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Query: EC:3.5.1.5 (urease)
 7,257 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A series of dipeptidyl hydroxamic acids (H-X-Gly-NHOH: X = amino acid residues) was synthesized, and the inhibitory activity against Jack bean and Proteus mirabilis ureases [EC 3.5.1.5] was examined. A number of H-X-Gly-NHOH inhibited Jack bean urease with an I50 of the order of 10(-6) M and inhibited Proteus mirabilis urease with an I50 of the order of 10(-5) M. The inhibition against Jack bean urease was more potent than that with the corresponding aminoacyl hydroxamic acids (H-X-NHOH).
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PMID:Inhibition of urease activity by dipeptidyl hydroxamic acids. 146 6

The detrimental effects of excessive Ni on plant growth have been well known for many years. More recent evidence indicates that Ni is required in small amounts for normal plant growth and development. Ni is an essential component of urease in plants and microorganisms. A deficiency of Ni in plants is reported to result in necrotic lesions in leaves in response to toxic accumulations of urea. Urease plays an essential role in mobilization of nitrogenous compounds in plants, a process that is especially important during seed germination and fruit formation when protein reserves are degraded into amino acids. Arginine, an abundant amino acid in plants, when degraded produces urea as a product and urease is needed for urea utilization. Theories of urea formation during allantoin degradation in Glycine max have been recently refuted. In G. max ureides apparently are metabolized via an amidohydrolase reaction with subsequent degradation of ureidoglycine, yielding glyoxylate, NH+4 and CO2. No evidence is available for the formation of urea in this pathway. Nitrogen-fixing symbionts, such as Rhizobium and Bradyrhizobium, contain two known Ni enzymes: urease and hydrogenase. Optimum growth of nodulated legumes and actinorhizal plants may depend on an adequate supply of Ni to meet the requirements of the Ni-requiring enzymes in host plants and endophytes. The seeds of severely Ni-deficient Hordeum are completely inviable, thus providing conclusive evidence for the essentiality of Ni for this species. The evidence indicates that Ni must be added to the list of micronutrient elements generally required by plants.
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PMID:Nickel as a micronutrient element for plants. 307 27

We report the first isolation of a low-copy-number gene from a complex higher plant (soybean) genome by direct screening with synthetic oligodeoxynucleotide (oligo) probes. A synthetic, mixed, 21-nucleotide (nt) oligo (21-1) based on a seven amino acid (aa) sequence from soybean seed urease, was used to screen genomic libraries of soybean (Glycine max [L.] Merr.) in the lambda Charon 4 vector. Twenty homologous clones were recovered from a screen of 500,000 plaques. These were counterscreened with embryo-specific cDNA (15-2 cDNA) made by priming with a second, mixed 15-nt oligo (15-2), based on a Jack bean (Canavalia ensiformis) urease peptide [Takishima et al., J. Natl. Def. Med. Coll. 5 (1980) 19-23]. Five out of 20 clones were homologous to 15-2 cDNA and proved to be identical. Nucleotide sequence analysis of representative clone E15 confirmed that it contained urease sequences. Subclones of E15 homologous to the oligo probes contain a deduced amino acid sequence which matches 108 of 130 aa residues of an amino acid run in a recently published [Mamiya et al., Proc. Jap. Acad. 61B (1985) 359-398] complete protein sequence for Jack-bean seed urease. Using clone E15 as a probe of soybean embryonic mRNA revealed a homologous 3.8-kb species that is the size of the urease messenger. This species is absent from mRNA of embryos of a soybean seed urease-null mutant. However, both urease-positive and urease-null genomes contain the 11-kb DNA fragment bearing urease sequences.
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PMID:Recovery of a soybean urease genomic clone by sequential library screening with two synthetic oligodeoxynucleotides. 360 52

