Amidohydrolases urease

Amidohydrolases urease, amidase, carbamoylase, phosphotriesterase, chlorohydrolase Holm, 1997... 

Arginine + H2O citrulline + urea Urea amidohydrolase (urease) (E.C. 3.5.1.5)... 

A wide variety of aerobic and anaerobic microorganisms are able to express the enzyme urease (urea amidohydrolase), which catalyses the hydrolysis of urea to ammonia and carbon dioxide.27 So far,... 

The first enzyme that was demonstrated to contain nickel was urease (urea amidohydrolase) from jack bean. It catalyzes the hydrolysis of urea to ammonia and carbon dioxide. The protein has a multimeric structure with a relative molecular mass of 590,000 Da. Analysis indicated 12 nickel atoms/mol. Binding studies with the inhibitors indicated an equivalent weight per active site of 105,000, corresponding to 2 nickel atoms/active site. During removal of the metal by treatment with EDTA at pH 3.7, the optical absorption and enzymatic activity correlated with nickel content. This, combined with the sensitivity of the enzyme to the chelating agents acetohydroxamic acid and phos-phoramidate, indicates that nickel is essential to the activity of the enzyme (1). 

The title retains the trivial name for enzymes with the systematic name of urea amidohydrolase and the Enzyme Commission code number of EC 3.5.1.5. Ureases are hydrolases acting on C-N bonds (nonpeptide) in linear amides and thus belong to a group that includes glutaminase, form-amidase, and formyltetrahydrofolate deformylase. The title is plural to emphasize that urease activity may be exhibited by several protein species. Urease, singular, has come to mean by common usage, that particular enzymic protein first crystallized by Sumner from jack bean... 

Urease (urea amidohydrolase) is an enzyme first identified over a hundred years ago in bacterial extracts [22], The presence of urease is a virulence factor for some pathogenic bacteria [23,24], It is now known to occur also in plants, fungi, and invertebrates (see [24,25] for reviews). Urease from jack bean was the first enzyme to be crystallized, in 1926. Almost 50 years later its metal content was reexamined and it was found to contain two atoms of nickel per subunit [26]. Finally in 1995 the crystal structure of the enzyme from the enteric bacterium Klebsiella aerogenes was determined [27], Amino-acid sequence comparisons predict that the structures of the plant and bacterial enzymes are similar, although with different subunit arrangements. 

Several other proteins show a low, but significant amino acid identity with atzA (Table 22.4). All of these, urease-alpha subunit (urea amidohydrolase), cytosine deaminase, and imidazolone-5-propionate hydrolase, catalyze hydrolytic reactions with substrates involved in the metabolism of nitrogenous compounds (Sadowsky et al 1998). A Rhizobium strain capable of atrazine dechlorination has been isolated from a soil that was previously treated with atrazine (Bouqard et al., 1997). This bacterium could not mineralize atrazine, and it accumulated hydroxyatrazine as the sole metabolite after long-term incubations. Interestingly, 22 of the 24 identified amino acids at the N-terminus of the atrazine halidohydrolase from Rhizobium were identical with atzA from Pseudomonas strain ADP. 

Holm, I., Sander, C. (1997). An evolutionary treasure unification of a broad set of amidohydrolases related to urease. Proteins Struct. Funct. Genet. 28 72-82. 

Colher, J. L., Brahamsha, B., and Palenik, B. (1999). The marine cyanobacterium Synechococcus sp. WH7805 requires urease (urea amidohydrolase, EC 3.5.1.5) to utilize urea as a nitrogen source Molecular-genetic and biochemical analysis of the enzyme. Microbiology (UK) 145, 447-459. 

CoUier, J. L., Brahamsha, B., and Palenik, B. (1999). The marine cyanobacterium Synechococcus sp. WH7805 requires urease (urea amidohydrolase, EC 3.5.1.5) to utilize urea as a nitrogen source molecular-genetic and biochemical analysis of the enzyme. Microbiol.—U.K. 145, 447—459. CoUos, Y. (1998). Covariation of ammonium and nitrate uptake in several marine areas Calculation artefact or indication of bacterial uptake Preliminary results from a review of 76 studies. In Integrated Marine System Analysis. Dehairs, F., Elskens, M., and Goeyens, L. (eds.). Vrije Universiteit, Brussel, pp. 121—138. 

