Glutamic acid absorption spectrum

Poly-L-glutamic acid Peptide absorption spectrum from 1900-2400 A is conformation-dependent Imahori and T anaka (1959)... 

Fig. 15. Rotatory artifacts that simulate Cotton effects at an absorption band. The dependence of the rotatory artifact on absorbance of p-cresol solutions placed in series with the same poly-L-glutamic acid solution is shown. The concentration of p-cresol was adjusted to give the total absorbance of chromophore plus polypeptide background that appears with each curve. The rotator, poly-L-glutamic acid, was at concentration of 0.5% at pH 7.0 in a 10-cm cell. The rotations are those actually observed, a, in degrees. The rotatory dispersion at Am 2 coincides almost exactly with that for the polypeptide alone, so that it has been omitted from the figure. At Am 4, an interference filter, /, with maximum transmission between 280 and 285 m/i, was placed in the optical path. The absorption spectrum, in arbitrary units, is typical of p-cresol plus poly-L-glutamic acid background. The emission spectrum is represented in arbitrary units, uncorrected for detector response. (Urnes et al., 1961a.)...

Fig. 16. The appearance of rotatory artifacts both at the minimum in the emission spectrum of the mercury arc and as increasing polypeptide absorption is encountered below 250 m/i. The rotations are those actually observed, a, in degrees, for a 0.6% poly-L-glutamic acid solution at pH 7 in a 10-cm cell. The absorption spectrum of poly-L-glutamic acid and the emission spectrum of the arc, uncorrected for detector response, are in arbitrary units. (Urnes et al., 1961b.)...

Chemically, domoic acid is (25,35,45)-2-carboxy-4-l-methyl-5(R)-carboxyl-l(Z)-3( )-hexadi-enyl pyrrolidine-3-acetic acid (C15H21NO6) and has an anhydrous molecular weight of 311.14, a melting point of 215-216°C (dihydrate), and a UV (ethanol) absorption spectrum with a maximum of 242 nm, although this is pH dependent. Structurally, domoic acid is very similar to another known toxin, kainic acid, and both are analogues of the amino acids glutamate and proline. The structures of domoic and kainic acid are shown in Figure 20.1. 

Figure 5.21. Photo-mechanical and photo-chemical transduction in a model protein that contains a proto-natable glutamic acid residue and a chromophore capable of being driven from trans to cis on absorption of 300 nm light, both existing within the same hydrophobic association domain. (A) Ultraviolet absorption spectra showing the changes in the spectrum on going from 100% trans to 90% cis on illumination with 300 nm light. (B) Light-driven shift of isomer from trans to cis increases the value of T,. (C) Light-driven shift of isomer from trans to cis lowers the pKa of Glu carboxy-late. (From Heimbach. ...

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