Diffusion Coefficients of Biomolecules Using Long-Lived Spin States

We report the first observation of long-lived states (LLS) having lifetimes TLLS that exceed the corresponding spin−lattice relaxation times T1 by more than a factor 6 in a protein. Slow diffusion coefficients characteristic of large biomolecules can be determined by combining LLS methods with moderate pulsed field gradients (PFGs) available on commercial probeheads, as the extension of spin memory reduces the strain on the duration and/or strength of the PFGs. No isotope labeling of the biomolecule is necessary.