We have obtained the 470 MHz 19F NMR spectra of wild type [4-F]Trp-labeled myoglobins (MbCO, MbO2, deoxyMb, metMb, and MbCN) and hemoglobins (HbCO, HbO2, and deoxyHb), as well as those of several mutants (W7F Mb, betaW15F Hb, betaW37S Hb, and betaY130F Hb, all as the carbonmonoxy adducts), prepared via site-directed mutagenesis. The maximum observed chemical shift range induced by folding is 6....

The downfield shift of the NMR signal of the bridging proton in a H-bond (HB) is composed of two elements. The formation of the HB causes charge transfer and polarization that lead to a deshielding. A second factor is the mere presence of the proton-accepting group, whose electron density and response to an external magnetic field induce effects at the position of the bridging proton, exclusive...

From the high-resolution L9F NMR spectrum of single crystal S}W-C6C13F3 its chemical shift shielding tensor is determined. The most shielded direction lies perpendicular to the molecular plane and the least shielded one in the molecular plane perpendicular to the C-F bond. The most (CT33) and least (an) shielded components change significantly in going from 5vw-C6H3F3 and JJW-C6C13F3 to C6F6 wh...

Nuclear spin relaxation provides detailed dynamical information on molecular systems and materials. Here, first-principles modeling of the chemical shift anisotropy (CSA) relaxation time for the prototypic monoatomic (129)Xe gas is carried out, both complementing and predicting the results of NMR measurements. Our approach is based on molecular dynamics simulations combined with pre-parametrize...

This work investigates the nature of second order effects resulting in solid state nuclear magnetic resonance ~NMR!, from cross-correlations between the quadrupolar and shielding couplings. Using an average Hamiltonian theory, it is shown that these effects can bring the nonsecular terms of the shielding interaction into the realm of conventional detection. Such terms include the antisymmetric ...

A recently developed methodology for calculating, analyzing, and visualizing nuclear magnetic shielding densities is used studying spatial contributions including ring-current to 1H resonance (NMR) chemical shifts of aromatic anti-aromatic free-base porphyrinoids. Our approach allows a visual inspection the origin positive (shielding) negative (deshielding) constants. Diatropic paratropic curre...

Quantum chemical methods now permit the prediction of many spectroscopic observables in proteins and related model systems, in addition to electrostatic properties, which are found to be in excellent accord with those determined from experiment. I discuss the developments over the past decade in these areas, including predictions of nuclear magnetic resonance chemical shifts, chemical shielding...