Glutamine from asparagine

E Sondheimer, RW Holley. Imides from asparagine and glutamine, (effect of alkali... 

The ammonia produced from asparagine and glutamine is released into the hepatic portal vein, for removal by the liver and conversion to urea. The concentration of ammonia in the blood in the hepatic portal vein is about ten times higher than in the hepatic vein, indicating the quantitative importance of the liver in removing this ammonia. 

A direct detection method was recently developed for these adducts in stratum comeum of human skin based on immunofluorescence microscopy (30). Three partial sequences of keratins containing glutamine or asparagine, adducted with a 2-hydroxyethyl-thioethyl group at the omega-amide function, were synthesized and used as antigens for raising antibodies. After immunization, monoclonal antibodies were obtained with affinity for keratin isolated from human callus exposed to 50 xM sulfur mustard (see Plate 1). In contrast to the immunochemical... 

The free carboxyl groups of pig heart lipoamide dehydrogenase have been determined as 56 per FAD (64). The glutamine plus asparagine content is, by difference, 35. It can then be calculated that the net charge on the protein will depend on the effective pK values of the histidine residues and will vary with pH from -(-5 to —6 per FAD. Amide data for thioredoxin reductase 31) allow a similar calculation The charge can vary from - -2 to —8 per FAD. 

Whereas heat precipitation is used only very rarely with proteins originating from mesophilic organisms, it is a very common step in the purification protocols of proteins from thermophilic organisms, which have been doned and expressed in E. coli. However, even in these cases, it is important that the incubation time is kept as short as possible to minimise deamidation of glutamine and asparagine residues. 

Tower et al. (1962) have employed enzymatic hydrolysis with pancreatin preparations for liberation of glutamine and asparagine from proteins. Under the conditions employed, proteins were not hydrolyzed to an extent of more than 50-80 %, but after correcting for incomplete hydrolysis, yields of the two amides were in excellent agreement with theoretical values. 

Simple imide link from asparagine or glutamine to aspartic or glutamic acids... 

The formation of asparagine from aspartate is chemically analogous to the formation of glutamine from glutamate. Both transformations are amidation reactions and both are driven by the hydrolysis of ATP. The actual reactions are different, however. In bacteria, the reaction for the asparagine synthesis is... 

The upper right comer of the HSQC spectmm of l N-labeled apoLp-III shown in Figure 2, panel A contains numerous doublet crosspeaks which are derived from side chain amines of glutamine and asparagine residues. Since apoLp-III is rich in glutamine and asparagine (25 of the 166 amino acids), this region of the spectrum is... 

Ammonium ions are produced by the catabolism of a number of amino acids. Glutamate dehydrogenase is the major source of ammonium ions in the body. Ammonium ions are also produced from the catabolic pathways of serine, histidine, tryptophan, glycine, glutamine, and asparagine. L-Amino acid oxidase and... 

The fatty, tallowy-smelling aroma compound 2-pentylpyridin (56), which has been identified in roasted sesame seeds [77], is formed from the reaction of a fat oxidation product, 2,4-decadienal, with ammonia from the degradation of amino acids like glutamine and asparagine [78] (cf. Fig. 3.33). 

XAES) shows that CuLj chelates (LH = glutamine or asparagine) have distorted octahedral structures. The oxidative decarboxylation product of Gly-Gly-L-His and Cu(OH)2 is four-co-ordinate and square planar decarboxylation occurs at C-5 with deprotonation at C-4 to give a C==C system. Amine adducts of bis(ben-zoyl-/5-alaninato)copper(ii) have been isolated and characterized. Equilibrium constants have been reported for copper(ii) complexes of histidylhistidine from pH-titration data. " Qualitative analysis of the Cotton effect of d-d transitions of copper(ii) complexes with optically active acids has been obtained. ... 

In transamination reactions, amino groups are transferred from one carbon skeleton to another. In reductive animation, amino acids are synthesized by the incorporating of free NH) or the amide nitrogen of glutamine or asparagine into a-keto acids. Ammonium ions are also incorporated into cellular metabolites by the animation of glutamate to form glutamine. 

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