Malate dehydrogenase (decarboxylating) () or NAD-malic enzyme (NAD-ME) is an enzyme that
catalyzes
Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recyc ...
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 ...
:(S)-malate + NAD
+ pyruvate + CO
2 + NADH
Thus, the two
substrates of this enzyme are
(S)-malate and
NAD+, whereas its three
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
pyruvate
Pyruvic acid (CH3COCOOH) is the simplest of the alpha-keto acids, with a carboxylic acid and a ketone functional group. Pyruvate, the conjugate base, CH3COCOO−, is an intermediate in several metabolic pathways throughout the cell.
Pyruvic aci ...
,
CO2, and
NADH
Nicotinamide adenine dinucleotide (NAD) is a coenzyme central to metabolism. Found in all living cells, NAD is called a dinucleotide because it consists of two nucleotides joined through their phosphate groups. One nucleotide contains an aden ...
. Malate is
oxidized
Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a d ...
to pyruvate and CO
2, and NAD
+ is reduced to NADH.
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, to be specific, 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 (S)-malate:NAD
+ oxidoreductase (decarboxylating). This enzyme participates in
pyruvate metabolism
Pyruvic acid (CH3COCOOH) is the simplest of the alpha-keto acids, with a carboxylic acid and a ketone functional group. Pyruvate, the conjugate base
A conjugate acid, within the Brønsted–Lowry acid–base theory, is a chemical compoun ...
and
carbon fixation
Biological carbon fixation or сarbon assimilation is the process by which inorganic carbon (particularly in the form of carbon dioxide) is converted to organic compounds by living organisms. The compounds are then used to store energy and as ...
. NAD-malic enzyme is one of three decarboxylation enzymes used in the inorganic carbon concentrating mechanisms of
C4 and
CAM
Calmodulin (CaM) (an abbreviation for calcium-modulated protein) is a multifunctional intermediate calcium-binding messenger protein expressed in all eukaryotic cells. It is an intracellular target of the secondary messenger Ca2+, and the bind ...
plants. The others are
NADP-malic enzyme
Malate dehydrogenase (oxaloacetate-decarboxylating) (NADP+) () or NADP-malic enzyme (NADP-ME) is an enzyme that catalyzes the chemical reaction in the presence of a bivalent metal ion:
:(S)-malate + NADP+ \rightleftharpoons pyruvate + CO2 + NADP ...
and
PEP carboxykinase
Phosphoenolpyruvate carboxykinase (, PEPCK) is an enzyme in the lyase family used in the metabolic pathway of gluconeogenesis. It converts oxaloacetate into phosphoenolpyruvate and carbon dioxide.
It is found in two forms, cytosolic and mitoch ...
.
[
][
]
References
*
EC 1.1.1
NADH-dependent enzymes
{{1.1.1-enzyme-stub