Backbone Dynamics and Structures in the Interfacial Domains of Bacteriorhodopsin from Purple Membrane

BACKBONE DYNAMICS AND STRUCTURES IN THE INTERFACIAL DOMAINS OF BACTERIORHODOPSIN FROM PURPLE MEMBRANE 

Site-directed suppression of C NMR signals by slow motional fluctuations 

Theoretically, the expected NMR linewidth I/tiT 2, under CP-MAS or DD-MAS NMR conditions, depends strongly on either the coherent frequency of the proton decoupling or the magic angle spinning, when they interfere with the frequency of the corresponding incoherent random fluctuation motion, if any. In such cases, the overall relaxation rate 1/J2 can be dominantly determined by the following second or third terms instead of the first term of the static component by 

B/and cos are the gyromagnetic ratios of the I and S nuclei, respectively, and r is the intemuclear distance between the spins I and S. (Og and (Oj are the carbon resonance frequency and the amplitude of the proton decoupling RF field, respectively. (Or is the rate of spinner rotation, b the chemical shift anisotropy and rj the asymmetric parameter of the chemical shift tensor. 

Experimentally, it is possible to evaluate a relative contribution of the NMR signals (j) from residues located at the surface areas by comparing their peak intensities in the presence (7) with those in the absence of 40 pM Mn ion (/q) (as discussed in Section 3.4) as 

---

Backbone Dynamics and Structures in the Interfacial Domains of Bacteriorhodopsin from Purple Membrane... 

---