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Self-Assembled α-Helical Polypeptide Films

Published online by Cambridge University Press:  21 February 2011

Erwin P. Enriquez
Affiliation:
Department of Chemistry, University of North Carolina, Chapel Hill, NC 27599-3290
Edward T. Samulski
Affiliation:
Department of Chemistry, University of North Carolina, Chapel Hill, NC 27599-3290
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Abstract

Poly(γ-benzyl-L-glutamate) (PBLG) derivatized at its N-terminus with lipoic acid, a disulfide-containing moiety, self-assembles on gold from helicogenic solvents to give a thin film with the polypeptide α-helices orientation distribution different from the planar orientation in the unlabeled, physisorbed PBLG films (control) and Langmuir-Blodgett monolayers. The SA films were studied by angle-dependent XPS, reflection-absorption FTIR spectroscopy, and ellipsometry. The IR dichroic properties of the amide I and amide II bands were used to infer the orientational distribution of the helices in the self-assembled film and lead to two extreme pictures of the helix axis distribution function: (a) random (hemispherical distribution) and (b) perfect order with a tilt of 53° from the surface normal. Additional characterization is necessary to differentiate between these two distributions.

Type
Research Article
Copyright
Copyright © Materials Research Society 1992

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