Amino, generally groups

The compounds that are identifiable in the sea represent a vast array of biochemicals attributable to the life and death of marine plants and animals. They are generally grouped into six classes based on structural similarities hydrocarbons, carbohydrates, lipids, fatty acids, amino acids, and nucleic acids. Because they represent compounds that can be quantified and understood for their chemical properties and known role in biological systems, a great deal of information has been accumulated over the years about these groups and the specific compounds found within them.7... 

Gas chromatographic separation of -agonist residues is generally complicated by the necessity of derivatization of their polar hydroxyl and amino functional groups. Silyl derivatives are preferentially prepared by treating sample extracts with N,0-bis(trimethylsilyl)trifluoroacetamide (470,471,473,475,483, 487), N-metliyl-N-(trimethylsilyl)trifluoroacetamide (482) or N-methyl-N-(tert-butyldimethylsilyl)trifluoroacetamide (473, 487). Pentafluoropropionic anhydride (481), phosgene (484), trimethylboroxine (480), methyl- and butylboronic acid (489), or a combination of N,O bis(trimethylsilyl)trifluoroacetamide with... 

FIGURE 27-15 General structure of aminoacyl-tRNAs. The amino-acyl group is esterified to the 3 position of the terminal A residue. The ester linkage that both activates the amino acid and joins it to the tRNA is shaded pink. 

Other general synthetic methods introduce the a-amino acid grouping, H2N—CH—C02H, by way of enolate anions. Two selected examples follow. 

Most irreversible enzyme inhibitors combine covalently with functional groups at the active sites of enzymes. These inhibitors are usually chemically reactive, and many of them show some specificity in terms of the amino acid groups which they react with. Diisopropyl fluorophosphate (DFP), for example, forms a covalent adduct with active site serine residues, such as in the serine proteases, and in acetylcholinesterase, which explains its toxic effect on animals. Irreversible enzyme inhibition can be used to identify important active site residues. A special case of irreversible enzyme inhibition is the effect of suicide inhibitors, which are generally chemically unreactive compounds that resemble the substrate of the target enzyme and bind at the active site. The process of enzyme turnover begins, but the inhibitor is so... 

Ammonolysis of halides is usually limited to the aliphatic series, because of the generally low reactivity of aryl halides toward nucleophilic substitution. (However, see Chap. 25.) Ammonolysis has the disadvantage of yielding a mixture of different classes of amines. It is important to us as one of the most general methods of introducing the amino ( NH2) group into molecules of all kinds it can be used, for example, to convert bromoacids into amino acids. The exactly analogous reaction of halides with amines permits the preparation of every class of amine (as well as quaternary ammonium salts, R4N X ). 

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