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Plant urease

Nickel Essential trace element Chicks and rats raised on deficient diet show impaired liver function and morphology stabilizes coiled ribosomes. Active metal in several hydrogenases and plant ureases Very toxic to most plants, moderately so to mammals carcinogenic. Local industrial pollutant of air and water. [Pg.485]

PoiACCO JC (1977) Is nickel a universal component of plant ureases Plant Sd Lett 10 249—255. [Pg.862]

Plant urease (e.g., from raw soybeans) may enhance the hydrolysis of uroa. [Pg.341]

Enzymes are proteins of high molecular weight and possess exceptionally high catalytic properties. These are important to plant and animal life processes. An enzyme, E, is a protein or protein-like substance with catalytic properties. A substrate, S, is the substance that is chemically transformed at an accelerated rate because of the action of the enzyme on it. Most enzymes are normally named in terms of the reactions they catalyze. In practice, a suffice -ase is added to the substrate on which die enzyme acts. Eor example, die enzyme dial catalyzes die decomposition of urea is urease, the enzyme dial acts on uric acid is uricase, and die enzyme present in die micro-organism dial converts glucose to gluconolactone is glucose oxidase. The diree major types of enzyme reaction are ... [Pg.21]

Until the discovery in 1975 of nickel in jack bean urease (which, 50 years previously, had been the first enzyme to be isolated in crystalline form and was thought to be metal-free) no biological role for nickel was known. Ureases occur in a wide variety of bacteria and plants, catalyzing the hydrolysis of urea,... [Pg.1167]

Todd, G. W. Effect of low concentrations of ozone on the enzymes catalase, peroxidase, papain and urease. Physiol. Plant. 11 457-463, 1958. [Pg.583]

Urease. An enzyme of the hydrolase class that catalyzes the hydrolysis of urea to COj and ammonia. It is nickel protein found in micro-organisms and plant that is frequently used in clinical assays of plasma urea concentrations. [Pg.578]

Nickel has long been suspected to be an essential trace element for living organisms, but the identification of its functions in molecular terms is relatively recent. The first nickel protein to be identified was urease (urea ammonia hydrolase) (i). This was demonstrated 49 years after the original isolation and crystallization of the enzyme by Sumner (2). This enzyme is of widespread occurrence, and the specific requirement for nickel explains many of the effects of nickel deficiency in plants (3, 4). [Pg.297]

In Azotobacter vinelandii, urease appears to be synthesized only when urea or thiourea is present (75). A study of the urease constitutive in Corynebacterium renale (76) did not reveal features remarkably different from the plant enzyme. A similar conclusion was reached in the characterization of a highly purified enzyme from B. pasteurii (77). Stewart (78) has devised a medium for the detection of urease activity in pseudomonads and has resolved uncertainties that have developed in the literature. It has been reported that Sarcina ureae produces urease as an exoenzyme (79). [Pg.14]

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. [Pg.234]

The composition, visible spectroscopy, and catalytic properties of urease have been reviewed by Blakeley and Zemer [25] and by Hausinger [2]. The urease from jack bean is typical of the enzymes from plants. It has a protein of relative... [Pg.234]

It has not been possible so far to establish that Cr is an essential element required by plants, however, addition of Cr to soils deficient in the element has been shown to increase growth rates and yields of potatoes, maize, rye, wheat or oats (Scharrer and Schropp, 1935 Huffman and Allaway, 1973 Bertrand and De Wolf, 1986). Nickel appears to be an essential element for plants (Farago and Cole, 1988). Zerner and coworkers (Dixon et al., 1975) demonstrated that urease isolated from jack bean (Canavalia ensiformis) was a nickel enzyme. Eskew et al. (1983) have shown that Ni is an essential micronutrient for legumes. Most plants contain nickel in the range 1 - 6 mg kg-1 (Vanselow, 1966 Hutchinson, 1981). The uptake of Ni is enhanced by low pH values, and available nickel increases at pH less than 6.5 as a consequence of the breakdown of Ni complexes in the soil with Fe and Mn oxides. Uptake of nickel by plants and questions of toxicity and tolerance have been reviewed by Farago and Cole (1988). Nickel toxicity toward plants has been reviewed by Vanselow (1966) and Hutchinson (1981). [Pg.51]

Roughly 30% of enzymes are metalloenzymes or require metal ions for activity and the present chapter will concentrate on the chemisty and structure of the plant metalloenzymes. As analytical methods have improved it has been possible to establish a metal ion requirement for a variety of enzymes which were initially considered to be pure proteins. A dramatic example is provided by the enzyme urease isolated from Jack beans and first crystallised by Sumner (1926) (the first enzyme to be crystallised). Sumner defined an enzyme as a pure protein with catalytic activity, however, Zerner and his coworkers (Dixon et al., 1975) established that urease is in fact a nickel metalloenzyme. Jack bean urease contains two moles of nickel(II) per mole of active sites and at least one of these metal ions is implicated in its mechanism of action. [Pg.108]

The urea is excreted through the kidneys and broken down to carbon dioxide and ammonia by plants and microorganisms. The enzyme urease causes this conversion. [Pg.76]

This reaction is catalyzed by a highly specific enzyme, urease. Urease is present in a number of bacteria and plants. The most common source of the enzyme is jack bean or soybean. Urease was the first enzyme that was crystallized. Sumner, in 1926, proved unequivocally that enzymes are protein molecules. [Pg.487]


See other pages where Plant urease is mentioned: [Pg.67]    [Pg.845]    [Pg.1671]    [Pg.249]    [Pg.67]    [Pg.845]    [Pg.1671]    [Pg.249]    [Pg.414]    [Pg.104]    [Pg.403]    [Pg.291]    [Pg.433]    [Pg.485]    [Pg.9]    [Pg.257]    [Pg.258]    [Pg.76]    [Pg.116]    [Pg.485]    [Pg.878]    [Pg.1378]    [Pg.1074]    [Pg.1074]    [Pg.1651]    [Pg.2]    [Pg.643]    [Pg.643]    [Pg.325]    [Pg.235]    [Pg.241]    [Pg.69]    [Pg.155]    [Pg.287]   
See also in sourсe #XX -- [ Pg.845 ]




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