Ureide


Also found in: Dictionary, Medical, Wikipedia.

Ureide

 

(also known as ureid), any of the derivatives of urea [CO(NH2)2] resulting from the substitution of acyl (RCO) radicals for hydrogen atoms in the NH2 groups. Ureides are crystalline, high-melting compounds; the melting point of acetylurea (CH3CONHCONH2) is 218°C, while that of diacetylurea (CH3CONH)2CO is 153°C. Cyclic ureides are obtained from the reaction of urea with dibasic acids; for example, barbituric acid is obtained by reacting urea with malonic acid or malonic ester. The ureides of brome-substituted acids (bromisoval, carbromal) and cyclic ureides of the barbiturate type are used as sedatives.

References in periodicals archive ?
Ureide accumulation in response to Mn nutrition by eight soybean genotypes with [N.
A 30- to 35-mg sample of dry ground leaf sample from each plot was used to determine shoot ureide concentration using a modified colorimetric procedure (de Silva et al.
The procedure for ureide analysis was as described by Young and Conway (1942) with minor modifications (Streeter, 1979).
Evaluation of the relative ureide content of xylem sap as an indicator of [N.
Relative abundance of ureide (RAU) was calculated from ureide and N[O.
2] fixation sensitivity to water deficits opens the possibility of genotypic segregation based on ureide degradation characteristics.
2] fixation in Jackson to water deficits and have shown that leaf ureide concentrations in Jackson are relatively low under water deficits (Serraj and Sinclair, 1996a; Purcell et al.
We tested the hypothesis that large nodules in combination with lower leaf ureide levels would confer drought-tolerant [N.
2] fixation tolerance to soil-water deficit was the measurement of petiole ureide levels under well-watered conditions.
2] fixation during water deficit was associated with ureide accumulation in shoots.
Exceptions to this idea occur when urea is the chief cause of nitrogen supply, in species in which ureides play an significant physiological role (Martin and Ruby, 2004), when too much application of Zn, Cu, Mn, Fe, Ca, or Mg has been made over many years (Martin and Ruby, 2004), and possibly also in nitrogen-fixing crops grown on mineral-poor or highly nickel-fixing (high pH, high lime) soils.
Concentrations of ureides (allantion and allantoic acid) in xylem sap were measured as the phenylhydrazine derivative of glyoxylate (Young and Conway.