[en] Several basic experimental analytical NMR techniques that are frequently used for the qualitative and quantitative analysis of dynamic and exchange processes, focusing on proteins systems, are described: chemical exchange (slow exchange, fast exchange, intermediate exchange), heteronuclear relaxation measurements (relaxation parameters, strategy of relaxation data analysis, experimental results and examples, motional model interpretation of relaxation data, homonuclear relaxation); slow large-scale exchange and hydrogen-deuterium exchange are also studied: mechanisms of hydrogen exchange in a native protein, methods for measuring amide exchange rates by NMR, interpretation of amide exchange rates. 9 fig., 3 tab., 56 ref

[en] Published in summary form only

[en] Protein G is a member of a class of cell surface bacterial proteins from Streptococcus that bind IgG with high affinity. A fragment of molecular mass 6,988, which retains IgG-binding activity, has been generated by proteolytic digestion and analyzed by ¹H NMR. Two-dimenstional DQF-COSY, TOCSY, and NOESY spectra have been employed to assign the ¹H NMR spectrum of the peptide. Elements of regular secondary structure have been identified by using nuclear Overhauser enhancement, coupling constant, and amide proton exchange data. The secondary structure consists of a central α-helix (Ala28-Val44), flanked by two portions of β-sheet (Val5-Val26 and Asp45-Lys62). This is a fundamentally different arrangement of secondary structure from that of protein A, which is made up of three consecutive α-helics in free solution. The authors conclude that the molecular mechanisms underlying the association of protein A and protein G with IgG are different