1. Urease of specific activity 160-180 Sumner units/g. (Sumner, 1951) was purified from jack-bean meal. The preparation was pure on the basis of polyacryl-amide-gel electrophoresis and N-terminal studies. 2. By using both the 1-fluoro-2,4-dinitrobenzene method and the phenyl isothiocyanate method a single N-terminal methionine residue was found. 3. A single C-terminal sequence -Tyr-Leu-Phe was found by studies with carboxypeptidase A, carboxypeptidase B and hydrazinolysis. 4. N-Bromosuccinimide cleavage showed that five unique tryptophan sequences were present: Trp-Ala, Trp-Glu, Trp-Gly, Trp-Met and Trp-Arg. 5. Polyacrylamide-gel electrophoresis in sodium dodecyl sulphate showed that urease had a subunit molecular weight of 76000. 6. The yield of N- and C-terminal amino acids, the number of tryptic peptides and tryptophan sequences and the above polyacrylamide-gel electrophoretic measurement all suggest that urease contains a single structural subunit of molecular weight 75000.
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PMID:The subunit structure of jack-bean urease. 538 87

1. A new form of enzymically active jack-bean [Canavalia ensiformis (L.) DC] urease corresponding to an S(20,w) value of 11.8s and a molecular weight of 260000 was investigated. 2. Conversion of 18s urease (EC 3.5.1.5) into the 12s form depends on both low protein concentration and pH. Above pH5.3 urease exists in the 18s form and below pH4.8 in the 12s form; between these two pH values a 12s-18s rapid-equilibrium process is observed. 3. Comparison of the properties of 18s and 12s urease indicated no major differences. 4. A survey of other good urease sources revealed that the 12s form can also be obtained from soya bean (Glycine soja Sieb. and Zucc. cultivar Biloxi) and the bacterium Bacillus pasteurii (Miguel) Migula, but not from watermelon (Citrullus vulgaris Schrad. cultivar Congo). 5. The 12s forms from jack bean and Bacillus pasteurii did not hybridize.
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PMID:Physical and chemical studies of a low-molecular-weight form of urease. 569 53

Helicobacter pylori (HP) produces strong urease [EC 3.5.1.5], which is considered to play a role in the pathogenesis of gastritis and peptic ulcers. Inhibitions against this enzyme have been studied with hydroxamic acid (HXA) derivatives of aliphatic or aromatic carboxylic acids, amino acids and dipeptides. A number of HXAs potently inhibited the urease (I50 values were near the order of 10(-6)M), and H-Ile-Gly-NHOH (I50 = 0.20 x 10(-6)M) was the most potent inhibitor among the derivatives. HP urease was inhibited more potently, in general, than Jack bean (JB) urease by HXAs, and a correlation between the chemical structures of HXA derivatives and their inhibitory effects on HP urease was observed, in comparison with JB urease.
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PMID:Inhibition of Helicobacter pylori urease activity by hydroxamic acid derivatives. 787 52

The urease from the ascomycetous fission yeast Schizosaccharomyces pombe was purified about 4000-fold (34% yield) to homogeneity by acetone precipitation, ammonium sulfate precipitation, DEAE-Sepharose ion-exchange column chromatography, and if required, Mono-Q ion-exchange fast protein liquid chromatography. The enzyme was intracellular and only one species of urease was detected by nondenaturing polyacrylamide gel electrophoresis (PAGE). The native enzyme had a M(r) of 212 kDa (Sepharose CL6B-200 gel filtration) and a single subunit was detected with a M(r) of 102 kDa (PAGE with sodium dodecyl sulfate). The subunit stoichiometry was not specifically determined, but the molecular mass estimations indicate that the undissociated enzyme may be a dimer of identical subunits. The specific activity was 700-800 micromols urea.min-1.mg protein-1, the optimum pH for activity was 8.0, and the Km for urea was 1.03 mM. The sequence of the amino terminus was Met-Gln-Pro-Arg-Glu-Leu-His-Lys-Leu-Thr-Leu-His-Gln-Leu-Gly-Ser-Leu-Ala and the sequence of two tryptic peptides of the enzyme were Phe-Ile-Glu-Thr-Asn-Glu-Lys and Leu-Tyr-Ala-Pro-Glu-Asn-Ser-Pro-Gly-Phe-Val-Glu-Val-Leu-Glu-Gly-Glu-Ile- Glu- Leu-Leu-Pro-Asn-Leu-Pro. The N-terminal sequence and physical and kinetic properties indicated that S. pombe urease was more like the plant enzymes than the bacterial ureases.
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PMID:Purification and characterization of urease from schizosaccharomyces pombe. 874 56

