Side chain

Source: Wikipedia, the free encyclopedia.
This article is about the chemistry term. For other uses, see Side-chain (disambiguation).
This article is about the side chain of any type of long molecule. For replacement of a hydrogen atom on a hydrocarbon chain, see Substituent.
IUPAC definition

Branch
Side-chain
Pendant chain
An

macromolecular
chain.

Notes

  1. An oligomeric branch may be termed a short-chain branch.
  2. A polymeric branch may be termed a long-chain branch.[1]

In

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] A side chain is also known as a pendant chain, but a pendant group
(side group) has a different definition.

Conventions

The placeholder R is often used as a generic placeholder for

chemical structure diagrams
. To indicate other non-carbon groups in structure diagrams, X, Y, or Z are often used.

History

The R symbol was introduced by 19th-century French chemist

European languages to the initial letter of "root" or "residue": French racine ("root") and résidu ("residue"), these terms' respective English translations along with radical (itself derived from Latin radix below), Latin radix ("root") and residuum ("residue"), and German Rest ("remnant" and, in the context of chemistry, both "residue" and "radical").[3]

Usage

Organic chemistry

In

Side groups are different from side chains; they are neither oligomeric nor polymeric.[4]

Biochemistry

In

alpha-carbon atoms of the amide backbone. The side chain connected to the alpha-carbon is specific for each amino acid and is responsible for determining charge and polarity of the amino acid. The amino acid side chains are also responsible for many of the interactions that lead to proper protein folding and function.[5] Amino acids with similar polarity are usually attracted to each other, while nonpolar and polar side chains usually repel each other. Nonpolar/polar interactions can still play an important part in stabilizing the secondary structure due to the relatively large amount of them occurring throughout the protein.[6] Spatial positions of side-chain atoms can be predicted based on protein backbone geometry using computational tools for side-chain reconstruction.[7]

Table of amino acids

See also

References

  1. S2CID 98774337
    .
  2. ISBN 978-0-321-59231-6
    .
  3. ^ Jensen W.B., Journal of Chemical Education 87, 360 (2010)
  4. doi:10.1351/goldbook.B00720. {{cite book}}: |website= ignored (help
    )
  5. ISBN 9781118129180
    .
  6. S2CID 25739520
    .
  7. PMID 31969975
    .
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