The

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 ...

threonine aldolase () is an

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 ...

:L-threonine

\rightleftharpoons

glycine + acetaldehyde This enzyme belongs to the family of

lyase In biochemistry, a lyase is an enzyme that catalyzes the breaking (an elimination reaction) of various chemical bonds by means other than hydrolysis (a substitution reaction) and oxidation, often forming a new double bond or a new ring structure. ...

s, specifically the aldehyde-lyases, which cleave carbon-carbon bonds. 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 L-threonine acetaldehyde-lyase (glycine-forming). This enzyme is also called L-threonine acetaldehyde-lyase. This enzyme participates in glycine,

serine Serine (symbol Ser or S) is an α-amino acid that is used in the biosynthesis of proteins. It contains an α-amino group (which is in the protonated − form under biological conditions), a carboxyl group (which is in the deprotonated − form un ...

and threonine

metabolism Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run cell ...

. It employs one cofactor,

pyridoxal phosphate Pyridoxal phosphate (PLP, pyridoxal 5'-phosphate, P5P), the active form of vitamin B6, is a coenzyme in a variety of enzymatic reactions. The International Union of Biochemistry and Molecular Biology has catalogued more than 140 PLP-dependent ac ...

Structural studies

As of late 2007, 5

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 .

Presence in human and mouse

The enzyme is synthesized and functional in mice.Alasdair J Edgar (2005)
Mice have a transcribed L-threonine aldolase/GLY1 gene, but the human GLY1 gene is a non-processed pseudogene. BMC Genomics March 2005, 6:32
pdf
/ref> Humans also have the remnants of the gene, coding this enzyme (GLY1), however it is damaged by past mutations and inactive. Human gene contains two single nucleotide deletions causing frameshifts and premature stop codons. Also, the encoded protein would not be active anyway due mutations in other highly conserved regions. Human gene is no longer transcribed into RNA.

References

* * * EC 4.1.2 Pyridoxal phosphate enzymes Enzymes of known structure Pseudogenes {{4.1-enzyme-stub