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Biomedical subjects

O G Berg

Publications and source records attributed to O G Berg.

59 records · Page 4Linked to original sources
PubMed1978

Association kinetics with coupled diffusion III. Ionic-strength dependence of the lac repressor-operator association.

The repressor-operator association is treated in a model where the repressor molecule can find its specific binding site, the operator, on a large DNA chain by performing a one-dimensional diffusion along the chain. The ionic-strength dependence is calculated by introducing a screened electrostatic potential around the DNA chain and coupling the free diffusion of the repressor in this potential to the proposed one-dimensional diffusion along the chain. The main influence on the association rate comes from the competitive binding of ions to the unspecific DNA sites. It is also demonstrated that during the time that the repressor is bound in a global sense, the diffusion along the chain will be made up of a strictly one-dimensional motion over fairly short distances, interspersed with many local dissociations during which the repressor in essence is free in solution.

Binding Sites↗
PubMed1977

Association kinetics with coupled diffusion. An extension to coiled-chain macromolecules applied to the lac repressor-operator system.

The association of a molecule onto a specified binding site on a large chain-like macromolecule is described in the "sliding" model, where the molecule is allowed to move along the chain in a one-dimensional diffusion which is coupled to the three-dimensional diffusion in solution. The present work extends a previous one by treating the chains more generally as coiled instead of straight. The model is applied to the lac repressor-operator association. A general expression for the rate of unspecific attachment to a chain-like macromolecule is also derived.

DNA, Bacterial↗
PubMed1976

Association kinetics with coupled diffusional flows. Special application to the lac repressor--operator system.

The time development of the association of the lac repressor to the operator is considered in a model where the repressor is allowed to bind unspecifically to DNA and move along the DNA chain in a one-dimensional diffusion. The coupling to the three-dimensional diffusion outside the chain is introduced by letting the repressor associate and dissociate from the chain until it is finally bound to the operator. All distance correlations along the chain are included. The mean time of association is calculated and through a comparison with experimental data the molecular parameters are determined. The one-dimensional diffusion constant is found to be of the order of 10(-9) cm(2)s(-1). The model is sufficiently general to be applicable to other similar systems.

Diffusion↗