Efficient analysis of macromolecular rotational diffusion from heteronuclear relaxation data

Area of Science:

• Biophysics
• Structural Biology
• Computational Chemistry

Background:

• Nitrogen-15 (15N) relaxation rates provide insights into macromolecular dynamics.
• Interpreting these rates requires robust models of anisotropic rotational diffusion.
• Accurate modeling is crucial for understanding protein structure and function.

Purpose of the Study:

• To develop a novel computational program for interpreting 15N relaxation data.
• To analyze macromolecular anisotropic rotational diffusion using advanced algorithms.
• To provide statistically validated models of molecular motion.

Main Methods:

• Developed a program utilizing simulated annealing/minimization for efficient parameter space searching.
• Implemented isotropic, axially symmetric, and fully anisotropic rotational diffusion tensor models.
• Performed noise-based Monte Carlo error analysis and applied statistical tests for confidence limits.

Main Results:

• Demonstrated the program's efficiency in analyzing complex diffusion models.
• Successfully applied the program to cytochrome c' from Rhodobacter capsulatus.
• Independently analyzed and compared data from three different field strengths, validating the models.

Conclusions:

• The novel program effectively interprets 15N relaxation rates for anisotropic rotational diffusion.
• The employed algorithm and statistical analyses provide reliable confidence limits for diffusion models.
• This tool enhances the study of protein dynamics and structural biology.