D013058:Mass Spectrometry / Q000295:instrumentation; D008970:Molecular Weight; D009498:Neurotoxins / Q000302:isolation & purification*
chemical_list: D000596:Amino Acids; D004546:Elapid Venoms; D007457:Iodine Radioisotopes; D007477:Ions; D009498:Neurotoxins