catalyzes

(adjective)

Catalysis is the change in rate of a chemical reaction due to the participation of a substance called a catalyst. Unlike other reagents that participate in the chemical reaction, a catalyst is not consumed by the reaction itself.

Related Terms

Examples of catalyzes in the following topics:

  • Enzyme Catalysis

    • Once the reaction completes, the product(s) leaves the active site, so the enzyme is free to catalyze more reactions.
    • Enzymes can catalyze reactions through a variety of mechanisms.
    • An enzyme catalyzes a biochemical reaction by binding a substrate at the active site.
    • After the reaction has proceeded, the products are released and the enzyme can catalyze further reactions.
    • List the five typical mechanisms used by enzymes to catalyze biological reactions

  • The Aldol Reaction

    • Three examples of the base-catalyzed aldol reaction are shown in the first diagram below, and equivalent acid-catalyzed reactions also occur.
    • Stepwise mechanisms for the base-catalyzed and acid-catalyzed reactions are seen in the third and fourth diagrams below.
    • Acid-catalyzed conditions are more commonly used to effect this elimination (examples #1, 2 & 5), but base-catalyzed elimination also occurs, especially on heating (examples #3, 4 & 5).
    • Why then should the base-catalyzed elimination of water occur in aldol products?
    • Indeed, the base-catalyzed loss of hydroxide anion from the enol is a conjugated analog of the base-catalyzed decomposition of a hemiacetal.

  • Types and Functions of Proteins

    • Enzymes are proteins that catalyze biochemical reactions, which otherwise would not take place.
    • The substrates are the reactants that undergo the chemical reaction catalyzed by the enzyme.
    • These enzymes include amylase, which catalyzes the digestion carbohydrates in the mouth and small intestine; pepsin, which catalyzes the digestion of proteins in the stomach; lipase, which catalyzes reactions need to emulsify fats in the small intestine; and trypsin, which catalyzes the further digestion of proteins in the small intestine.
    • These biosynthetic enzymes include DNA Polymerase, which catalyzes the synthesis of new strands of the genetic material before cell division; fatty acid synthetase, which the synthesis of new fatty acids for fat or membrane lipid formation; and components of the ribosome, which catalyzes the formation of new polypeptides from amino acid monomers.

  • Enzymes Used in Industry

    • Enzymes are biological molecules that catalyze (increase the rates of) chemical reactions.
    • Enzymes are biological molecules that catalyze (increase the rates of) chemical reactions.
    • Most enzyme reaction rates are millions of times faster than those of comparable un-catalyzed reactions.
    • A few RNA molecules called ribozymes also catalyze reactions, with an important example being some parts of the ribosome.
    • In baking, they catalyze the breakdown of starch in the flour to sugar.

  • Organic Acid Metabolism

    • Degradation of formate is then catalyzed by formate dehydrogenase (FDH), which oxidizes formate to ultimately yield CO2.
    • This process requires the β-oxidation pathway, a cyclic process that catalyzes the sequential shortening of fatty acid acyl chains to the final product, acetyl-CoA.
    • Fatty acid chains are converted to enoyl-CoA (catalyzed by acyl-CoA dehydrogenase).

  • Enzyme Active Site and Substrate Specificity

    • Enzymes catalyze chemical reactions by lowering activation energy barriers and converting substrate molecules to products.
    • This dynamic binding maximizes the enzyme's ability to catalyze its reaction.
    • One of the important properties of enzymes is that they remain ultimately unchanged by the reactions they catalyze.
    • After an enzyme is done catalyzing a reaction, it releases its products (substrates).

  • The Energy-Releasing Steps of Glycolysis

    • In the seventh step, catalyzed by phosphoglycerate kinase (an enzyme named for the reverse reaction), 1,3-bisphosphoglycerate donates a high-energy phosphate to ADP, forming one molecule of ATP.
    • The enzyme catalyzing this step is a mutase (isomerase).
    • Enolase catalyzes the ninth step.
    • The last step in glycolysis is catalyzed by the enzyme pyruvate kinase (the enzyme in this case is named for the reverse reaction of pyruvate's conversion into PEP) and results in the production of a second ATP molecule by substrate-level phosphorylation and the compound pyruvic acid (or its salt form, pyruvate).
    • Many enzymes in enzymatic pathways are named for the reverse reactions since the enzyme can catalyze both forward and reverse reactions (these may have been described initially by the reverse reaction that takes place in vitro, under non-physiological conditions).

  • Weak Bases

    • Weak bases can also be used to catalyze certain reactions, such as enolate formation, as demonstrated in the figure below:
    • A weak base, symbolized by B:, can catalyze enolate formation by acting as a proton acceptor.

  • Three-Membered Rings

    • The acid-catalyzed additions in examples 2 and 3, illustrate the influence of substituents on the regioselectivity of addition.
    • As illustrated below, acid and base-catalyzed reactions normally proceed by 5-exo-substitution (reaction 1), yielding a tetrahydrofuran product.
    • However, if the oxirane has an unsaturated substituent (vinyl or phenyl), the acid-catalyzed opening occurs at the allylic (or benzylic) carbon (reaction 2) in a 6-endo fashion.

  • Oxidoreductase Protein Complexes

    • In biochemistry, an oxidoreductase is an enzyme that catalyzes the transfer of electrons from one molecule to another.
    • In biochemistry, an oxidoreductase is an enzyme that catalyzes the transfer of electrons from one molecule, the reductant, also called the electron donor, to another the oxidant, also called the electron acceptor.
    • For example, an enzyme that catalyzed this reaction would be an oxidoreductase: A– + B → A + B–.