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IntEnz - Home
IntEnz (Integrated relational Enzyme database) is a freely available resource
focused on enzyme nomenclature. IntEnz is created in collaboration with the
Swiss Institute of Bioinformatics (SIB).
This collaboration is responsible for the production of the
ENZYME resource.
IntEnz contains the recommendations of the Nomenclature Committee of the
International Union of Biochemistry and Molecular Biology
(NC-IUBMB) on the nomenclature and classification of enzyme-catalysed reactions.
All data in IntEnz is freely accessible and available for anyone to use.
Enzyme spotlight
EC 4.2.1.1
Carbonate dehydratase
Abstract:
Carbonate dehydratase, better known as carbonic anhydrase (CA), was first identified in 1932 by
Meldrum and Roughton in red blood cells, but it has since been found in organisms from all
kingdoms of life. In vivo, CA catalyses the hydration of
carbon dioxide
(CO2) and the dehydration of
hydrogencarbonate
(HCO3−):
CO2 + H2O
↔ HCO3− + H+
The inhibition of human CA is important in the treatment of glaucoma,
altitude sickness, and obesity, while its overexpression has recently been implicated in tumour
growth [1]. In phytoplankton, CA plays an essential part in the acquisition of inorganic carbon
for photosynthesis. CA is categorised into three main classes: α-CA (found in mammals,
plants,
eubacteria, and viruses), β-CA (plants, bacteria, and some animals) and γ-CA
(bacteria and plants), which
share no significant sequence similarity or overall structure, but which all contain a catalytic
zinc atom. Whereas α- and γ-CA use three histidine residues to coordinate zinc,
β-CA uses two cysteine residues and one histidine residue.
α-CA was one of the first proteins for which a crystal structure was obtained.
This is an enzyme that is particularly well suited to serve as a model in many types of
biophysical studies of protein–ligand binding [1].
Two new classes of CA have been discovered in marine diatoms: δ-CA, with an active site
similar to that of α-CA, and ζ-CA, which naturally uses cadmium as its catalytic
metal. The high-resolution crystal structures of cadmium carbonic anhydrase 1 (CDCA1) from the
model diatom species Thalassiosira weissflogii has been recently reported [2]. Although
CDCA1 is isolated as a native Cd enzyme, it can use either Zn or Cd for catalysis and
spontaneously exchanges the two metals.
References:
Krishnamurthy, V.M., Kaufman, G.K., Urbach,
A.R., Gitlin, I., Gudiksen, K.L., Weibel, D.B. and Whitesides, G.M. (2008)
Carbonic anhydrase as a model for biophysical
and physical-organic studies of proteins and protein–ligand binding.
Xu, Y., Feng, L., Jeffrey, P.D., Shi, Y. and
Morel, F.M.M. (2008)
Structure and metal exchange in the cadmium
carbonic anhydrase of marine diatoms.
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Acknowledgements
The project is supported by the European Commission under FELICS,
contract number 021902 (RII3) within the Research Infrastructure Action
of the FP6 "Structuring the European Research Area" Programme.
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