UV Resonance Raman Determination of Polyproline II, Extended 2.5₁-Helix, and β-Sheet Ψ Angle Energy Landscape in Poly-l-Lysine and Poly-l-Glutamic Acid

Citations Over TimeTop 10% of 2005 papers

Abstract

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-alpha-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 2.5(1)-helical conformation, which is an extended beta-strand-like conformation with Psi approximately +170 degrees and Phi approximately -130 degrees . Both of these conformations are highly exposed to water. The energies of these conformations are very similar. We see no evidence of any disordered "random coil" states. In addition, we find that a PLL and PGA mixture at neutral pH is approximately 60% beta-sheet and contains PPII and extended 2.5(1)-helix conformations. The beta-sheet conformation shows little evidence of amide backbone hydrogen bonding to water. We also developed a method to estimate the distribution of Psi Ramachandran angles for these conformations, which we used to estimate a Psi Ramachandran angle energy landscape. We believe that these are the first experimental studies to give direct information on protein and peptide energy landscapes.

Related Papers

• → UV Raman Demonstrates that α-Helical Polyalanine Peptides Melt to Polyproline II Conformations(2004)127 cited
• → UV Resonance Raman Determination of Polyproline II, Extended 2.5₁-Helix, and β-Sheet Ψ Angle Energy Landscape in Poly-l-Lysine and Poly-l-Glutamic Acid(2005)117 cited
• → The alanine-rich XAO peptide adopts a heterogeneous population, including turn-like and polyproline II conformations(2007)69 cited
• → Systematic conformational investigations of peptoids and peptoid–peptide chimeras(2011)27 cited
• → Exploring the Effects on the Conformational Propensity of Alanine in the Unblocked Tripeptide Glycyl-Analyl-Glycine in Water/Ethanol Mixtures(2017)