Svedberg

Last updated
A laboratory ultracentrifuge. Beckman-Coulter ultracentrifuge XL-100K -01.jpg
A laboratory ultracentrifuge.

In chemistry, a Svedberg unit or svedberg (symbol S, sometimes Sv [a] ) is a non-SI metric unit for sedimentation coefficients. The Svedberg unit offers a measure of a particle's size indirectly based on its sedimentation rate under acceleration (i.e. how fast a particle of given size and shape settles out of suspension). [1] The svedberg is a measure of time, defined as exactly 10−13 seconds (100  fs).

Contents

For biological macromoleculeslike ribosomes, the sedimentation rate is typically measured as the rate of travel in a centrifuge tube subjected to high g-force. [1]

The svedberg (S) is distinct from the SI unit sievert or the non-SI unit sverdrup, which also use the symbol Sv, and to the SI unit Siemens which uses the symbol S too.

Naming

The unit is named after the Swedish chemist Theodor Svedberg (1884–1971), winner of the 1926 Nobel Prize [2] in chemistry for his work on disperse systems, colloids and his invention of the ultracentrifuge. [3]

Factors

The Svedberg coefficient is a nonlinear function. [1] A particle's mass, density, and shape will determine its S value. The S value depends on the frictional forces retarding its movement, which, in turn, are related to the average cross-sectional area of the particle. [1]

The sedimentation coefficient is the ratio of the speed of a substance in a centrifuge to its acceleration in comparable units. A substance with a sedimentation coefficient of 26S (26×10−13 s) will travel at 26 micrometers per second (26×10−6 m/s) under the influence of an acceleration of a million gravities (107 m/s2). [b] Centrifugal acceleration is given as rω2; where r is the radial distance from the rotation axis and ω is the angular velocity in radians per second.

Bigger particles tend to sediment faster and so have higher Svedberg values.

Svedberg units are not directly additive since they represent a rate of sedimentation, not weight. [1]

Use

In centrifugation of small biochemical species, a convention has developed in which sedimentation coefficients are expressed in the Svedberg units.

See also

Footnotes

  1. ↑ Please note that there is an SI unit with the same Sv abbreviation, the sievert.
  2. ↑ 1 G=9.8 m/s2, i.e. approx 10 m/s2; A million G = 106 x 10 m/s2 = 107 m/s2

Related Research Articles

<span class="mw-page-title-main">Ribosome</span> Synthesizes proteins in cells

Ribosomes are macromolecular machines, found within all cells, that perform biological protein synthesis. Ribosomes link amino acids together in the order specified by the codons of messenger RNA molecules to form polypeptide chains. Ribosomes consist of two major components: the small and large ribosomal subunits. Each subunit consists of one or more ribosomal RNA molecules and many ribosomal proteins. The ribosomes and associated molecules are also known as the translational apparatus.

<span class="mw-page-title-main">Centrifuge</span> Device using centrifugal force to separate fluids

A centrifuge is a device that uses centrifugal force to subject a specimen to a specified constant force - for example, to separate various components of a fluid. This is achieved by spinning the fluid at high speed within a container, thereby separating fluids of different densities or liquids from solids. It works by causing denser substances and particles to move outward in the radial direction. At the same time, objects that are less dense are displaced and moved to the centre. In a laboratory centrifuge that uses sample tubes, the radial acceleration causes denser particles to settle to the bottom of the tube, while low-density substances rise to the top. A centrifuge can be a very effective filter that separates contaminants from the main body of fluid.

<span class="mw-page-title-main">Ultracentrifuge</span> Centrifuge for spinning a rotor at very high speeds

An ultracentrifuge is a centrifuge optimized for spinning a rotor at very high speeds, capable of generating acceleration as high as 1 000 000 g. There are two kinds of ultracentrifuges, the preparative and the analytical ultracentrifuge. Both classes of instruments find important uses in molecular biology, biochemistry, and polymer science.

