Circular dichroism spectroscopic study of non-covalent interactions of poly-L-glutamic acid with a porphyrin derivative in aqueous solutions.
The interactions of poly-L-glutamic acid and a cationic porphyrin derivative in aqueous solutions were studied by the combination of vibrational circular dichroism (VCD) and electronic circular dichroism (ECD) spectroscopies. It was found that non-covalent interactions between both agents influence the structure of the polymeric matrix and the guest porphyrins and vice versa, but the physico-chemical properties of the solutions, especially the pH and the relative permittivity of the solvent, play a key role in the structure of the polypeptide part of the formed complexes. It was shown that the interaction with porphyrins prevents the precipitation of poly-L-glutamic acid in aqueous solution at acidic pH. In special conditions, the porphyrins attached to the polypeptide probably possess face-to-face interaction as demonstrated by the enhancement of the characteristic ECD signal and the appearance of sidebands on its short and long wavelength sides.
Palivec
Lukás
L
Department of Analytical Chemistry, Institute of Chemical Technology, Technická 5, 166 28 Praha 6, Czech Republic.
Urbanová
Marie
M
Volka
Karel
K
D002942:Circular Dichroism; D015394:Molecular Structure; D011099:Polyglutamic Acid / Q000737:chemistry*; D011166:Porphyrins / Q000737:chemistry*; D012996:Solutions; D013056:Spectrophotometry, Ultraviolet; D014867:Water / Q000737:chemistry
D011166:Porphyrins; D012996:Solutions; D014867:Water; D011099:Polyglutamic Acid