Dicyclohexylcarbodiimide inhibits proton pumping in ubiquinol:cytochrome c oxidoreductase of Rhodobacter sphaeroides and binds to aspartate-187 of cytochrome b. 1998

Y Wang, and V Obungu, and D S Beattie
Department of Biochemistry, West Virginia University School of Medicine, Morgantown 26505-9142, USA.

In recent studies we reported that dicyclohexylcarbodiimide (DCCD) inhibited proton translocation in ubiquinol:cytochrome c oxidoreductase (cytochrome bc1 complex) from yeast mitochondria where it was bound to aspartate-160 of cytochrome b. In the current study, we report that DCCD and its fluorescent analogue, N-cyclohexyl-N'-[4-(dimethylamino)naphthyl]-carbodiimide (NCD-4), inhibit 50-60% proton pumping in the cytochrome bc1 complex of the bacterium Rhodobacter sphaeroides with a 20% inhibition of electron transfer activity. Radioactive DCCD is bound exclusively to cytochrome b at aspartate-187, which is located at the C-terminal region of the CD loop connecting membrane-spanning helices C and D of cytochrome b. Fluorescent studies with NCD-4 revealed that aspartate-187 is located in a mildly hydrophobic pocket in the bc1 complex at a distance of 2-3 A from the surface of the membrane.

UI MeSH Term Description Entries
D011485 Protein Binding The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments. Plasma Protein Binding Capacity,Binding, Protein
D011522 Protons Stable elementary particles having the smallest known positive charge, found in the nuclei of all elements. The proton mass is less than that of a neutron. A proton is the nucleus of the light hydrogen atom, i.e., the hydrogen ion. Hydrogen Ions,Hydrogen Ion,Ion, Hydrogen,Ions, Hydrogen,Proton
D002234 Carbodiimides Compounds with the general formula RN Carbodiimide
D003573 Cytochrome b Group Cytochromes (electron-transporting proteins) with protoheme (HEME B) as the prosthetic group. Cytochromes Type b,Cytochromes, Heme b,Group, Cytochrome b,Heme b Cytochromes,Type b, Cytochromes,b Cytochromes, Heme,b Group, Cytochrome
D004024 Dicyclohexylcarbodiimide A carbodiimide that is used as a chemical intermediate and coupling agent in peptide synthesis. (From Hawley's Condensed Chemical Dictionary, 12th ed) DCCD
D004579 Electron Transport The process by which ELECTRONS are transported from a reduced substrate to molecular OXYGEN. (From Bennington, Saunders Dictionary and Encyclopedia of Laboratory Medicine and Technology, 1984, p270) Respiratory Chain,Chain, Respiratory,Chains, Respiratory,Respiratory Chains,Transport, Electron
D005456 Fluorescent Dyes Chemicals that emit light after excitation by light. The wave length of the emitted light is usually longer than that of the incident light. Fluorochromes are substances that cause fluorescence in other substances, i.e., dyes used to mark or label other compounds with fluorescent tags. Flourescent Agent,Fluorescent Dye,Fluorescent Probe,Fluorescent Probes,Fluorochrome,Fluorochromes,Fluorogenic Substrates,Fluorescence Agents,Fluorescent Agents,Fluorogenic Substrate,Agents, Fluorescence,Agents, Fluorescent,Dyes, Fluorescent,Probes, Fluorescent,Substrates, Fluorogenic
D001426 Bacterial Proteins Proteins found in any species of bacterium. Bacterial Gene Products,Bacterial Gene Proteins,Gene Products, Bacterial,Bacterial Gene Product,Bacterial Gene Protein,Bacterial Protein,Gene Product, Bacterial,Gene Protein, Bacterial,Gene Proteins, Bacterial,Protein, Bacterial,Proteins, Bacterial
D012242 Rhodobacter sphaeroides Spherical phototrophic bacteria found in mud and stagnant water exposed to light. Rhodopseudomonas sphaeroides,Rhodobacter spheroides,Rhodopseudomonas spheroides
D013050 Spectrometry, Fluorescence Measurement of the intensity and quality of fluorescence. Fluorescence Spectrophotometry,Fluorescence Spectroscopy,Spectrofluorometry,Fluorescence Spectrometry,Spectrophotometry, Fluorescence,Spectroscopy, Fluorescence

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