Detecting local heterogeneity and ionization ability in the head group region of different lipidic phases using modified fluorescent probes.
Local heterogeneity in lipid self-assembly is important for executing the cellular membrane functions. In this work, we chemically modified 2-(2'-hydroxyphenyl)benzoxazole (HBO) and attached a C8 alkyl chain in two different locations to probe the microscopic environment of four lipidic phases of dodecyl β-maltoside. The fluorescence change in HBO and the new probes (HBO-1 and HBO-2) shows that in all phases (micellar, hexagonal, cubic and lamellar) three HBO tautomeric species (solvated syn-enol, anionic, and closed syn-keto) are stable. The formation of multi tautomers reflects the heterogeneity of the lipidic phases. The results indicate that HBO and HBO-1 reside in a similar location within the head group region, whereas HBO-2 is slightly pushed away from the sugar-dominated area. The stability of the solvated syn-enol tautomer is due to the formation of a hydrogen bond between the OH group of the HBO moiety and an adjacent oxygen atom of a sugar unit. The detected HBO anions was proposed to be a consequence of this solvation effect where a hydrogen ion abstraction by the sugar units is enhanced. Our results point to a degree of local heterogeneity and ionization ability in the head group region as a consequence of the sugar amphoterism.
Department of Chemistry, Faculty of Science, Sultan Qaboos University, P.O. Box 36, Postal Code 123, Muscat, Sultanate of Oman.
Osama K
OK
Abou-Zied
Department of Chemistry, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia.
N Idayu
NI
Zahid
Department of Chemistry, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia.
M Faisal
MF
Khyasudeen
Glycoteam GmbH, Martin-Luther-King-Platz 6, D-20146 Hamburg, Germany.
David S
DS
Giera
Glycoteam GmbH, Martin-Luther-King-Platz 6, D-20146 Hamburg, Germany.
Julian C
JC
Thimm
Department of Chemistry, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia.
Rauzah
R
Hashim
D000838:Anions / Q000737:chemistry; D001583:Benzoxazoles / Q000737:chemistry; D005456:Fluorescent Dyes / Q000737:chemistry*; D008055:Lipids / Q000737:chemistry*; D008956:Models, Chemical; D015394:Molecular Structure; D012996:Solutions; D012997:Solvents
C433838:2-(2'-hydroxyphenyl)benzoxazole; D000838:Anions; D001583:Benzoxazoles; D005456:Fluorescent Dyes; D008055:Lipids; D012996:Solutions; D012997:Solvents