enzymology Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. A ...

, a ketol-acid reductoisomerase () is an

enzyme Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. A ...

that catalyzes the

chemical reaction A chemical reaction is a process that leads to the IUPAC nomenclature for organic transformations, chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the pos ...

:(R)-2,3-dihydroxy-3-methylbutanoate + NADP⁺

\rightleftharpoons

(S)-2-hydroxy-2-methyl-3-oxobutanoate + NADPH + H⁺ Thus, the two substrates of this enzyme are (R)-2,3-dihydroxy-3-methylbutanoate and NADP⁺, whereas its 3

products Product may refer to: Business * Product (business), an item that serves as a solution to a specific consumer problem. * Product (project management), a deliverable or set of deliverables that contribute to a business solution Mathematics * Produ ...

are (S)-2-hydroxy-2-methyl-3-oxobutanoate,

NADPH Nicotinamide adenine dinucleotide phosphate, abbreviated NADP or, in older notation, TPN (triphosphopyridine nucleotide), is a cofactor used in anabolic reactions, such as the Calvin cycle and lipid and nucleic acid syntheses, which require NAD ...

, and H⁺. This enzyme belongs to the family of

oxidoreductase 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. This group of enzymes usually ut ...

s, specifically those acting on the CH-OH group of donor with NAD⁺ or NADP⁺ as acceptor. The

systematic name A systematic name is a name given in a systematic way to one unique group, organism, object or chemical substance, out of a specific population or collection. Systematic names are usually part of a nomenclature. A semisystematic name or semitrivial ...

of this enzyme class is (R)-2,3-dihydroxy-3-methylbutanoate:NADP⁺ oxidoreductase (isomerizing). Other names in common use include dihydroxyisovalerate dehydrogenase (isomerizing), acetohydroxy acid isomeroreductase, ketol acid reductoisomerase, alpha-keto-beta-hydroxylacyl reductoisomerase, 2-hydroxy-3-keto acid reductoisomerase, acetohydroxy acid reductoisomerase, acetolactate reductoisomerase, dihydroxyisovalerate (isomerizing) dehydrogenase, isomeroreductase, and reductoisomerase. This enzyme participates in valine, leucine and isoleucine biosynthesis and

pantothenate and coa biosynthesis Pantothenic acid, also called vitamin B5 is a water-soluble B vitamin and therefore an essential nutrient. All animals require pantothenic acid in order to synthesize coenzyme A (CoA) – essential for fatty acid metabolism – as well as to, ...

Structural studies

As of late 2007, 4

structures A structure is an arrangement and organization of interrelated elements in a material object or system, or the object or system so organized. Material structures include man-made objects such as buildings and machines and natural objects such as ...

have been solved for this class of enzymes, with PDB accession codes , , , and .

References

* * * * EC 1.1.1 NADPH-dependent enzymes Enzymes of known structure {{1.1.1-enzyme-stub