Ubiquinone - Biochemistry - Lecture Slides, Slides of Biochemistry

Download Ubiquinone - Biochemistry - Lecture Slides and more Slides Biochemistry in PDF only on Docsity! Ubiquinone (coenzyme Q, or Q) is a small hydrophobic, mobile, lipid-soluble benzoquinone electron carrier  Ubiquinone (Q, or coenzyme Q). Complete reduction of ubiquinone requires two electrons and two protons, and occurs in two steps through the semiquinone radical intermediate Docsity.com  Prosthetic groups of cytochromes. Each consists of four five- membered, nitrogen-containing rings in a cyclic structure called a porphyrin. The four nitrogen atoms are coordinated with a central Fe ion, either Fe2+ or Fe3+. Iron protoporphyrin IX is found in b-type cytochromes and in hemoglobin and myoglobin (see Fig. 6-17). Heme C is covalently bound to the protein of cytochrome c through thioether bonds to two Cys residues. Heme A, found in the a-type cytochromes, has a long isoprenoid tail attached to one of the five-membered rings. The conjugated double-bond system (shaded in red) of the porphyrin ring accounts for the absorption of visible light by these hemes. Docsity.com