Asparagine chemical structure

Fig. 1.1 Chemical structures of glutamate and aspartate and corresponding amines. Glutamine (a) glutamate (b) asparagine (c) aspartate (d) N-acetylaspartate (e) and N-acetylaspartyl-glutamate (f)...

Experimental values are based on a different N-terminal group an asparagine-quinoline moiety replacing NH2-Ala-Ala in the compounds D, IV, V, and VIII. See Figure lb for the chemical structures of I-Vm. 

FIGURE 13.10 Typical chemical structure of asparagines derivative. 

Surfactin is a cyclic lipopeptide produced by B. subtilis.The chemical structure consists of several variants differing in their fatty acid chain and their peptide moiety.They comprise a peptide loop of seven amino acids (t-asparagine, L-leucine, glutamic acid, L-leucine, L-valine and two D-leucines), and a a, -hydroxy C13-C15 fatty acid chain (Figure 14.7). 

L-aspartic acid, also known as c-asparagic add, L-aminosuccinic acid, and 2-aminobutanedioic acid (denoted Asp or D), is a nonessential, acidic amino acid, as can be seen from the chemical structure (Fig. 15.3). On reviewing the literature, it becomes evident that Asp was discovered by Plisson in 1827, and it was obtained by simply boiling asparagine with a base (http // www.inchem.org/documents/icsc/icsc/eicsl439.htm). Aspartic acid naturally occurs in Leavo (L-form) and/or Dextro (o-form). 

Until recently, the catalytic role of Asp ° in trypsin and the other serine proteases had been surmised on the basis of its proximity to His in structures obtained from X-ray diffraction studies, but it had never been demonstrated with certainty in physical or chemical studies. As can be seen in Figure 16.17, Asp ° is buried at the active site and is normally inaccessible to chemical modifying reagents. In 1987, however, Charles Craik, William Rutter, and their colleagues used site-directed mutagenesis (see Chapter 13) to prepare a mutant trypsin with an asparagine in place of Asp °. This mutant trypsin possessed a hydrolytic activity with ester substrates only 1/10,000 that of native trypsin, demonstrating that Asp ° is indeed essential for catalysis and that its ability to immobilize and orient His is crucial to the function of the catalytic triad. 

Chemical Name L-Asparagine amidohydrolase Common Name Colapase L-Asnase Structural Formula ... 

The influence of secondary structure on reactions of deamidation has been confirmed in a number of studies. Thus, deamidation was inversely proportional to the extent of a-helicity in model peptides [120], Similarly, a-hel-ices and /3-turns were found to stabilize asparagine residues against deamidation, whereas the effect of /3-sheets was unclear [114], The tertiary structure of proteins is also a major determinant of chemical stability, in particular against deamidation [121], on the basis of several factors such as the stabilization of elements of secondary structure and restrictions to local flexibility, as also discussed for the reactivity of aspartic acid residues (Sect. 6.3.3). Furthermore, deamidation is markedly decreased in regions of low polarity in the interior of proteins because the formation of cyclic imides (Fig. 6.29, Pathway e) is favored by deprotonation of the nucleophilic backbone N-atom, which is markedly reduced in solvents of low polarity [100][112],... 

H Chemical Shifts" of Structural-reporter Groups of Constituent Monosaccharides, and of Amino Acid Protons for Glyco-asparagines... 

Compound 56 is a branched glyco-asparagine possessing GlcNAc-1 as the disubstituted residue it has been isolated from the urine of a patient suffering from aspartylglucosaminuria.52,89 The 360-MHz, H-n.m.r. spectrum of 56 is presented in Fig. 40. The chemical shifts of the structural-reporter groups of 56 are compiled in Table XXIII. 

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