Changes in mitochondrial complex I activity and coenzyme Q binding site in Leber's hereditary optic neuropathy (LHON).

The complex I function in sub-mitochondrial particles was studied in platelets from patients and healthy carriers with 11778/ND4 or 3460/ND1 mtDNA point mutations associated with LHON. Both 11778/ND4 and 3460/ND1 mutations induced rotenone resistance and 11778/ND4 showed an increased K(m) for ubiquinol-2 with respect to the control group. It was concluded that even with different pathogenic mechanisms both mutations affect the quinone binding site of complex I.