Susceptible Region of Myoglobins to In-source Decay Using Matrix-assisted Laser Desorption/Ionization Coupled with Delayed Extraction Reflectron Time-of-Flight Mass Spectrometer.

Abstract

The susceptibility to in-source decay (ISD) in myoglobin, using matrix-assisted laser desorption/ionization (MALDI) coupled with a delayed extraction reflectron time-of-flight (TOF) mass spectrometer, has been described from the standpoint of secondary structures. The ISD data of three different myoglobins showed a common intense product of c35 ion originated from the cleavage of amine bond N-C.ALPHA., at Gly35-His36 or Ser35-His36 residues. It is suggested that the relatively abundant formation of c35 ion in Gly35-His36 or Ser35-His36 residues is not due to the presence of His36 residue, but due to a turn region between helices in secondary structure of myoglobins.