Arginase family proteins are ureohydrolases with important roles in
arginine/agmatine metabolism, the urea cycle, histidine degradation, and other
pathways. The family includes arginase and evolutionary related  enzymes of
about 300 amino acids that typically contain two manganese ions in the active
Some proteins that belong to the arginase family are listed below:
Arginase (EC 126.96.36.199), a ubiquitous enzyme which catalyzes the degradation
of arginine to ornithine and urea . Two isoenzymes are found in mammals.
Arginase-1 catalyzes the final cytosolic step of the urea cycle in liver,
but it is also found in non-hepatic tissues. Arginase-2 is a mitochondrial
enzyme that functions in arginine homeostasis in nonhepatic tissues.
Deficiency of arginase can lead to diseases related to the accumulation of
arginine or ammonia.
Agmatinase (EC 188.8.131.52) (agmatine ureohydrolase), a prokaryotic enzyme
(gene speB) that catalyzes the hydrolysis of agmatine into putrescine and
Formiminoglutamase (EC 184.108.40.206) (formiminoglutamate hydrolase), a
prokaryotic enzyme (gene hutG) that hydrolyzes N-formimino-glutamate into
glutamate and formamide.
Proclavaminate amidinohydrolase (EC 220.127.116.11) from Streptomyces
clavuligerus (gene pah), an enzyme involved in antibiotic clavulanic acid
Guanidinobutyrase (EC 18.104.22.168) from Arthrobacter sp. (gene gbh), an enzyme
that hydrolyzes guanidinobutanoate into aminobutanoate and urea and that
requires one zinc ion instead of manganese.
Hypothetical proteins from methanogenic archaebacteria.
Known 3-D structures of such enzymes show trimeric or hexameric structures
[3,4,5,6]. Each monomer forms a conserved α/β fold with a central parallel
β-sheet flanked on both sides by several α-helices (see <PDB:1RLA; B>).
Three conserved regions that contain charged residues which are involved in
the binding of the two manganese ions in the active site are located in loop
segments of the central β-sheet [3,4,5,6]. We have used one of these regions
for a signature pattern and we have also developed a profile that covers the
entire arginase structure.
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