Enzymatic methods for the measurement of urea are based on preliminary hydrolysis of urea with urease (urea amidohydrolase, EC 3.5.1.5 main source jack bean meal) to generate ammonium ion, which is then quantified. This approach has been used in end-point, kinetic, conductimet-ric, and dry chemistry systems. ... 

Urease (urea amidohydrolase, EC 3.5.1.5) has the advantage that in the presence of the pH indicator bromocresol purple it produces a sharp unequivocal endpoint with its substrate, urea (Chandler et al, 1982). Moreover, it is absent from mammalian cells. Though urease can also be used for potentiometric EIA (Section 14.6.5), other deaminating enzymes, in particular asparaginase (Gebauer and Rechnitz, 1982), are more promising. The major drawback of urease is the possibility of rapid loss of enzyme activity. Type VII or C-3 urease (Sigma) from Jack beans [Canavalia ensiformis) are the most frequently used enzyme preparations. The physicochemical properties of urease are compiled in Table 10.14. 

Enzymes are also assigned common names, which are usually shorter and more convenient. Common names are derived by adding -ase to the name of the substrate or to a combination of the substrate name and type of reaction. For example, urea amidohydrolase is assigned the common name urease ... 

Urea, allyl-. See Allyl urea Urea, 1-allyl-2-thio-. See Allylthiourea Urea amidohydrolase. See Urease Urea, N-[1,3-bis (hydroxymethyl)-2,5-dioxo-4-imidazolidinyl-N,N -bis (hydroxymethyl)-. See Diazolidinyl urea Urea, butyl-. See N-Butylurea Urea, 1-(5-(t-butyl)-1,3,4-triadiazol-2-yl)-1,3-dimethyl-. See Tebuthiuron Urea, N -(3-chloro-4-methoxyphenyl)-N,N-dimethyl-. See Metoxuron Urea, N-(4-chlorophenyl)-N -[4-chloro-3-(trifluoromethyl) phenyl]-. See Cloflucarban Urea, N-(4-chlorophenyl)-N -(3,4-dichlorophenyl)-. See 3,4,4 -Trichlorocarbanilide... 

CAS 9002-13-5 EINECS/ELINCS 232-656-0 Synonyms Jackbean urease Urea amidohydrolase... 

Hydrolases Amidohydrolases Esterases Urease Acetylcholine esterase Hydrolysis reactions Urea Acetylcholine NH3, CO2 or H+ H +... 

Because most soil enzyme studies deal with crude soil suspensions, or at best partially-purified soil extracts, care must be exercised in assigning an activity to the action of a particular enzyme. This note of caution is perhaps justified by considering the conversion in soils of urea to NH4 and CO2. Urea is an important nitrogenous fertilizer and is a major constituent of the urine of grazing animals, and studies of urea hydrolysis have dominated the soil enzyme literature. It is widely assumed that urea hydrolysis is catalysed by urease (urea amidohydrolase, EC 3.5.1.5). Studies have compared the kinetics and inhibition of urea hydrolysis by soils and by purified ureases, mainly from jack bean, Canavalia ensiformis, Jack bean urease catalyses urea hydrolysis by a pathway in which carbamate is an intermediate. 

Winkler et al. (1985) have described crude and partially purified enzyme preparations from soybean seed coats which catalyze the production of NH4+, CO2, and labile glyoxylate derivatives from ALA. The reaction occurs in the presence of phenyl phosphordiamidate, a potent urease inhibitor, thus supporting an ALA amidohydrolase type of reaction. The enzyme activity had a of... 

Recently, the complete amino acid sequences of the various cyclic amide amidohy-drolases were reported and their homology search revealed that D-hydantoinase and ATP-independent l- and DL-hydantoinase are the members of superfamily of amidohydrolases related to ureases [55]. The superfanuly includes dihydropyrimidinase, allantoinase, dihydroorotase, but not ATP-dependent hydantoinases. As a particular sequence, one aspartic... 

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