Amidases

Amidases
Enzyme classification
EC, category	3.5.-.- ,  hydrolase
Response type	hydrolytic cleavage
Substrate	Amides

Amidases (also: amidohydrolases ) are in Enzymology , a branch of Biochemistry , enzymes which a chemical reaction for the cleavage of amide bonds catalyze . The enzymes form a subfamily of hydrolases . They fulfill important functions in all living things.

Catalyzed reactions

A monocarboxylic acid amide reacts with water under the influence of an amidase to form a monocarboxylic acid and ammonia or the ammonium salt of the monocarboxylic acid:

${\displaystyle \mathrm {R{\text{-}}CO{\text{-}}NH_{2}+H_{2}O\longrightarrow \;R{\text{-}}CO{\text{-}}OH+NH_{3}\;\;\rightleftharpoons \;\;R{\text{-}}COO^{-}+NH_{4}^{+}} }$

Some secondary amides are also hydrolyzed by amidases, but this shows the stability of most of the amide bonds, which cannot be split in this way:

${\displaystyle \mathrm {R{\text{-}}CO{\text{-}}NH{\text{-}}R'+H_{2}O\longrightarrow \;R{\text{-}}CO{\text{-}}OH+R'{\text{-}}NH_{2}} }$

Secondary amide is converted into carboxylic acid and amine

In the special case of a peptide bond , the cleaving enzymes are called peptidases ; formally, these no longer belong to the amidases, but represent the enzyme category 3.4.

Cyclic amide bonds, for example in lactams , are cleaved by lactamases , which also belong to the amidases:

Opening of the lactam ring in penicillin by a beta-lactamase and subsequent spontaneous splitting off of CO ₂

Amidases in humans

Several dozen amidases have been identified in humans, all of which serve important functions, including ceramidases , histone deacetylases, and sirtuins . Other important individual enzymes in this group are arylformamidase , biotinidase , glutaminase and pantetheinase .

pathology

Polymorphisms are known of eight amidases in humans , which can lead to rare hereditary diseases .

Gene name	Amidase	OMIM	Hereditary disease
ACY1	Aminoacylase-1	609924	Encephalopathy with Associated Aminoacylase-1 Deficiency (ACY1D)
AGA	Glycosyl asparaginase	208400	Aspartyl glucosaminuria (AGU)
ASAH1	Acid ceramidase	228000	Farber Syndrome
ASPA	Asparto acylase	271900	Canavan syndrome
BTD	Biotinidase	253260	Biotinidase deficiency
HDAC4	Histone deacetylase 4	600430	Brachydactyly with Associated Intellectual Disability (BDMR), also known as 2q37 microdeletion syndrome
PIGL	N-acetylglucosaminyl-N-deacetylase	280000	CHIME syndrome
UPB1	Beta ureidopropionase	613161	Beta Ureidopropionase Deficiency (BUPD)

Technical application for the resolution of racemates

The enzyme L- acylase is also one of the amidases. It is used industrially in the resolution of amino acids . The acetylation of the amino group of the racemic amino acid DL - methionine with acetic anhydride results in N -acetyl- DL- methionine ( RS ) - 1 , a 1: 1 mixture of ( S ) - 1 and ( R ) - 1 . The acetyl group of the N -acetyl- L- methionine ( S ) - 1 is then split off enantiospecifically under the catalytic influence of the L -acylase , resulting in L- methionine ( S ) - 2 and acetic acid . The N -acetyl- D -methionine ( R ) - 1 remains unchanged:

This process is also called kinetic resolution. Many other α-aminocarboxylic acids can be resolved using the same separation principle.

literature

• InterPro: amidase
• Lexicon of Biochemistry , Spectrum Academic Publishing House
• K. Drauz, H. Gröger , O. May (Ed.): Enzyme Catalysis in Organic Synthesis, Volume 1 . Wiley, 2012 ( full text in Google Book Search).

Individual evidence

1. ^ Albert Gossauer: Structure and reactivity of biomolecules , Verlag Helvetica Chimica Acta, Zurich, 2006, p. 450, ISBN 978-3-906390-29-1 .
2. ↑ OrphaNet: ACY1D
3. ↑ OrphaNet: AGU
4. ↑ OrphaNet: Canavan-S.
5. ↑ OrphaNet: 2q37
6. ↑ OrphaNet: BUPD
7. ↑ Chibata I, Tosa T: Use of immobilized cells . In: Annu. Rev. Biophys. Bioeng. . 10, 1981, pp. 197-216. doi : 10.1146 / annurev.bb.10.060181.001213 . PMID 7020575 .