<span class="mw-page-title-main">Centrifugation</span> Mechanical process

Centrifugation is a mechanical process which involves the use of the centrifugal force to separate particles from a solution according to their size, shape, density, medium viscosity and rotor speed. The denser components of the mixture migrate away from the axis of the centrifuge, while the less dense components of the mixture migrate towards the axis. Chemists and biologists may increase the effective gravitational force of the test tube so that the precipitate (pellet) will travel quickly and fully to the bottom of the tube. The remaining liquid that lies above the precipitate is called a supernatant or supernate.

<span class="mw-page-title-main">Differential centrifugation</span> Method of separating particles in a mixture

In biochemistry and cell biology, differential centrifugation is a common procedure used to separate organelles and other sub-cellular particles based on their sedimentation rate. Although often applied in biological analysis, differential centrifugation is a general technique also suitable for crude purification of non-living suspended particles. In a typical case where differential centrifugation is used to analyze cell-biological phenomena, a tissue sample is first lysed to break the cell membranes and release the organelles and cytosol. The lysate is then subjected to repeated centrifugations, where particles that sediment sufficiently quickly at a given centrifugal force for a given time form a compact "pellet" at the bottom of the centrifugation tube.

<span class="mw-page-title-main">Ribosomal RNA</span> RNA component of the ribosome, essential for protein synthesis in all living organisms

Ribosomal ribonucleic acid (rRNA) is a type of non-coding RNA which is the primary component of ribosomes, essential to all cells. rRNA is a ribozyme which carries out protein synthesis in ribosomes. Ribosomal RNA is transcribed from ribosomal DNA (rDNA) and then bound to ribosomal proteins to form small and large ribosome subunits. rRNA is the physical and mechanical factor of the ribosome that forces transfer RNA (tRNA) and messenger RNA (mRNA) to process and translate the latter into proteins. Ribosomal RNA is the predominant form of RNA found in most cells; it makes up about 80% of cellular RNA despite never being translated into proteins itself. Ribosomes are composed of approximately 60% rRNA and 40% ribosomal proteins, though this ratio differs between prokaryotes and eukaryotes.

<span class="mw-page-title-main">Analytical ultracentrifugation</span>

Analytical ultracentrifugation is an analytical technique which combines an ultracentrifuge with optical monitoring systems.

Bacterial translation is the process by which messenger RNA is translated into proteins in bacteria.

In chemistry, the sedimentation coefficient of a particle characterizes its sedimentation during centrifugation. It is defined as the ratio of a particle's sedimentation velocity to the applied acceleration causing the sedimentation.

<span class="mw-page-title-main">Ribosomal protein</span> Proteins found in ribosomes

A ribosomal protein is any of the proteins that, in conjunction with rRNA, make up the ribosomal subunits involved in the cellular process of translation. E. coli, other bacteria and Archaea have a 30S small subunit and a 50S large subunit, whereas humans and yeasts have a 40S small subunit and a 60S large subunit. Equivalent subunits are frequently numbered differently between bacteria, Archaea, yeasts and humans.

A bacterial initiation factor (IF) is a protein that stabilizes the initiation complex for polypeptide translation.

<span class="mw-page-title-main">5S ribosomal RNA</span> RNA component of the large subunit of the ribosome

The 5S ribosomal RNA is an approximately 120 nucleotide-long ribosomal RNA molecule with a mass of 40 kDa. It is a structural and functional component of the large subunit of the ribosome in all domains of life, with the exception of mitochondrial ribosomes of fungi and animals. The designation 5S refers to the molecule's sedimentation coefficient in an ultracentrifuge, which is measured in Svedberg units (S).

<span class="mw-page-title-main">Prokaryotic large ribosomal subunit</span>

50S is the larger subunit of the 70S ribosome of prokaryotes, i.e. bacteria and archaea. It is the site of inhibition for antibiotics such as macrolides, chloramphenicol, clindamycin, and the pleuromutilins. It includes the 5S ribosomal RNA and 23S ribosomal RNA.

