UV resonance Raman study of angiotensin II conformation in nonaqueous environments: lipid micelles and acetonitrile.
We used 206.5-nm excited resonance Raman measurements to examine the angiotensin II (AII) secondary structure in H(2)O in the presence of dodecylphosphocholine (DPC) micelles, sodium dodecylsulfate (SDS) monomers and micelles, and in a 70% acetonitrile (ACN-d)-30% water solution. Our AII-SDS titration absorption studies indicate the formation of a 1:2 AII:SDS complex in which two negatively charged SDS molecules attach to the AII positively charged N terminus and to Arg(2). Our 206.5-nm excited Raman results indicate that the 1:2 AII:SDS complexation increases the AII beta-turn composition. We also used 228.9-nm Raman excitation to probe the local solvent accessibility of Tyr(4) (AII) in DPC and SDS micelles. Our Tyr (AII) solvent accessibility studies suggest that the Tyr residue is more exposed to the aqueous environment in SDS micelles than in DPC micelles.
Holtz
J S
JS
Department of Chemistry, Chevron Science Center, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA.
Lednev
I K
IK
Asher
S A
SA
D000097:Acetonitriles / Q000494:pharmacology; D000804:Angiotensin II / Q000737:chemistry* / Q000528:radiation effects; D000818:Animals; D006801:Humans; D008055:Lipids / Q000737:chemistry / Q000494:pharmacology; D008567:Membranes, Artificial; D008823:Micelles; D010767:Phosphorylcholine / Q000031:analogs & derivatives / Q000737:chemistry / Q000494:pharmacology; D011487:Protein Conformation / Q000187:drug effects; D017433:Protein Structure, Secondary / Q000187:drug effects*; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry / Q000494:pharmacology; D012997:Solvents / Q000494:pharmacology*; D013059:Spectrum Analysis, Raman / Q000379:methods; D014466:Ultraviolet Rays; D014867:Water / Q000494:pharmacology
D000097:Acetonitriles; D008055:Lipids; D008567:Membranes, Artificial; D008823:Micelles; D012997:Solvents; D014867:Water; D010767:Phosphorylcholine; D000804:Angiotensin II; D012967:Sodium Dodecyl Sulfate; C028810:dodecylphosphocholine; C032159:acetonitrile