From Wikipedia, the free encyclopedia
Mammalian protein found in Homo sapiens
In
enzymology , a phosphopantothenate—cysteine ligase also known as phosphopantothenoylcysteine synthetase (PPCS) is an
enzyme (
EC
6.3.2.5 ) that
catalyzes the
chemical reaction which constitutes the
second of five steps involved in the conversion of
pantothenate to
Coenzyme A . The reaction is:
NTP + (R)-4'-phosphopantothenate + L-cysteine
⇌
{\displaystyle \rightleftharpoons }
NMP + diphosphate + N-[(R)-4'-phosphopantothenoyl]-L-cysteine
The
nucleoside triphosphate (NTP) involved in the reaction varies from species to species. Phosphopantothenate—cysteine ligase from the bacterium
Escherichia coli uses
cytidine triphosphate (CTP) as an energy donor, whilst the human
isoform uses
adenosine triphosphate (ATP).
[1]
Nomenclature
This enzyme belongs to the family of
ligases , specifically those forming carbon-nitrogen bonds as acid-D-amino-acid ligases (peptide syntheses). The
systematic name of this enzyme class is (R)-4'-phosphopantothenate:L-cysteine ligase . This enzyme is also called phosphopantothenoylcysteine synthetase .
Gene
Phosphopantothenoylcysteine synthetase in humans is encoded by the PPCS
gene .
[6]
Protein structure
As of late 2007, 5
structures have been solved for this class of enzymes, with
PDB accession codes
1P9O ,
1U7U ,
1U7W ,
1U7Z , and
1U80 .
References
Further reading
External links
PDBe-KB provides an overview of all the structure information available in the PDB for Human Phosphopantothenate—cysteine ligase
6.1 : Carbon-Oxygen
6.2 : Carbon-Sulfur
6.3 : Carbon-Nitrogen
Activity Regulation Classification Kinetics Types