2-Amino-2-methylbutyric acid

Dialkylamino acids, C -dialkylamino acids, amino acids bearing two alkyl substituents at the a-carbon atom. Examples are the naturally occurring amino acids diethylglycine (Deg), a-aminoisobutyric acid (Aib), or isovaline (Iva, 2-amino-2-methylbutyric acid). Such amino acids are often incorporated into peptides to study the conformational requirements of receptors, and are used as building blocks for the stabilization of short peptides in a well-defined conformation, depending on the nature of the two substituents attached to the C -carbon. 3io-Hdices are stabilized by the incorporation of Aib and other C -dialkyl-substituted building blocks [P. Balaram, T. S. Sudha, Int.J. Pept. Protein Res. 1983, 21, 381 I. L. Karle, Biopolymers 1996, 40,157 B. Pispisa et al.. Biopolymers 2000, 53,169]. 

Methyl-l-nitrobutane, A"33.8 Valine, A4.19, A"15 Norvaline, A10.15, A"8 2-Amino-2-methylbutyric acid, A40.9 4-Amino-2-methylbutyric acid, A34.5 4-Amino-3-methylbutyric acid, A27.16 4-Aminopentanoic acid, A 14.14, A"6, A"8 [4- C]Valine, D 3.10... 

Acrylic acid chloride 9185 />-Aminoacetophenone 398 2-Amino-2-methylbutyric acid 6558... 

At high pH (> 10-11) saponification of the sulfonyl chloride to the sodium salt of 3-amino-3-methylbutyric acid-N-sulfonic acid will predominate, and at too low a pH (e.g., pH of 0) hydrolysis to 3-hydroxy-3-methylbutyramide will prevail. 

L-2-Amino-3-hydroxypropanoic Acid, 50 L-2-Amino-3-methylbutyric Acid, 62 DL-2-Amino-3-methylvaleric Acid, 30 DL-2-Amino-4-methylvaleric Acid, 32 L-2-Amino-3-methylvaleric Acid, 31... 

L-a-Amino-4(or 5)-imidazolepropionic Acid Monohydrochloride, 193 DL-a-Amino-3-indolepropionic Acid, 426 L-a-Amino-3-indolepropionic Acid, 427 L-2-Amino-3-mercaptopropanoic Acid Monohydrochloride, 113 L-2-Amino-3-methylbutyric Acid, 429, (S3)62... 

Sewage Sludge Strain. The sludge strain PS of M. ruminantium is similar nutritionally to the rumen strain but is less exacting in its requirements and can be grown easily in a chemically defined medium—i.e., the medium shown in Table II but with 3.8 mM (NH4)2S04 added and with rumen fiuid and volatile acids other than acetate deleted. This strain does not require 2-methylbutyric acid, amino acids, or the unidentified factor required by the rumen strain. In fact, it biosynthesizes this growth factor. However, it does require acetate and ammonia. 

Furthermore, Sato and Ikekawa (238) have obtained by chromic acid oxidation of (257 )-22,26-acetylepimino-3/3,16(8-diacetoxycholesta-5,22-diene (LX), prepared from solasodine (I) by acetylation (238, 239), 16 -hydroxy-3(8-acetoxy-22,23-bisnorchol-5-enic lactone (acetyldios-genin lactone, LXI). The side chain fragment of this degradation, which involves the carbon atoms 23-27 including the center of chirality C-26, has been identified as (R)-( — )-4-amino-3-methylbutyric acid (LXII) (240), the constitution of which was confirmed by comparison with the synthesized racemic compound. Its absolute configuration was confirmed by conversion into (R)-( +)-methylsuccinic acid (LXIII) (225, 226). 

Branched fatty acids, known as iso-acids and anteiso-acids, occur normally in small quantities in fats. Their synthesis begins with the amino-acids valine and isoleucine (Figure 3.12). This has been demonstrated with radio-labelled isotopes, by radio-active monitoring and with stable isotopes by C nuclear magnetic resonance spectroscopy or mass spectrometry. Both isobutyric acid and 2-methylbutyric acid are common defensive compounds among insects. Note that a chiral centre is introduced in 2-methylbutyric acid and anteiso acids. 

As pointed out earlier, a wide variety of Gram-positive bacteria contain branched-chain acids often these acids comprise more than 50% of the total fatty acids. The similarity of the branched-chain portion of the antiiso and iso acids to the amino acids isoleucine and leucine (Fig. 9) prompted an investigation of the possible role of these compounds in the formation of the branched-chain acids in M. lysodeikticus (Lennarz, 1961). In vivo experiments revealed that isoleucine and a-methylbutyric acid served as specific precursors of the methyl terminal portion of 12-methyltetradecanoic acid. Although carbon atoms 2-6 of isoleucine and 1- of a-methylbutyric acids were incorporated into the branched-chain acid, C-1 of isoleucine was not. On the basis... 

Acetamido-3-methylbutyric acid, A27.16 2-Amino-3-hydroxycyclohexanecarboxylic acid,... 

The hyoscine system occurs alone in certain northern Duboisia myo-poroides, and forms scopine, -tropine, dihydroxytropane and, in Datura meieloides, teloidine. Of these amino-alcohols, all the scopine is esterified by tropic acid and the minor bases by tiglic, methylbutyric or isovaleric acid, which contain the isoprene skeleton and are presumed to arise from that source. 

The reason for the inefiiciency of these bacteria in utilizing amino acids is not definitely known however, it seems probable, as is the case with some of the carbohydrate-fermenting rumen bacteria (8, 33), that these materials are not transported effectively into the cell. It seems probable that, in their adaptation to the natural habitat, their abilities to utihze proteins and amino acids were of little survival value and were lost. It is well known that amino acids are present in very small amounts in extracellular fiuid of rumen contents while relatively high concentrations of ammonia and acetate and other volatile acids including 2-methylbutyrate are present (8). A similar condition probably exists in sludge although the volatile acids are usually present in lower concentration than in the rumen. 

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