Phenyl-Ring Dynamics in Amyloid Fibrils and Proteins: The Microscopic-Order-Macroscopic-Disorder Perspective
| Autor: | Zhichun Liang, Eva Meirovitch, Jack H. Freed |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2018 |
| Předmět: |
Models
Molecular Magnetic Resonance Spectroscopy Globular protein Protein Conformation Motion (geometry) 010402 general chemistry 01 natural sciences Article Protein structure Protein Domains Neurofilament Proteins Materials Chemistry Physical and Theoretical Chemistry chemistry.chemical_classification Physics Amyloid beta-Peptides 010405 organic chemistry Dynamics (mechanics) Atmospheric temperature range Deuterium Peptide Fragments 0104 chemical sciences Surfaces Coatings and Films Order (biology) chemistry Models Chemical Chemical physics Crystallite |
| Popis: | We have developed the microscopic-order-macroscopic-disorder (MOMD) approach for studying internal mobility in polycrystalline proteins with 2H lineshape analysis. The motion itself is expressed by a diffusion tensor, R, the local spatial restraints by a potential, u, and the "local geometry" by the relative orientation of the model-related and nuclear magnetic resonance-related tensors. Here, we apply MOMD to phenyl-ring dynamics in several Αβ40-amyloid-fibrils, and the villin headpiece subdomain (HP36). Because the available data are limited in extent and sensitivity, we adjust u and R in the relevant parameter ranges, fixing the "local geometry" in accordance with standard stereochemistry. This yields a physically well-defined and consistent picture of phenyl-ring dynamics, enabling comparison between different systems. In the temperature range of 278-308 K, u has a strength of (1.7-1.8) kT and a rhombicity of (2.4-2.6) kT, and R has components of 5.0 × 102 ≤ R⊥ ≤ 2.0 × 103 s-1 and 6.3 × 105 ≤ R∥ ≤ 2.0 × 106 s-1. At 278 K, fibril hydration increases the axiality of both u and R; HP36 hydration has a similar effect at 295 K, reducing R⊥ considerably. The D23N mutation slows down the motion of the probe; Aβ40 polymorphism affects both this motion and the related local potential. The present study identifies the impact of various factors on phenyl-ring mobility in amyloid fibrils and globular proteins; the difference between the two protein forms is considerable. The distinctive impact of hydration on phenyl-ring motion and previously studied methyl-group motion is also examined. The 2H lineshapes considered here were analyzed previously with various multi-simple-mode (MSM) models, where several simple motional modes are combined. The MOMD and MSM interpretations differ in essence. |
| Databáze: | OpenAIRE |
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