UV Resonance Raman and Absorption Studies of Angiotensin II Conformation in Lipid Environments
نویسنده
چکیده
We have used UV resonance Raman and absorption spectroscopy to examine the secondary structure of angiotensin 11 ( AII) in aqueous solution and in phospholipid micelles. Absorption difference spectroscopic measurements are used to determine the association constant of A11 with dodecylphosphocholine (DPC) micelles, and the UV Raman spectral data are used to examine the secondary structure alterations which occur upon A11 partitioning into the DPC micelles. The 208 nm excited amide I11 peptide bands give information on the peptide backbone conformation. A11 appears to exist in several conformers such as @-sheet, irregular, and turnlike structure in aqueous solution, while it adopts a more highly ordered 0-turn structure in DPC micelles. The Tyr and Phe absorption and Raman excitation profile redshifts upon A11 binding to DPC micelles indicate that the Tyr and Phe side chains of AII, which are exposed to water in aqueous solution, partition into the hydrophobic core of the lipid DPC micelles.
منابع مشابه
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 cha...
متن کاملUV Resonance Raman Determination of Polyproline II, Extended 2.51-Helix, and -Sheet Ψ Angle Energy Landscape in Poly-L-Lysine and Poly-L-Glutamic Acid
UV resonance Raman (UVR) spectroscopy was used to examine the solution conformation of poly-L-lysine (PLL) and poly-L-glutamic acid (PGA) in their non-R-helical states. UVR measurements indicate that PLL (at pH ) 2) and PGA (at pH ) 9) exist mainly in a mixture of polyproline II (PPII) and a novel left-handed 2.51-helical conformation, which is an extended -strand-like conformation with Ψ ≈ +17...
متن کاملDihedral psi angle dependence of the amide III vibration: a uniquely sensitive UV resonance Raman secondary structural probe.
UV resonance Raman studies of peptide and protein secondary structure demonstrate an extraordinary sensitivity of the amide III (Am III) vibration and the C(alpha)H bending vibration to the amide backbone conformation. We demonstrate that this sensitivity results from a Ramachandran dihedral psi angle dependent coupling of the amide N-H motion to (C)C(alpha)H motion, which results in a psi depe...
متن کاملUV resonance Raman investigation of the conformations and lowest energy allowed electronic excited states of tri- and tetraalanine: charge transfer transitions.
UV resonance Raman excitation profiles and Raman depolarization ratios were measured for trialanine and tetraalanine between 198 and 210 nm. Excitation within the pi --> pi* electronic transitions of the peptide bond results in UVRR spectra dominated by amide peptide bond vibrations. In addition to the resonance enhancement of the normal amide vibrations, we find enhancement of the symmetric te...
متن کاملUV resonance Raman-selective amide vibrational enhancement: quantitative methodology for determining protein secondary structure.
We have directly determined the amide band resonance Raman spectra of the "average" pure alpha-helix, beta-sheet, and unordered secondary structures by exciting within the amide pi-->pi* transitions at 206.5 nm. The Raman spectra are dominated by the amide bands of the peptide backbone. We have empirically determined the average pure alpha-helix, beta-sheet, and unordered resonance Raman spectr...
متن کامل