Amino utilization

Urea is also used as feed supplement for mminants, where it assists in the utilization of protein. Urea is one of the raw materials for urea—formaldehyde resins. Urea (with ammonia) pyrolyzes at high temperature and pressure to form melamine plastics (see also Cyanamides). Urea is used in the preparation of lysine, an amino acid widely used in poultry feed (see Amino acids Feeds and feed additives, petfoods). It also is used in some pesticides. 

Sulfur deficiency usually is not a problem for mminants because the mminal microflora can utilize sulfur-containing amino acids. A deficiency can occur, however, when an NPN source is fed. L-Methionine [63-68-3] is the most biologically available source of sulfur (21). Various sulfates are intermediate in sulfur avadabiHty, and elemental sulfur is the least available source of sulfur. 

Synthetic utility of stereoselective alkylations in natural product chemistry is exemplified by the preparation of optically active 2-arylglycine esters (38). Chirally specific a-amino acids with methoxyaryl groups attached to the a-carbon were prepared by reaction of the dimethyl ether of a chiral bis-lactam derivative with methoxy arenes. Using SnCl as the Lewis acid, enantioselectivities ranging from 65 to 95% were obtained. 

The nutrient sparing effect of antibiotics may result from reduction or elimination of bacteria competing for consumed and available nutrients. It is also recognized that certain bacteria synthesize vitamins (qv), amino acids (qv), or proteins that may be utilized by the host animal. Support of this mode of action is found in the observed nutritional interactions with subtherapeutic use of antibiotics in animal feeds. Protein concentration and digestibiHty, and amino acid composition of consumed proteins may all influence the magnitude of response to feeding antibiotics. Positive effects appear to be largest... 

Those herbicides that block mitotic entry decrease or prevent the formation of mitotic figures in meristems. Amino acid, protein, RNA, DNA, and ATP synthesis and/or utilization can all attest cell growth (163,166). Although not registered as herbicides, cycloheximide [66-81-9] inhibits mitotic entry by inhibiting protein synthesis (167) hydroxyurea/727-(97-/7 inhibits DNA synthesis (168) and actinomycin D [50-76-0] nh2oix.s RNA synthesis (167). 

Formaldehyde reacts with the hydrogen on the a-carbon of the fatty acid from which the oxazoline was formed to yield a vinyl monomer which can be polymerized or utilized for synthesis (4). Thus, esters of the oxazoline formed from TRIS AMINO undergo the reaction... 

Because they are similar, the aLkanolamines often can be used interchangeably. However, cost/perfomiance considerations generally dictate a best choice for specific appHcations. AMPD is manufactured in very low volumes for use as a reagent in certain medical diagnostic tests, although some is used in certain cosmetic products. 2-Ainino-1-butanol is used primarily as a taw material for the synthesis of ethambutol [74-55-5] an antituberculosis dmg. The first step in the synthesis of this dmg is the resolution of AB into its optical isomers because only (i)-2-amino-l-butanol, [5856-62-2] is utilized in this synthesis. 

Biomedical Applications. TRIS AMINO is used for a number of purposes in its pure form, it is an acidimetric standard the USP grade can be utilized intraveneously for therapeutic control of blood acidosis TRIS AMINO also is useful in genetic engineering as a buffering agent for enzyme systems, industrial protein purification, and electrophoresis. AMP has found use as a reagent in enzyme-linked immunoassays. The primary appHcation is for alkaline phosphatase assays. 

Synthetic Applications. Oxazolines, which ate synthesized as indicated above, have been utilized in many different appHcations (25). When used in resin formulations, AMP, AEPD, and TRIS AMINO can incorporate the oxazoline stmeture into the polymer stmeture (26). Because they ate polyols, both AEPD and TRIS AMINO can be used in polyester resin modification. Oxazoline alkyd films ate characterized by improved performance, particularly salt-spray resistance and gloss (see Alkyd resins Coatings, special purpose, high performance). 

In these cases, it is better to protect the carboxyl group. Optimized conditions for A/-acetylation have been studied (78). A/-Acylation can be utilized for protecting the amino group in the reaction of amino acids, for example in peptide synthesis. 

The existence of protein receptors in the tongues of mice and cows have been shown. Monosodium L-glutamate MSG [142-47-2] is utilized as a food flavor enhancer in various seasonings and processed foods. D-Glutamate is tasteless. L-Aspartic acid salt has a weaker taste of umami. Glycine and L-alanine are slightly sweet. The relationship between taste and amino acid stmcture has been discussed (222). 

Table 2. a-Amino, Acyl, or Ureido Penicillins Under Investigation or Exhibiting Limited Clinical Utility... 

