SYNTHESIS OF A PH-SENSITIVE SPIN-LABELED CYCLOHEXYLCARBODIIMIDE DERIVATIVE FOR PROBING PROTONATION REACTIONS IN PROTON-PUMPING ENZYMES

摘要

The synthesis of a pH-sensitive spin-labeled carbodiimide, N-cyclohexyl-N'-(1-oxyl-2,2,3,5,5-pentamethylimidazolidine-4-yl)-methylcar bodiimide (1) described. The compound is an analog of dicyclohexylcarbodiimide and reacts specifically with the membrane sector of the proton-pumping F1F0-type ATP synthase. This reaction of 1 with the ATP synthase (and perhaps other proton-pumping enzymes) should enable studies of protonation reactions in the enzyme using ESR spectroscopy. The preparation of another potentially useful pH-sensitive spin-label, 4-isothiocyanatomethyl-2,2,3,5,5-pentamethylimidazolidine-1-oxyl (8) is also described. (C) 1996 Elsevier Science Ltd. [References: 31]