ISSN:
1434-4475
Keywords:
Phytochrome models
;
2,3-Dihydrobilatrienes-abc
;
Hexamethylphosphoric acid triamide
;
Stretched chromophore-conformation
;
NMR-techniques
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract Using hexamethylphosphoric acid triamide (HMPT) as solvent for bilatrienesabc and mainly for 2,3-dihydrobilatrienes-abc (which serve as the most suitable models for the biliproteid chromophores) a small hypsochromic shift and a dramatic change of the relative intensities of short and long wavelength absorption bands, as compared to solutions in CCl4, is observed. Applying NMR-spectroscopic techniques (15N-,13C-,1H-) a predominance of the (4Z,9E,15Z) diastereomer forming a 5syn-, 10anti-, 14syn-periplanar orclinal conformation is deduced. The stabilisation of this configuration and conformation arises from strong hydrogen bonds between the acidic protons of the bilins andHMPT. Interactions of this kind seem to be the main source of energy to stretch the otherwise coiled bilin chromophore of (4Z,9Z,15Z)-5sp,10sp,14sp geometry. Stretched systems of the type bilin-HMPT may serve as a valuable model for the natural biliproteides.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00809199
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