New developments in nuclear magnetic resonance (NMR) relaxation spectr
oscopy and the availability of isotopically labeled biomolecules led t
o significant progress in the understanding of polypeptide dynamics in
solution. This article summarizes some of the author's work on homonu
clear and heteronuclear NMR relaxation of peptides and proteins and th
eir structural dynamical interpretation based on a variety of differen
t methods.