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Aminoacid chemical nature

The isolation and nature of the acetylcholine receptor was described in Section 2.1. Of the various products of this work, Changeux s micro-sacs are particularly welcome, as they enable much experimentation with drugs to be carried out under conditions more versatile than when the receptors are in the synapse. We shall learn much more about the chemical nature of the active site when the receptor is available, quite pure and in greater quantity, for determination of aminoacid sequence and then for X-ray diffraction study. [Pg.502]

In spite of the fact that biotechnology rather than chemical processing will probably provide the future greatly needed chirally pure compounds (ref. 1), we believe that simple chemical reactions starting from chiral natural compounds and proceeding under stereochemical control will eventually retain full importance. On the above grounds, we report on simple reactions which start from a-aminoacids, as an example of utilization of natural compounds, and move to related bromine containing compounds (Fig. 1). [Pg.160]

An amazing selectivity and efficiency characterizes chemical reactions carried out in Nature that are catalyzed by specific enzymes. The fact that living organisms are built almost exclusively (see, however, [15]) from L-aminoacids... [Pg.98]

Over the past 10 years, our understanding of enzymes which effect the difficult chemical process of C6H bond cleavage has increased dramatically (Stubbe, 1989 Klinman, 1996). We know that nature employs both metal ions and reactive organic cofactors, such as radicals and quinones, derived by post-translational modification of aminoacids in the polypeptide chain of the enzyme. The two enzymes to be described in the present review are good examples galactose oxidase employs copper and a tyrosine covalently cross-linked to a cysteine to stabilize a radical whilst amine oxidases employ copper and tyrosine-derived quinones. There is subtle interplay between the roles played by copper in the biogenesis of these novel cofactors and in the catalytic cycle of the oxidases. [Pg.183]

Schraml et al.(137) found that the Si resonances of a series of silyl ester, alkoxy-silyl, and amino-silyl derivatives appear in different regions of the spectrum. On the basis of this information they suggested that Si NMR can be used for the structure elucidation of silylated hydroxy- or aminoacids. The silicon chemical shifts for DL-serine [55] and DL-threonine [56 ] are shown in ppm. The variation in the shielding for the alkoxy-silyl group demonstrates the previously noted sensitivity of Si NMR to the nature of R in Mc3SiOR. (140)... [Pg.270]

The most important and universal type of chemical equilibria to which a heme protein is subjected in natural environments is pH equilibria, involving the protein aminoacid residues and the ionizable groups of the porphyrin, the propionate side chains. Beside the effects on the overall protein structure, which are outside the scope of this review, the major consequences of proton equilibria may be the changes of the heme reduction potential (electron affinity), called the redox-Bohr effect (see Sect. 3.2), by analogy to the pH effect on the oxygen affinity of hemoglobin (Bohr effect). [Pg.70]

We are not justified in considering the combination of proteids with acids or alkalis as salts. Rather must we consider that similar relations exist as in the case of the purple of Cassius. On the other hand it cannot be denied that the purely chemical point of view has much in its favor, especially with regard to the decomposition products which consist principally of aminoacids, amphoteric electrolytes. In this consideration the colloidal nature of the proteids must not be lost sight of, for ultramicrons appear in quantity in the case of the most important members. [Pg.209]

Fattomsso, E. and Piattelli, E. (1980) Aminoacids from marine algae, in Marine Natural Products Chemical and Biolo al Perspectives, vol. Ill (ed. P.J. Scheuer), Academic Press, London, New York, pp. 95—140. [Pg.2025]


See other pages where Aminoacid chemical nature is mentioned: [Pg.998]    [Pg.182]    [Pg.189]    [Pg.212]    [Pg.222]    [Pg.278]    [Pg.144]    [Pg.548]    [Pg.1364]    [Pg.188]    [Pg.22]    [Pg.197]    [Pg.122]    [Pg.95]    [Pg.383]    [Pg.175]    [Pg.246]    [Pg.234]    [Pg.370]    [Pg.125]   
See also in sourсe #XX -- [ Pg.8 , Pg.34 , Pg.136 ]




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