Search results
Results From The WOW.Com Content Network
The side-chain theory (German, Seitenkettentheorie) is a theory proposed by Paul Ehrlich (1854–1915) to explain the immune response in living cells.Ehrlich theorized from very early in his career that chemical structure could be used to explain why the immune response occurred in reaction to infection.
In organic chemistry and biochemistry, a side chain is a chemical group that is attached to a core part of the molecule called the "main chain" or backbone. The side chain is a hydrocarbon branching element of a molecule that is attached to a larger hydrocarbon backbone. It is one factor in determining a molecule's properties and reactivity. [2 ...
Then the cell stops producing all other side chains and starts intensive synthesis and secretion of the antigen-binding side chain as a soluble antibody. Though distinct from clonal selection, Ehrlich's idea was a selection theory far more accurate than the instructive theories that dominated immunology in the next decades.
Side-chain, side chain, or sidechain may refer to: Side chain, a chemical group attached to the main chain or backbone of a molecule, such as a protein; Substituent, an atom or group of atoms substituted in place of a hydrogen atom on the parent chain of a hydrocarbon; Side-chaining, an effect in digital audio processing
This led him to propose a new concept called "side-chain theory". (Later in 1900, he revised his concept as "receptor theory".) Based on his new theory, he postulated that in order to kill microbes, "wir müssen chemisch zielen lernen" ("we have to learn how to aim chemically"). [11] His institute was convenient as it was adjacent to a dye factory.
An alpha-helix with hydrogen bonds (yellow dots) The α-helix is the most abundant type of secondary structure in proteins. The α-helix has 3.6 amino acids per turn with an H-bond formed between every fourth residue; the average length is 10 amino acids (3 turns) or 10 Å but varies from 5 to 40 (1.5 to 11 turns).
However, side-chains can have many degrees of freedom in their bond lengths, bond angles, and χ dihedral angles. To simplify this space, protein design methods use rotamer libraries that assume ideal values for bond lengths and bond angles, while restricting χ dihedral angles to a few frequently observed low-energy conformations termed rotamers .
Side-chain types with two heavy atoms (Val, Ile, Thr) have backbone-dependent interactions with both heavy atoms. Val has CG1 at χ 1 and CG2 at χ 1 +120°. Because Val g+ and g- conformations have steric interactions with the backbone near ψ=120° and -60° (the most populated ψ ranges), Val is the only amino acid where the t rotamer (χ 1 ...