Polydepsipeptides. 5. Experimental Conformational Analysis of Poly(L-alanyl-L-lactic acid) and Related Model Compounds
| Autor: | R. T. Ingwall, Murray Goodman, C. Gilon |
|---|---|
| Rok vydání: | 1976 |
| Předmět: |
Alanine
Depsipeptide Circular dichroism Magnetic Resonance Spectroscopy Chloroform Spectrophotometry Infrared Polymers and Plastics Protein Conformation Hydrogen bond Stereochemistry Circular Dichroism Organic Chemistry Molecular Conformation Nuclear magnetic resonance spectroscopy Lactic acid Inorganic Chemistry chemistry.chemical_compound Crystallography chemistry Intramolecular force Lactates Materials Chemistry Spectrophotometry Ultraviolet Peptides |
| Zdroj: | Macromolecules. 9:802-808 |
| ISSN: | 1520-5835 0024-9297 |
| DOI: | 10.1021/ma60053a022 |
| Popis: | In this paper we report an experimental conformational analysis of the depsipeptide model compounds acetyl-L-alanine methyl ester, acetyl-L-lactic acid N-methylamide, and acetyl-L-alanyl-L-lactic acid N-methylamide and of the sequential polydepsipeptide poly(L-alanyl-L-lactic acid). The model depsipeptides were examined in dilute organic solutions by infrared and nuclear magnetic resonance spectroscopy. Neither acetyl-L-alanine methyl ester nor acetyl-L-lactic acid N-methylamide assumes an intramolecularly hydrogen-bonded conformation. Acetyl-L-alanyl-L-lactic acid N-methylamide, on the other hand, in dilute chloroform or dilute carbon tetrachloride solutions, strongly favors a conformation with an intramolecular hydrogen bond between the N-H hydrogen atom of its N-methylamide group and the carbonyl oxygen atom of its acetyl group. Comparison of theoretical and experimental circular dichroism suggests that poly(L-alanyl-L-lactic acid) is partially ordered in chloroform solution with approximately 50% of its repeat units in the R10 helix, an ordered conformation found by our previous theoretical analysis to have a low intramolecular conformational energy. |
| Databáze: | OpenAIRE |
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