Journal Article

FZJ-2021-00905

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Structure and Dynamics of Ribonuclease A during Thermal Unfolding: The Failure of the Zimm Model

Fischer, J. ; Radulescu, A.FZJ* ; Falus, P. ; Richter, D.FZJ* ; Biehl, R. (Corresponding author)FZJ*

2021
Soc. Washington, DC

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Please use a persistent id in citations: http://hdl.handle.net/2128/27137  doi:10.1021/acs.jpcb.0c09476

Abstract: Disordered regions as found in intrinsically disordered proteins (IDP) or during protein folding define response time to stimuli and protein folding times. Neutron spin-echo spectroscopy is a powerful tool to directly access the collective motions of the unfolded chain to enlighten the physical origin of basic conformational relaxation. During the thermal unfolding of native ribonuclease A, we examine the structure and dynamics of the disordered state within a two-state transition model using polymer models, including internal friction, to describe the chain dynamics. The presence of four disulfide bonds alters the disordered configuration to a more compact configuration compared to a Gaussian chain that is defined by the additional links, as demonstrated by coarse-grained simulation. The dynamics of the disordered chain is described by Zimm dynamics with internal friction (ZIF) between neighboring amino acids. Relaxation times are dominated by mode-independent internal friction. Internal friction relaxation times show an Arrhenius-like behavior with an activation energy of 33 kJ/mol. The Zimm dynamics is dominated by internal friction and suggest that the characteristic motions correspond to overdamped elastic modes similar to the motions observed for folded proteins but within a pool of disordered configurations spanning the configurational space. For IDP, internal friction dominates while solvent friction and hydrodynamic interactions are smaller corrections.

Keyword(s): Polymers, Soft Nano Particles and Proteins (1st) ; Biology (2nd)

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Contributing Institute(s):

1. JCNS-FRM-II (JCNS-FRM-II)
2. Heinz Maier-Leibnitz Zentrum (MLZ)
3. Neutronenstreuung (JCNS-1)
4. Streumethoden (JCNS-2)
5. JCNS-4 (JCNS-4)

Research Program(s):

1. 6G4 - Jülich Centre for Neutron Research (JCNS) (FZJ) (POF4-6G4) (POF4-6G4)

Experiment(s):

1. KWS-2: Small angle scattering diffractometer (NL3ao)
2. Facility (machine) DORIS III

Appears in the scientific report 2021

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Database coverage:
; ; Clarivate Analytics Master Journal List ; Current Contents - Physical, Chemical and Earth Sciences ; Ebsco Academic Search ; Essential Science Indicators ; IF < 5 ; JCR ; SCOPUS ; Science Citation Index Expanded ; Web of Science Core Collection

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