Adenosine triphosphate synthases

Topographs of membrane proteins at subnanometer resolution were first acquired on highly ordered 2D reconstituted systems, that is, OmpF, bacteriorhodopsin (BR), water channels, potassium channels, halorhodopsin, outer membrane (OM) porins, adenosine triphosphate synthase (ATPase) " and light-harvesting (LH) complexes. " Target proteins were initially isolated from biological membranes and then reconstituted into lipid bilayers to form regular arrays. However, as described before, there is a certain... 

The initial conversion of light into chemical energy takes place in the thylakoid membrane. Besides the chlorophylls and series of electron carriers, the thylakoid membrane also contains the enzyme adenosine triphosphate (ATP) synthase. The enzymes that are responsible for the actual fixation of C02 and the synthesis of carbohydrate reside in the stroma that surround the thylakoid membrane. The stroma also contains deoxyribonucleic acid (DNA), ribonucleic acid (RNA), and ribosomes that are essential for protein synthesis [37]. 

Fig. 14.1 Cellular pathway of methotrexate. ABCBl, ABCCl-4, ABC transporters ADA, adenosine deaminase ADP, adenosine diphosphate AICAR, aminoimidazole carboxamide ribonucleotide AMP, adenosine monophosphate ATIC, AICAR transformylase ATP, adenosine triphosphate SjlO-CH -THF, 5,10-methylene tetrahydrofolate 5-CHj-THF, 5-methyl tetrahydro-folate DHFR, dihydrofolate reductase dTMP, deoxythymidine monophosphate dUMP, deoxy-uridine monophosphate FAICAR, 10-formyl AICAR FH, dihydrofolate FPGS, folylpolyglutamyl synthase GGH, y-glutamyl hydrolase IMP, inosine monophosphate MTHFR, methylene tetrahydrofolate reductase MTR, methyl tetrahydrofolate reductase MTX-PG, methotrexate polyglutamate RFCl, reduced folate carrier 1 TYMS, thymidylate synthase. Italicized genes have been targets of pharmacogenetic analyses in studies published so far. (Reproduced from ref. 73 by permission of John Wiley and Sons Inc.)...

Boyer, Paul D. (1918- ). A chemist who won the Nobel Prize in 1997 for his work on elucidating the enzymatic mechanism by which ATP synthase (ATPase) catalyzes the synthesis of adenosine triphosphate (ATP), the energy source of living cells. He is a professor of biochemistry at the University of California, Los Angeles. He received a Ph.D. in Biochemistry in 1943 from the University of Wisconsin, Madison, U.S.A. 

E Schneider and K Altendorf (1987) Bacterial adenosine 5 -triphosphate synthase FiFq) purification and reconstitution of Fq complexes and biochemical and functional characerization of their subunits. Microbiol Rev 51 477-497... 

Oxidative phosphorylation The process by which adenosine triphosphate (ATP) is synthesized from a hydrogen ion gradient across the mitochondrial inner membrane. The hydrogen ion gradient is formed by the action of protein complexes in the mitochondrial membrane that sequentially transfer electrons from the rednced cofactors nicotinamide adenine dinucleotide (NADH) and FADH to molecnlar oxygen. Movement of hydrogen ions back into the mitochondrion via ATP synthase drives the synthesis of ATP. 

Fig. 7.2. The energy acquiring systems in the organisms (bacteria) which are supposed to have occurred at the earliest evolutionary stages. Hase, hydrogenase Cyt, cytochrome. ATP is probably biosynthesized by the catalysis of ATP synthase. ATP below downward arrow indicates that adenosine triphosphate is biosynthesized using the energy liberated from the reactions around this indicator...

The free energy gained from the quinol oxidation inthe cytochrome-6c, complex allows further proton transfer from the cytoplasm to the periplasm. The 6c,-complex also mediates ET to the periplasmic side. There, soluble cytochromes accept the electrons and transport them back to the RC to reduce D+. The electron transfer is cycUc and therefore does not cause transmembrane potential. This potential is generated by the electrogenic proton translocation in the cytochrome-6c, complex. The electrochemical proton gradient is utilized by the ATP-synthase to form adenosine triphosphate from adenosine diphosphate and phosphate. 

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