Open AccessEvidence for rotational contribution to protein-facilitated proton transport.
Author(s) -
Gerolf Gros,
Daniel Lavalette,
W. Moll,
H Gros,
B. Amand,
Patrice François
Publication year - 1984
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.81.6.1710
Subject(s) - rotational diffusion , diffusion , earthworm , chemistry , facilitated diffusion , chemical physics , hemoglobin , rotation (mathematics) , rotation around a fixed axis , diffusion process , flux (metallurgy) , biophysics , molecule , physics , thermodynamics , biochemistry , classical mechanics , membrane , biology , organic chemistry , paleontology , geometry , mathematics , innovation diffusion , knowledge management , computer science
Two modes of molecular motion of carrier molecules can, in principle, lead to a facilitated transport of a substrate: translational and rotational diffusion. In the present study, which deals with the mechanism of the facilitated diffusion of H+ and O2 in solutions of earthworm hemoglobin, examples for both types of facilitation are presented. Only translational, not rotational, diffusion of earthworm hemoglobin appears to lead to a facilitated O2 flux. In contrast, substantial facilitated H+ fluxes of comparable size arise from rotational diffusion as well as from translational diffusion of this large protein. This is derived from measurements of facilitated H+ and O2 fluxes in earthworm hemoglobin solutions and determinations of the rotational and translational diffusion coefficients of earthworm hemoglobin with the help of a theoretical treatment of facilitated diffusion by rotational carrier diffusion. H+ transport by rotational protein diffusion appears to be a case where the often-postulated mechanism of facilitated transport by rotation of a carrier lends itself to experimental verification.