title: Estimation of proton affinity of proline and tryptophan under electrospray ionization conditions using the extended kinetic method.
abstract: The relative order of the proton affinity (PA) of 20 naturally occurring amino acids has been determined under electrospray ionization conditions and compared with earlier studies of different research workers. The order we obtained is similar to that reported by other groups except in three cases viz., valine--aspartic acid, asparagine--glutamic acid and tryptophan--proline. The PA values of proline and tryptophan are determined by the extended kinetic method using amino acids themselves as reference bases. The PA values we thus obtained for proline and tryptophan are 219.9 and 221.6 kcal/mol, respectively.
authors.affiliation: National Centre for Mass Spectrometry, Indian Institute of Chemical Technology, Hyderabad - 500 007, India.
authors.forename: S P
authors.initials: SP
authors.lastname: Mirza
authors.forename: S
authors.initials: S
authors.lastname: Prabhakar
authors.forename: M
authors.initials: M
authors.lastname: Vairamani
mesh_terms: D011392:Proline / Q000032:analysis / Q000737:chemistry*; D011522:Protons; D015203:Reproducibility of Results; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D013816:Thermodynamics; D014364:Tryptophan / Q000032:analysis / Q000737:chemistry*
chemical_list: D011522:Protons; D014364:Tryptophan; D011392:Proline