PROTEIN PHYSICSPROTEIN PHYSICS

LECTURE 7LECTURE 7

Main secondary structuresMain secondary structures

Helices: Helices: Right and LeftRight and Left

H-bondsH-bonds

Mirror-asymmetric amino acids – Mirror-asymmetric amino acids – mirror-asymmetric (“chiral”) helicesmirror-asymmetric (“chiral”) helices

Right Right -helix-helix

RightRight-helix-helix

Right Right -helix-helix

Right 3Right 310 10 helixhelix

ALA, etc. GLY onlyALA, etc. GLY only

,,twistedtwisted

,,twistedtwisted

Mirror-asymmetric Mirror-asymmetric amino acids – amino acids –

mirror-asymmetric mirror-asymmetric twist of twist of -sheets-sheets

-hairpin with turn-hairpin with turn

turn Iturn I

turn I’turn I’

turn IIturn II

-bulge-bulge

collagen triple helixcollagen triple helix

NMRNMRspectroscopyspectroscopy(cross-peaks)(cross-peaks)

ExperimentalExperimentalstudy of study of

secondary secondary structurestructure

X-ray X-ray crystallographycrystallography

Far UV CD spectraFar UV CD spectra(peptide groups)(peptide groups)

IR spectraIR spectra(amid I, C=O bond)(amid I, C=O bond)

Experimental study of secondary structureExperimental study of secondary structure

GlobularGlobular

FibrousFibrous

H-bondsH-bonds & & hydrophobicshydrophobics

MembraneMembrane