Arginase (EC 3.5.3.1) transcript level and activity were measured in soybean (Glycine max L.) embryos from the reserve deposition stage to postgermination. Using a cDNA probe for a small soybean arginase gene family, no transcript was detected in developing embryos. However, arginase transcripts increased sharply on germination, reaching a maximum at 3 to 5 d after germination. There was low but measurable in vitro arginase specific activity in developing embryos (less than 6% of seedling maximum). During germination arginase specific activity increased in parallel with the sharply increasing arginase transcript level. Seedling arginase activity was largely localized in cotyledons. Arginase activity was assayed in vivo by measuring urea accumulation in a urease-deficient mutant. No urea was detected in developing embryos, whereas accumulated urea paralleled arginase specific activity and transcript level in germinating seedlings. As in planta embryos, cultured cotyledons did not accumulate urea when arginine (Arg) was provided with other amino acids in a "mock" seed-coat exudate. Arg as the sole nitrogen source was converted to urea but did not support cotyledon growth. There appeared to be a lack of recruitment of the low-level arginase activity to hydrolyze free Arg in developing embryos, thus avoiding a futile urea cycle.
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PMID:Arginase is inoperative in developing soybean embryos. 988 Mar 72

The hypothesis that soybean (Glycine max L. [Merrill]) catabolizes ureides to urea to a physiologically significant extent was tested and rejected. Urease-negative (eu3-e1/eu3-e1) plants were supported by fixed N2 or by 2 mM NH4NO3, so that xylem-borne nitrogen contained predominantly ureides (allantoin and allantoic acid) or amide amino acids, respectively. Seed nitrogen yield was equal on either nitrogen regime, although 35-d-old fixing plants accumulated about 6 times more leaf urea. In callus, lack of an active urease reduced growth on either arginine or allantoin as the sole nitrogen source, but the reduction was greater on arginine (73%) than on allantoin (39%). Furthermore, urease-negative cells accumulated 17 times more urea than urease-positive cells on arginine; for allantoin the ratio was 1.8. Urease-negative callus accumulated urea at 3% the rate of seedlings. To test whether urea accumulating in urease-negative seedlings was derived from ureides, seeds were first allowed to imbibe in 1 mM allopurinol, an inhibitor of ureide formation. Seedling ureides were decreased by 90%, but urea levels were unchanged. Thus, ureides are poor precursors of urea, which was confirmed in seedlings that converted no more than 5% of seed-absorbed [14C-ureido]allantoate to [14C]urea, whereas 40 to 70% of [14C-guanido]arginine was recovered as [14C]urea.
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PMID:Urease Is Not Essential for Ureide Degradation in Soybean. 1222 87

Plant orthologs of the bacterial urease accessory genes ureD and ureF, which are required for the insertion of the nickel ion at the active site, have been isolated from soybean ( Glycine max L. Merr.), tomato ( Lycopersicon esculentum) and Arabidopsis thaliana. The functionality of soybean UreD and UreF was tested by measuring their ability to complement urease-negative mutants of Schizosaccharomyces pombe, a eukaryote which produces a "plant-like" urease of ~90 kDa. The S. pombe ure4 mutant was complemented by a 12-kb fragment of S. pombe genomic DNA, which was shown by PCR to contain a putative ureD gene. However, ure4 was not complemented by a UreD cDNA soybean, expressed under the control of a strong promoter. In contrast, an S. pombe ure3 mutation was complemented by both a 10-kb fragment of S. pombe DNA containing ureF and the UreF cDNA from soybean. Soybean Eu2 is a candidate urease accessory gene; its product cooperates with the Eu3 protein in activating apourease in vitro. However, the sequences of UreD and UreF transcripts from two eu2/eu2 mutants, recovered as RT-PCR products, revealed no mutational alteration, suggesting that Eu2 encodes neither UreD nor UreF.
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PMID:Activation of the urease of Schizosaccharomyces pombe by the UreF accessory protein from soybean. 1247 50


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