synthase

(noun)

Any enzyme that catalyzes the synthesis of a biological compound but, unlike synthetases, does not make use of ATP as a source of energy

Related Terms

Examples of synthase in the following topics:

  • F10 ATP Synthase

    • The overall reaction sequence is: ATP synthase + ADP + Pi → ATP Synthase + ATP
    • Located within the mitochondria, ATP synthase consists of 2 regions: the FO portion is within the membrane and the F1 portion of the ATP synthase is above the membrane, inside the matrix of the mitochondria .
    • Oligomycin, an antibiotic, is able to inhibit the FO unit of ATP synthase.
    • E. coli ATP synthase is the simplest known form of ATP synthase, with 8 different subunit types.
    • Discuss the structure and function of ATP synthase, including the F1 and FO components

  • Chemiosmosis and Oxidative Phosphorylation

    • Similarly, hydrogen ions in the matrix space can only pass through the inner mitochondrial membrane through a membrane protein called ATP synthase.
    • In oxidative phosphorylation, the hydrogen ion gradient formed by the electron transport chain is used by ATP synthase to form ATP.
    • ATP synthase is a complex, molecular machine that uses a proton (H+) gradient to form ATP from ADP and inorganic phosphate (Pi).

  • Processes of the Light-Dependent Reactions

    • Cytochrome b6f complex and ATP synthase are also major protein complexes in the thylakoid membrane that work with the photosystems to create ATP and NADPH.
    • Cytochrome b6f and ATP synthase work together to create ATP.
    • The energy released by the hydrogen ion stream allows ATP synthase to attach a third phosphate group to ADP, which forms ATP .
    • This flow of hydrogen ions through ATP synthase is called chemiosmosis because the ions move from an area of high to an area of low concentration through a semi-permeable structure.
    • ATP synthase uses this electrochemical gradient to make ATP.

  • Purine and Pyrimidine Synthesis

    • UDP can also be converted to CTP by CTP synthase cytidine 5'triphosphate (CTP)using glutamine and ATP.The first three enzymes are all coded by the same gene in Metazoa (CAD).
    • CTP synthase (or CTP synthetase) is an enzyme involved in pyrimidine biosynthesis.
    • CTP synthase is activated by GTP, a purine.
    • CTP synthase is inhibited by reversible by CTP and irreversible for example by the glutamine analogon DON.
    • The following human genes encode proteins that possess CTP synthase activity:

  • Polyketide Antibiotics

    • The polyketide chains produced by a minimal polyketide synthase are often further derivitized and modified into bioactive natural products.
    • Polyketides are synthesized by one or more specialized and highly complex polyketide synthase (PKS) enzymes.

  • Respiration and Proton Motive Force

    • They are able to do this with the help of the solar-driven enzyme bacteriorhodopsin, which is used to drive the molecular motor enzyme ATP synthase to make the necessary conformational changes required to synthesize ATP.
    • By running ATP synthase in reverse, proton gradients are also made by bacteria and are used to drive flagella.
    • The F1FO ATP synthase is a reversible enzyme.
    • In respiring bacteria under physiological conditions, ATP synthase, in general, runs in the opposite direction.

  • Proton Reduction

    • In respiring bacteria under physiological conditions, ATP synthase, in general, runs in the opposite direction, creating ATP while using the proton motive force created by the electron transport chain as a source of energy.
    • The same process takes place in the mitochondria, where ATP synthase is located in the inner mitochondrial membrane, so that F1 part sticks into the mitochondrial matrix where ATP synthesis takes place.
    • A proton motive force or pmf drives protons down the gradient (across the membrane) through the proton channel of ATP synthase.

  • The Acetyl-CoA Pathway

    • The two major enzymes involved in these processes are carbon monoxide dehydrogenase and acetyl CoA synthase complex.
    • The acetyl-CoA synthase complex is responsible for this reaction.
    • The carbon monoxide dehydrogenase allows organisms to use carbon dioxide as a source of carbon and carbon monoxide as a source of energy.The carbon monoxide dehydrogenase can also form a complex with the acetyl-CoA synthase complex which is key in the acetyl-CoA pathway.

  • Citric Acid and Other Organic Compounds

    • It is produced from acetyl coenzyme A and oxaloacetate in the presence of the enzyme citrate synthase.

  • Secondary Active Transport

    • The potential energy that accumulates in the stored hydrogen ions is translated into kinetic energy as the ions surge through the channel protein ATP synthase, and that energy is used to convert ADP into ATP.