Alanine infrared absorption

The teichoic acid shows an infrared absorption band at 1751 cm.-1, characteristic of carboxylic ester groups, which is not observed in samples from which the D-alanine residues have been removed. Removal of the u-alanine was readily effected with ammonia or hydroxylamine, when D-alaninamide or D-alanine hydroxamate were formed. The kinetics of the reaction with hydroxylamine reveal the high reactivity of its D-alanine ester linkages, which, like those in most other teichoic acids, are activated by the presence of a neighboring phosphate group. That the D-alanine residue is attached directly to the ribitol residues, instead of to the d-glucosyl substituents, was also shown by oxidation with periodate under controlled conditions of pH, when it was found that the D-alanine residues protect the ribitol residues from oxidation. Under the same conditions, all of the ribitol residues were oxidized in a sample of teichoic acid from which the D-alanine had been removed, and it is concluded that the ester groups are attached to C-2 or C-3 of the ribitol residues. 

Hatta, A., Moriya, Y., and Suetaka, W. (1975) The infrared absorption spectra of nickel metal surfaee modified with optieally active alanine from its aqueous solution. Bull. Chem. Soc. Jpn. 4 8,3441 - 3445. 

The absorption modes of (S)-3-phenyl-2-hydroxypropionic acid, (S)-3-phenyl-2-aminopropionic acid, and (S)-alanine adsorbed on a nickel plate or RNi were studied by Suetaka s group (71, 72). From the measurement of infrared (IR) dichroism in the reflection spectrum, the molecular orientation of the modifying reagent was deduced. Figures 19-21 show molecular orientations of (S)-2-hydroxy-3-phenylpropionic acid on a nickel plate and (R)-alanines on RNis modified at 5° and 100°C, respectively. 

From the young pea seedlings of Pisum sativum L. var. Rondo there was isolated another pyrimidine amino acid, the structure of which was initially proposed [429] as L- -(5-uracilyl)alanine (LXXVIIIa). However, its physical constants by no means agree with those of the authentic -(5-uracilyl)alanine unequivocally synthesised earlier [430, 431]. The structure has since been revised to L- -(3-uracilyl)alanine (LXXIX, isowillardiine) by examination of its ultraviolet absorption characteristics and chemical reactions [422] and substantiation by infrared, NMR, and mass spectrometry [432]. Its biological role has not yet been determined. 

Chapman and Morrison (1966) have found NMR evidence favoring a dipolar ionic form for the phosphatidyl ethanolamines. Also, their infrared spectra of chloroform solutions favor a dipolar ionic structure. The evidence was as follows if dioleoyl-phosphatidyl ethanolamines exist in chloroform in a nonionic form, then intense bands in the 3300 cm region should occur because of NH stretching frequencies. Bands were found at 3058, 2710, 2538, and a probable band at 3021 cm , which they correlated with vibrations of an NHj group. A comparison of the spectra of dioleoyl-phosphatidyl ethanolamine and a dipolar ionic amino acid, such as alanine, showed almost identical spectra in the 4000 to 2000 cm region. The spectrum of the non-ionized compound, OL-a-alanine methyl ester in chloroform shows intense absorption in the 3300 cm region characteristic of a free primary amino group. 

The first efforts towards real-time and in-line monitoring of CO2 absorption processes focused on the use of Fourier transform infrared (FTIR) spectroscopy in combination with a multivariate model. Geers et al. (3) successfully applied this methodology to a solvent consisting of an equimolar solution of p-alanine and potassium hydroxide. They predicted the concentrations of the amine, of absorbed CO2 and SO2, and also included the effect of NO2 in their analysis. 

Two series of P2 isomers were isolated with glycine, S-alanine, and S-methionine. The complexes all had visible and infrared spectra expected of P2 isomers,but the two series differed in CD spectra. They are interpreted as conformational isomers, as represented in Fig. 3. Thus far, pmr spectra have been inconclusive in distinguishing the conformational isomers. The CD and absorption spectra of the six jS-isomers of [Co(trien)(S-ala)]l2-H20 are compared in Fig. 5. The absorption curves are the same for both jS2 isomers. 

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