Editing Side chain (section)

==Usage==

===Organic chemistry===
In [[polymer science]], the side chain of an [[oligomer]]ic or [[polymer]]ic offshoot extends from the [[backbone chain]] of a polymer. Side chains have noteworthy influence on a polymer's properties, mainly its [[polymer#Crystallinity|crystallinity]] and [[density]]. An oligomeric branch may be termed a short-chain branch, and a polymeric branch may be termed a long-chain branch. [[Side group]]s are different from side chains; they are neither oligomeric nor polymeric.<ref>{{GoldBookRef|title=branch (side chain, pendant chain)|file=B00720}}</ref>

===Biochemistry===
In [[protein]]s, which are composed of [[amino acid]] residues, the side chains are attached to the [[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 [[ion|charge]] and [[Chemical polarity|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.<ref name="Textbook">{{cite book |last1=Voet |first1=Donald |url=https://archive.org/details/fundamentalsofbi00voet_0 |title=Fundamentals of Biochemistry: Life at the Molecular Level |last2=Voet |first2=Judith |last3=Pratt |first3=Charlotte |date=2013 |publisher=John Wiley & Sons, Inc. |isbn=9781118129180 |edition=Fourth |location=Hoboken, NJ |url-access=registration}}</ref> 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.<ref>{{cite journal |last1=Andrew |first1=C. D. |last2=Penel |first2=S. |last3=Jones |first3=G. R. |last4=Doig |first4=A. J. |date=2001-12-01 |title=Stabilizing nonpolar/polar side-chain interactions in the alpha-helix |journal=Proteins |volume=45 |issue=4 |pages=449–455 |issn=0887-3585 |pmid=11746692 |doi=10.1002/prot.1161 |s2cid=25739520}}</ref> Spatial positions of side-chain atoms can be predicted based on protein backbone geometry using computational tools for side-chain reconstruction.<ref>{{cite journal |last1=Badaczewska-Dawid |first1=Aleksandra E. |last2=Kolinski |first2=Andrzej |last3=Kmiecik |first3=Sebastian |date=2019-12-26 |title=Computational reconstruction of atomistic protein structures from coarse-grained models |journal=Computational and Structural Biotechnology Journal |volume=18 |pages=162–176 |doi=10.1016/j.csbj.2019.12.007 |pmid=31969975 |pmc=6961067 |issn=2001-0370}}</ref>
[[File:AAs table.png|thumb|Table of amino acids]]