Amine boranes have been examined by a variety of spectroscopic methods (24—29). The boron-substituted alpha-amino acids have been utilized in animal model studies. These compounds along with their precursors and selected derivatives have been shown to possess antineoplastic, antiarthritic, and hypolipidemic activity (30—32). The boron amino acid analogues are also being evaluated for possible utility in boron neutron capture therapy (BNCT) (33). 

The reduction of (aLkylarnino)haloboranes using hydride reagents can provide a convenient route to (aLkylamino)boranes for example, LiAlH has been utilized to prepare bis (dimethyl amino)borane [23884-11-9] from chi orobis (dimethyl amino)borane [6562-41-0] (68). When this same strategy is appHed to (bis(trimethylsi1y1)amino)ch1oro((trimethylsi1y1)amino)borane [10078-93-0] the expected compound is obtained along with the formation of two... 

Iminoboianes have been suggested as intermediates in the formation of compounds derived from the pyrolysis of azidoboranes (77). The intermediate is presumed to be a boryl-substituted nitrene, RR BN, which then rearranges to the amino iminoborane, neither of which has been isolated (78). Another approach to the synthesis of amino iminoboranes involves the dehydrohalogenation of mono- and bis(amino)halobotanes as shown in equation 21. Bulky alkah-metal amides, MNR, have been utilized successfully as the strong base,, in such a reaction scheme. Use of hthium-/i /f-butyl(ttimethylsilyl)amide yields an amine, DH, which is relatively volatile (76,79). 

There are two distinct groups of aldolases. Type I aldolases, found in higher plants and animals, require no metal cofactor and catalyze aldol addition via Schiff base formation between the lysiae S-amino group of the enzyme and a carbonyl group of the substrate. Class II aldolases are found primarily ia microorganisms and utilize a divalent ziac to activate the electrophilic component of the reaction. The most studied aldolases are fmctose-1,6-diphosphate (FDP) enzymes from rabbit muscle, rabbit muscle adolase (RAMA), and a Zn " -containing aldolase from E. coli. In vivo these enzymes catalyze the reversible reaction of D-glyceraldehyde-3-phosphate [591-57-1] (G-3-P) and dihydroxyacetone phosphate [57-04-5] (DHAP). 

Biological systems depend on specific detailed recognition of molecules that distinguish between chiral forms. The translation machinery for protein synthesis has evolved to utilize only one of the chiral forms of amino acids, the L-form. All amino acids that occur in proteins therefore have the L-form. There is, however, no obvious reason why the L-form was chosen during evolution and not the D-form... 

The side chains of the 20 different amino acids listed in Panel 1.1 (pp. 6-7) have very different chemical properties and are utilized for a wide variety of biological functions. However, their chemical versatility is not unlimited, and for some functions metal atoms are more suitable and more efficient. Electron-transfer reactions are an important example. Fortunately the side chains of histidine, cysteine, aspartic acid, and glutamic acid are excellent metal ligands, and a fairly large number of proteins have recruited metal atoms as intrinsic parts of their structures among the frequently used metals are iron, zinc, magnesium, and calcium. Several metallo proteins are discussed in detail in later chapters and it suffices here to mention briefly a few examples of iron and zinc proteins. 

Secondary amines cannot form imines, and dehydration proceeds to give carbon-carbon double bonds bearing amino substituents (enamines). Enamines were mentioned in Chapter 7 as examples of nucleophilic carbon species, and their synthetic utility is discussed in Chapter 1 of Part B. The equilibrium for the reaction between secondary amines and carbonyl compounds ordinarily lies far to the left in aqueous solution, but the reaction can be driven forward by dehydration methods. 

The study of acid-base interaction is an important branch of interfacial science. These interactions are widely exploited in several practical applications such as adhesion and adsorption processes. Most of the current studies in this area are based on calorimetric studies or wetting measurements or peel test measurements. While these studies have been instrumental in the understanding of these interfacial interactions, to a certain extent the interpretation of the results of these studies has been largely empirical. The recent advances in the theory and experiments of contact mechanics could be potentially employed to better understand and measure the molecular level acid-base interactions. One of the following two experimental procedures could be utilized (1) Polymers with different levels of acidic and basic chemical constitution can be coated on to elastomeric caps, as described in Section 4.2.1, and the adhesion between these layers can be measured using the JKR technique and Eqs. 11 or 30 as appropriate. For example, poly(p-amino styrene) and poly(p-hydroxy carbonyl styrene) can be coated on to PDMS-ox, and be used as acidic and basic surfaces, respectively, to study the acid-base interactions. (2) Another approach is to graft acidic or basic macromers onto a weakly crosslinked polyisoprene or polybutadiene elastomeric networks, and use these elastomeric networks in the JKR studies as described in Section 4.2.1. 

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