Chemi- and bioluminescence of coelenterazine analogues possessing an adamantylmethyl group

Coelenterazine analogues possessing the adamantylmethyl group at the C2 or C8 position were prepared to study their effects on chemi-and bioluminescence. Stability of the excited state coelenteramide analogues was significantly affected by the substitutions, resulting in a neutral amide emission of chemiluminescence in diglyme-acetate buffer and in a blue-shifted emission of bioluminescence in Tris-HCl buffer. Substitution of the adamantylmethyl group in the C8 position caused bioluminescence intensity to double. The 8-adamantylmethyl group may serve to orient the coelenterazine skeleton in a suitable position in the active site for efficient bioluminescence activity. Results with semi-synthetic AQs containing 8-adamantylmethyl analogues, and those of semi-synthetic AQs containing 2-benzyl and 2-methyl analogues, indicate that apoAQ and apoAQ C145,152,180S have the ability to recognize the C2 and C8 side-chains in coelenterazine during AQ regeneration. (C) 1997 Elsevier Science Ltd.