Specification of the inhibitory action of MIBG on the respiratory chain by EPR scanning
Cornelissen, J.; Van Belzen, R.; Van Gennip, A.H.; Voûte, P.A.; Van Kuilenburg, A.B.
Anticancer Research 17(1a): 265-268
1997
ISSN/ISBN: 0250-7005 PMID: 9066663 Document Number: 471261
In this paper we report EPR studies on the effects of meta-Iodobenzylguanidine (MIBG), a structural analogue of norepinephrine capable of inhibiting complex I and III of the respiratory chain, on the reduction state of the various complexes of the respiratory chain in beef heart submitochondrial particles. The EPR spectrum of SMPs incubated with MIBG showed completely reduced prosthetic groups of complex I, but oxidised prosthetic groups of complex IV. This indicates that complex I is inhibited by MIBG at the end of the complex (i.e. at the Q binding site). Determination of the exact site of inhibition of MIBG on complex III yielded no conclusive results, but did confirm that complex III is indeed inhibited by MIBG.