Observation of large, non-covalent globin subassemblies in the similar to 3600 kDa hexagonal bilayer hemoglobins by electrospray ionization time-of-flight mass spectrometry

A non-covalent globin subassembly comprising 12 globin chains (204 to 214 k Da) was observed directly by electrospray ionization time-of-flight mass sp ectrometry in the native hexagonal bilayer hemoglobins from the oligochaete s Lumbricus terrestris and Tubifex tubifex, the polychaetes Tylor-rhynchus heterochaetus, Arenicola marina, Amphitrite ornata and Alvinella pompejana, the leeches Macrobdella decora, Haemopis grandis and Nephelopsis oscura an d the chlorocruorin from the polychaete Myxicola infundibulum, over the pH range 3.5-7.0. The Hb from the deep-sea polychaete Alvinella exhibited in a ddition, peaks at similar to 107 kDa and at similar to 285 kDa, which were assigned to subassemblies of six globin chains and of 12 globin chains with three non-globin Linker chains, respectively. The experimental masses decr eased slightly with increased de-clustering potential (60 to 160 V) and wer e generally 0.1 to 0.2 % higher than the calculated masses, due probably to complexation with cations and water molecules. (C) 2001 Academic Press.