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Solid-State NMR Structural Studies of Peptides Immobilized on Gold Nanoparticles

2005; American Chemical Society; Volume: 21; Issue: 7 Linguagem: Inglês

10.1021/la040092w

1520-5827

P.V. Bower, Elizabeth A. Louie, Joanna Long, Patrick S. Stayton, Gary P. Drobny,

Advanced biosensing and bioanalysis techniques

In this paper we describe solid-state NMR experiments that provide information on the structures of surface-immobilized peptides. The peptides are covalently bound to alkanethiolates that are self-assembled as monolayers on colloidal gold nanoparticles. The secondary structure of the immobilized peptides was characterized by quantifying the Ramachandran angles φ and ψ. These angles were determined in turn from distances between backbone carbonyl 13C spins, measured with the double-quantum filtered dipolar recoupling with a windowless sequence experiment, and by determination of the mutual orientation of chemical shift anisotropy tensors of 13C carbonyl spins on adjacent peptide planes, obtained from the double-quantum cross-polarization magic-angle spinning spectrum. It was found that peptides composed of periodic sequences of leucines and lysines were bound along the length of the peptide sequence and displayed a tight α-helical secondary structure on the gold nanoparticles. These results are compared to similar studies of peptides immobilized on hydrophobic surfaces.