Sedimentation equilibrium
Encyclopedia
Sedimentation equilibrium in a solution or suspension of different particles, such as molecule
s, exists when the rate of transport of each material in any one direction due to sedimentation
equals the rate of transport in the opposite direction due to diffusion
. Sedimentation is due to an external force, such as gravity or centrifugal force
.
It was discovered by Jean Baptiste Perrin
for which he received the Nobel Prize in Physics
in 1926.
. It forms the basis for an analytical ultracentrifugation method for measuring molecular masses, such as those of protein
s, in solution.
Molecule
A molecule is an electrically neutral group of at least two atoms held together by covalent chemical bonds. Molecules are distinguished from ions by their electrical charge...
s, exists when the rate of transport of each material in any one direction due to sedimentation
Sedimentation
Sedimentation is the tendency for particles in suspension to settle out of the fluid in which they are entrained, and come to rest against a barrier. This is due to their motion through the fluid in response to the forces acting on them: these forces can be due to gravity, centrifugal acceleration...
equals the rate of transport in the opposite direction due to diffusion
Diffusion
Molecular diffusion, often called simply diffusion, is the thermal motion of all particles at temperatures above absolute zero. The rate of this movement is a function of temperature, viscosity of the fluid and the size of the particles...
. Sedimentation is due to an external force, such as gravity or centrifugal force
Centrifugal force
Centrifugal force can generally be any force directed outward relative to some origin. More particularly, in classical mechanics, the centrifugal force is an outward force which arises when describing the motion of objects in a rotating reference frame...
.
It was discovered by Jean Baptiste Perrin
Jean Baptiste Perrin
Jean Baptiste Perrin was a French physicist and Nobel laureate.-Early years:Born in Lille, France, Perrin attended the École Normale Supérieure, the elite grande école in Paris. He became an assistant at the school during the period of 1894-97 when he began the study of cathode rays and X-rays...
for which he received the Nobel Prize in Physics
Nobel Prize in Physics
The Nobel Prize in Physics is awarded once a year by the Royal Swedish Academy of Sciences. It is one of the five Nobel Prizes established by the will of Alfred Nobel in 1895 and awarded since 1901; the others are the Nobel Prize in Chemistry, Nobel Prize in Literature, Nobel Peace Prize, and...
in 1926.
Application in determining molecular mass
Sedimentation equilibrium can be used to determine molecular massMolecular mass
The molecular mass of a substance is the mass of one molecule of that substance, in unified atomic mass unit u...
. It forms the basis for an analytical ultracentrifugation method for measuring molecular masses, such as those of protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
s, in solution.