Endo T, Oya M, Kaptein R, Vuister G W, Kihara H, Mohri N, Tanaka S, Ohno M
Department of Chemistry, College of Technology, Gunma University, Kiryu, Japan.
FEBS Lett. 1988 Mar 28;230(1-2):57-60. doi: 10.1016/0014-5793(88)80641-0.
Proton NMR spectra of a dimeric phospholipase A2 from Trimeresurus flavoviridis have been recorded. N-1 proton resonances of the tryptophan indole rings have been detected and assigned to specific positions, Trp-3/Trp-30, Trp-68 and Trp-108, by comparing the spectra of the enzyme derivatives with tryptophans oxidized to differing extents. Photo-CIDNP experiments have revealed that Trp-68 and Trp-108 are exposed while Trp-3 and Trp-30 are buried in the molecule. This is consistent with the X-ray crystal structure of a homologous phospholipase A2 from Crotalus atrox where residues 3 and 30 are located at a dimer interface, but inconsistent with the results of stepwise oxidation of tryptophan residues.
