Model-Free Approach beyond the Borders of Its Applicability

✍ Scribed by Dmitry M. Korzhnev; Vladislav Yu. Orekhov; Alexander S. Arseniev

• Publisher: Elsevier Science
• Year: 1997
• Tongue: English
• Weight: 177 KB
• Volume: 127
• Category: Article
• ISSN: 1090-7807
• DOI: 10.1006/jmre.1997.1190

✦ Synopsis

Model calculations presented in this article show that commonly behavior of the system under consideration. The simplest used methodology of 15 N relaxation data analysis completely fails form of the spectral density function (1) assumes isotropic in detecting nanosecond time scale motions if the major part of molecular rotational tumbling and fast internal motions with the molecule is involved in these motions. New criteria are introcharacteristic times shorter than 100 ps. The alternative and duced for the detection of such cases, based on the dependence of more complicated models account also for the possible anthe apparent overall correlation time, derived from the T 1 /T 2 ratio, isotropy of the overall molecular rotational diffusion ( 7) or on the spectrometer frequency. Correctly estimating the overall for slow internal motions (3). As was shown in our previous rotation correlation time t R was shown to play the key role in work (8), the same relaxation data can satisfactorily fit the model-free data analysis. It is found, however, that in cases of simple (1, 2) and extended (3) forms of the spectral density slow internal motions with characteristic times of more than 3-4 function, leading to qualitatively different pictures of the ns, the effective t R provided by the T 1 /T 2 ratio for individual amide nitrogens can be used for the characterization of the fast protein internal dynamics. In the latter case, the lower order picosecond internal dynamics. ᭧ 1997 Academic Press parameters and longer overall rotational correlation times are observed.