Resonant energy transfer from proteins to pyridine nucleotides in mitochondria.

Resonant energy transfer in mitochondria from tryptophan residues of proteins to NAD(P)H has been proved. Only one tryptophan residue is a donor per NAD(P)H acceptor molecule. Increasing fluorescence intensity of mitochondrial proteins, observed in hypotonic solution or upon addition of calcium ions, is due to elimination of the energy transfer because of the oxidation of NAD(P)H to NAD(P)+.