Alanine acid-base properties

The electron impact mass spectra of 29 oxazolidines derived from sugars, such as 71, have been recorded. Potentiometry has been used to study the acid-base and metal ion complexing properties of 2-benzylamino-2-deoxy-D-g/ycero-D-to/o-heptonic acid in aqueous solution. Complexation was similar to that seen with alanine and the D-g/ycero-D-g /o-analogue, with bodi... 

An interesting approach to obtain peptides in which the purine or pyrimidine residues were correctiy spaced for interaction with the nucleic acids, was made by using a spacer amino acid [49]. Serine was used as a spacer and several protected tetrapeptides, e.g., a-N-t-BOC-L-seryl-D,L-P-(thymin-l-yl)ala-nyl-L-seryl-D,L-P-(thymin-l-yl)alanine, ethyl ester, were synthesized but little was reported about their solution properties and interactions with the nucleic acids. The polymerization of the nucleic acid base-substituted L-lysine derivatives by N-carboxyamino acid anhydride method was also reported [52, 53]. 

Based on the properties of the side chains, the 20 amino acids can be put into six general classes. The first class contains amino acids whose side chains are aliphatic, and is usually considered to include glycine, alanine, valine, leucine, and isoleucine. The second class is composed of the amino acids with polar, nonionic side chains, and includes serine, threonine, cysteine, and methionine. The cyclic amino acid proline (actually, an imino acid) constitutes a third class by itself. The fourth class contains amino acids with aromatic side chains tyrosine, phenylalanine, and tryptophan. The fifth class has basic groups on the side chains and is made up of the three amino acids lysine, arginine, and histidine. The sixth class is composed of the acidic amino acids and their amides aspartate and asparagine, and glutamate and glutamine. 

The 2-D TLC was successfully applied to the separation of amino acids as early as the beginning of thin-layer chromatography. Separation efficiency is, by far, best with chloroform-methanol-17% ammonium hydroxide (40 40 20, v/v), n-butanol-glacial acetic acid-water (80 20 20, v/v) in combination with phenol-water (75 25, g/g). A novel 2-D TLC method has been elaborated and found suitable for the chromatographic identification of 52 amino acids. This method is based on three 2-D TLC developments on cellulose (CMN 300 50 p) using the same solvent system 1 for the first dimension and three different systems (11-IV) of suitable properties for the second dimension. System 1 n-butanol-acetone -diethylamine-water (10 10 2 5, v/v) system 11 2-propanol-formic acid-water (40 2 10, v/v) system 111 iec-butanol-methyl ethyl ketone-dicyclohexylamine-water (10 10 2 5, v/v) and system IV phenol-water (75 25, g/g) (h- 7.5 mg Na-cyanide) with 3% ammonia. With this technique, all amino acids can be differentiated and characterized by their fixed positions and also by some color reactions. Moreover, the relative merits of cellulose and silica gel are discussed in relation to separation efficiency, reproducibility, and detection sensitivity. Two-dimensional TLC separation of a performic acid oxidized mixture of 20 protein amino acids plus p-alanine and y-amino-n-butyric acid was performed in the first direction with chloroform-methanol-ammonia (17%) (40 40 20, v/v) and in the second direction with phenol-water (75 25, g/g). Detection was performed via ninhydrin reagent spray. 

The main aspects of the proposed mechanism have been confirmed by showing that the same Schiff base chelate is formed in solution when either copper(II) or nickel(II) ions are treated with either pyridoxal and alanine or pyridoxamine and pyruvic acid (75), and also by a study of the properties of the strongly fluorescent pyridoxal-alanine-aluminum Schiff base chelate (80). 

The reactions of the Cu(II), Fe(III), and Al(III) chelates of Schiff bases formed by the condensation of pyridoxal with amino acids and peptides were found by Snell to have catalytic properties similar to those of the pyridoxal phosphate enzymes. A typical metal-catalyzed reaction of this type would be the transamination of pyridoxal and alanine according to... 

The method employed in ESR dosimetry is based on the fact that the free radicals formed by irradiation of organic and inorganic solid substances can be stable up to several years as for instance in the L-a-alanine amino acid. To be suitable for ESR dosimetry several additional properties are desirable [4] ... 

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