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 3-methyl-2-oxobutanoate dehydrogenase () 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 ...

:3-methyl-2-oxobutanoate + ihydrolipoyllysine-residue (2-methylpropanoyl)transferaselipoyllysine

\rightleftharpoons

ihydrolipoyllysine-residue (2-methylpropanoyl)transferaseS-(2-methylpropanoyl)dihydrolipoyllysine + CO₂ The 3 substrates of this enzyme are 3-methyl-2-oxobutanoate,

dihydrolipoyllysine-residue (2-methylpropanoyl)transferase In enzymology, a dihydrolipoyllysine-residue (2-methylpropanoyl)transferase () is an enzyme that catalyzes the chemical reaction :2-methylpropanoyl-CoA + enzyme N6-(dihydrolipoyl)lysine \rightleftharpoons CoA + enzyme N6-(S- -methylpropanoylihyd ...

, and lipoyllysine, 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-methylpropanoyl)dihydrolipoyllysine, and CO₂. 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 aldehyde or oxo group of donor with a disulfide as acceptor. This enzyme participates in

valine, leucine and isoleucine degradation A branched-chain amino acid (BCAA) is an amino acid having an aliphatic side-chain with a branch (a central carbon atom bound to three or more carbon atoms). Among the proteinogenic amino acids, there are three BCAAs: leucine, isoleucine, and va ...

. It employs one cofactor,

thiamin diphosphate Thiamine pyrophosphate (TPP or ThPP), or thiamine diphosphate (ThDP), or cocarboxylase is a thiamine (vitamin B1) derivative which is produced by the enzyme thiamine diphosphokinase. Thiamine pyrophosphate is a cofactor that is present in all liv ...

. It is the E1 subunit of a catalytic complex.

Structural studies

As of late 2007, twenty-nine

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 1.2.4 Thiamine enzymes Enzymes of known structure {{1.2-enzyme-stub