Assembly of triple-stranded beta-sheet peptides at interfaces.
A 30-residue peptide, BS30, which incorporates two proline residues to induce reverse turns, was designed to form a triple-stranded beta-sheet monolayer at the air-water interface. To discern the structural role of proline, a second peptide, BS30G, identical to BS30 but with glycine residues replacing proline, was prepared and examined in parallel fashion. Surface pressure-molecular area isotherms indicated a limiting area per molecule (ca. 460 A(2)) for BS30 that corresponds well to that estimated from the known dimensions of crystalline beta-sheet monolayers (492 A(2)). Comparable measurements on BS30G yielded a smaller molecular area (380 A(2)). Grazing incidence X-ray diffraction measurements performed on the BS30 monolayer at nominal area per molecule of 500 A(2), exhibited two Bragg peaks corresponding to 4.79 and 34.9 A spacings, consistent with formation of triple-stranded beta-sheet structures that assemble into two-dimensional crystallites at the air-water interface. Visualized by Brewster angle microscopy, BS30 monolayers displayed uniform, solidlike domains, whereas BS30G appeared to be disordered.
Rapaport
Hanna
H
Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena 91125, USA.
Möller
Gunter
G
Knobler
Charles M
CM
Jensen
Torben R
TR
Kjaer
Kristian
K
Leiserowitz
Leslie
L
Tirrell
David A
DA
D010455:Peptides / Q000737:chemistry*; D011487:Protein Conformation; D014961:X-Ray Diffraction
D010455:Peptides