RECOGNITION OF SECONDARY-STRUCTURE ELEMENTS IN 3D TOCSY-NOESY SPECTRA OF PROTEINS - INTERPRETATION OF 3D CROSS-PEAK AMPLITUDES

The amplitudes of selected 3D cross peaks in 3D TOCSY-NOESY spectra of proteins are shown to be characteristically different depending on the secondary structure. The sets of 3D cross peaks which make up the pattern for tight turns, β sheets, and α helices are given together with an estimate of the integral amplitude for each of the cross peaks obtained by a series development of the Hamiltonian of lowest order. A 3D TOCSY-NOESY spectrum of BPTI with a comparably short TOCSY mixing time was recorded and the volume integrals of the 3D cross peaks relevant for the recognition of the secondary-structure elements were compared to the amplitudes expected from a lowest order approximation. © 1990.