<span class="mw-page-title-main">Prokaryotic small ribosomal subunit</span> Smaller subunit of the 70S ribosome found in prokaryote cells

The prokaryotic small ribosomal subunit, or 30S subunit, is the smaller subunit of the 70S ribosome found in prokaryotes. It is a complex of the 16S ribosomal RNA (rRNA) and 19 proteins. This complex is implicated in the binding of transfer RNA to messenger RNA (mRNA). The small subunit is responsible for the binding and the reading of the mRNA during translation. The small subunit, both the rRNA and its proteins, complexes with the large 50S subunit to form the 70S prokaryotic ribosome in prokaryotic cells. This 70S ribosome is then used to translate mRNA into proteins.

Ribosomal particles are denoted according to their sedimentation coefficients in Svedberg units. The 60S subunit is the large subunit of eukaryotic 80S ribosomes, with the other major component being the eukaryotic small ribosomal subunit (40S). It is structurally and functionally related to the 50S subunit of 70S prokaryotic ribosomes. However, the 60S subunit is much larger than the prokaryotic 50S subunit and contains many additional protein segments, as well as ribosomal RNA expansion segments.

The eukaryotic small ribosomal subunit (40S) is the smaller subunit of the eukaryotic 80S ribosomes, with the other major component being the large ribosomal subunit (60S). The "40S" and "60S" names originate from the convention that ribosomal particles are denoted according to their sedimentation coefficients in Svedberg units. It is structurally and functionally related to the 30S subunit of 70S prokaryotic ribosomes. However, the 40S subunit is much larger than the prokaryotic 30S subunit and contains many additional protein segments, as well as rRNA expansion segments.

<span class="mw-page-title-main">Protein synthesis inhibitor</span> Inhibitors of translation

A protein synthesis inhibitor is a compound that stops or slows the growth or proliferation of cells by disrupting the processes that lead directly to the generation of new proteins.

<span class="mw-page-title-main">Eukaryotic ribosome</span> Large and complex molecular machine

Ribosomes are a large and complex molecular machine that catalyzes the synthesis of proteins, referred to as translation. The ribosome selects aminoacylated transfer RNAs (tRNAs) based on the sequence of a protein-encoding messenger RNA (mRNA) and covalently links the amino acids into a polypeptide chain. Ribosomes from all organisms share a highly conserved catalytic center. However, the ribosomes of eukaryotes are much larger than prokaryotic ribosomes and subject to more complex regulation and biogenesis pathways. Eukaryotic ribosomes are also known as 80S ribosomes, referring to their sedimentation coefficients in Svedberg units, because they sediment faster than the prokaryotic (70S) ribosomes. Eukaryotic ribosomes have two unequal subunits, designated small subunit (40S) and large subunit (60S) according to their sedimentation coefficients. Both subunits contain dozens of ribosomal proteins arranged on a scaffold composed of ribosomal RNA (rRNA). The small subunit monitors the complementarity between tRNA anticodon and mRNA, while the large subunit catalyzes peptide bond formation.

Ribosomopathies are diseases caused by abnormalities in the structure or function of ribosomal component proteins or rRNA genes, or other genes whose products are involved in ribosome biogenesis.

<span class="mw-page-title-main">Polysome profiling</span>

Polysome profiling is a technique in molecular biology that is used to study the association of mRNAs with ribosomes. It is important to note that this technique is different from ribosome profiling. Both techniques have been reviewed and both are used in analysis of the translatome, but the data they generate are at very different levels of specificity. When employed by experts, the technique is remarkably reproducible: the 3 profiles in the first image are from 3 different experiments.

References

  1. 1 2 3 4 5 6 7 Slonczewski, Joan; Foster, John Watkins (2009). Microbiology: An Evolving Science. New York: W.W. Norton. ISBN   9780393978575.
  2. ↑ "The Nobel Prize in Chemistry 1926".
  3. ↑ Koehler, Christopher S. W. (2003). "Developing the Ultracentrifuge" (PDF). Archived from the original (PDF) on 2 October 2023.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.