AMBINEELA, AN UNUSUAL BLUE PROTEIN ISOLATED FROM THE ARCHAEON ACIDIANUS-AMBIVALENS

A novel blue protein, named ambineela, was isolated from the soluble e xtract of the thermoacidophilic archaeon Acidianus ambivalens. In solu tion, the purified protein is a monomer with 50 kDa and has a basic ch aracter (pI similar to 8.7). The electronic spectrum shows two bands, centred at 395 and 625 nm (A(625)/A(395) = 0.7). The protein does not contain any transition metal; its blue colour is due to an unidentifie d non-fluorescent cofactor, covalently bound to it. Ambineela N-termin al sequence exhibits a consensus ADP-binding region, suggesting that i ts unknown cofactor may comprise this molecule or an analogue. (C) 199 8 Academic Press.