[The globule diameter and various electron and conformational properties of the flavoprotein fragment of mitochondrial NADH dehydrogenase studied by fluorescence spectroscopy].
The globule dimensions and some electron and conformational properties of the flavoprotein (peripheral) fragment of the mitochondrial NADH dehydrogenase were determined by the time-resolved, phase-modulating, and polarization fluorescence spectroscopies, as well as correlated confocal microscopy. The rotational and the diffusion (translocation) diameters of the protein fragment were shown to be no less than 44 A and approximately 72 A, respectively. The diameter of protomitochondrial particles from the bovine heart, which were used for the isolation of the fraction of peripheral fragments, was no less than 2300 A. The fluorescence from tryptophan and flavin fluorophores in the fragment is strongly quenched by iron of the iron-sulfur clusters, which suggests that a strong electron-vibrational interaction of iron with Trp residues and flavin takes place. An overlapping of the electron clouds of iron-sulfur clusters, Trp residues, and flavin is likely to facilitate the electron transfer through the protein. The heat inactivation of the enzyme was accompanied by neither its substantial conformational changes, nor a considerable release of iron ions from the clusters located near the Trp residues.
Sukharev
V I
VI
Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Moscow Oblast, 142290 Russia.
Vekshin
N L
NL
D000818:Animals; D002417:Cattle; D005420:Flavoproteins / Q000737:chemistry*; D008297:Male; D008929:Mitochondria, Heart / Q000737:chemistry*; D009245:NADH Dehydrogenase / Q000737:chemistry*; D011487:Protein Conformation; D017510:Protein Folding; D013050:Spectrometry, Fluorescence / Q000379:methods; D014364:Tryptophan / Q000737:chemistry
D005420:Flavoproteins; D014364:Tryptophan; D009245:NADH Dehydrogenase
Diametr globuly i nekotorye élektronno-konformatsionnye svoĭstva flavoproteinovogo fragmenta mitokhondrial'noĭ NADH-degidrogenazy po dannym fluorestsentnoĭ spektroskopii.