A high diffusion coefficient for coenzyme Q10 might be related to a folded structure

Area of Science:

• Biochemistry and Biophysics
• Membrane Biophysics
• Lipid Bilayer Dynamics

Background:

• Coenzyme Q (CoQ) is crucial for cellular energy production.
• Understanding CoQ diffusion in lipid membranes is vital for its biological function.
• Previous studies lacked precise measurements of CoQ homologue diffusion in model systems.

Purpose of the Study:

• To experimentally determine the lateral diffusion coefficients of various coenzyme Q homologues and analogues.
• To theoretically model CoQ diffusion using free volume theory.
• To elucidate the relationship between CoQ molecular structure and its membrane mobility.

Main Methods:

• Utilized fluorescence collisional quenching with pyrene derivatives to measure lateral diffusion in model lipid vesicles.
• Employed molecular dynamics computer simulations to determine the geometries and volumes of coenzyme Q molecules.
• Calculated theoretical diffusion coefficients based on free volume theory and simulated molecular dimensions.

Main Results:

• Experimental diffusion coefficients for coenzyme Q homologues were found to be in the range of 10(-6) cm2/s.
• Molecular dynamics simulations revealed surprisingly similar sizes for short and long coenzyme Q homologues.
• The folded structure of the isoprenoid chain in longer coenzyme Q homologues, like coenzyme Q10 (21 Å length), explains their compact size.

Conclusions:

• The lateral diffusion of coenzyme Q homologues in lipid vesicles is consistent across different chain lengths.
• The free volume theory accurately predicts diffusion coefficients when considering the actual molecular dimensions, including folded structures.
• This study provides a comprehensive understanding of coenzyme Q membrane dynamics and its structural determinants.