A Aminoisobutyric acid

Hydroxyl Group. The OH group of cyanohydrins is subject to displacement with other electronegative groups. Cyanohydrins react with ammonia to yield amino nitriles. This is a step in the Strecker synthesis of amino acids. A one-step synthesis of a-amino acids involves treatment of cyanohydrins with ammonia and ammonium carbonate under pressure. Thus acetone cyanohydrin, when heated at 160°C with ammonia and ammonium carbonate for 6 h, gives a-aminoisobutyric acid [62-57-7] in 86% yield (7). Primary and secondary amines can also be used to displace the hydroxyl group to obtain A/-substituted and Ai,A/-disubstituted a-amino nitriles. The Strecker synthesis can also be appHed to aromatic ketones. Similarly, hydrazine reacts with two molecules of cyanohydrin to give the disubstituted hydrazine. 

The analysis of extraterrestrial matter is concentrated on the detection of nucleic acid and protein building blocks, i.e., N-heterocycles and amino acids. The search for such compounds began immediately after the fall of the Murchison meteorite. Twenty-two amino acids were detected in it as early as 1974 eight of them pro-teinogenic, ten which hardly ever occurred in biological material, and four which were unknown in the biosphere. Up to now, about 70 amino acids have been identified (Cronin, 1998), the most common being glycine and a-aminoisobutyric acid. The latter is a branched-chain amino acid with the smallest possible number of carbon atoms. The most frequently found amino acids occur in concentrations of... 

The number of scientific articles published on meteorites has increased dramatically in the last few years few of these, however, concern themselves with small meteorites, the size of which lies between that of the normal meteorites (from centimetres to metres in size) and that of interplanetary dust particles. In the course of an Antarctic expedition, scientists (mainly from French institutions) collected micrometeorites from 100 tons of Antarctic blue ice (Maurette et al 1991). These micrometeorites were only 100 400 pm in size five samples, each consisting of 30-35 particles, were studied to determine the amount of the extraterrestrial amino acids a-aminoisobutyric acid (AIBS) and isovaline—both of which are extremely rare on Earth—which they contained. The analysis was carried out using a well-tested and extremely sensitive HPLC system at the Scripps Institute, La Jolla. Although the micrometeorites came from an extremely clean environment, the samples must have been contaminated, as they all showed traces of L-amino acids. Only one sample showed a significantly higher concentration of AIBS (about 280 ppm). The AIBS/isovaline ratio in the samples also lay considerably above that previously found in CM-chondrites. 

A ngstrom unit (ICE10 m) adenosine diphosphate N-(2-aminoethyl)-glycine a-aminoisobutyric acid residues adenosine monophosphate amidotriphosphate adenosine triphosphate... 

Barone, V., F. Fratemali, and P. L. Cristinziano. 1990. Sensitivity of Peptide Conformation to Methods and Geometrical Parameters. A Comparative Ab Initio and Molecular Mechanics Study of Oligomers of a-Aminoisobutyric Acid. Macromolecules 23, 2038-2044. 

VV Suresh Babu, HN Gopi. Rapid and efficient synthesis of peptide fragments containing a-aminoisobutyric acid using Fmoc-amino acid chlorides/potassium salt of 1-hydroxybenzotriazole. Tetrahedron Lett 39, 1049, 1998. 

Af- 2-(Methoxycarbonyl)benzoylJ-(o -aminoisobutyryl)-a-aminoisobutyric acid A7-[2-(tert-butylperoxy)-2-propyl]amide (AHANUS) 1.436 140.2 162... 

Although long 310 helices are seldom found in proteins, a single turn of this tighter helix frequently occurs as a "defect" at the end of an a helix. A polymer of a-aminoisobutyric acid forms long 310 helices because the a-dimethyl side chains constrain (]) and j/ to appropriate values.145 Short helical peptide... 

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