Editing Small molecule (section)

{{Short description|Organic molecule weighing under 1000 daltons}}
In [[molecular biology]] and [[pharmacology]], a '''small molecule''' or '''micromolecule''' is a low molecular weight (≤ 1000 [[Atomic mass unit|daltons]]<ref name = "Dougherty_Pucci_2012">{{cite book |veditors=Dougherty TJ, Pucci MJ | title =  Antibiotic Discovery and Development | year = 2012 | isbn = 978-1-4614-1400-1 | author = Macielag MJ | chapter = Chemical properties of antibacterials and their uniqueness | pages = 801–2 | publisher = Springer | quote = The majority of [oral] drugs from the general reference set have molecular weights below 550. In contrast the molecular-weight distribution of oral antibacterial agents is bimodal: 340–450 Da but with another group in the 700–900 molecular weight range. | chapter-url = https://books.google.com/books?id=av5SHPiHVcsC&q=oral%20drug%20molecular%20weight%20distribution%20antibiotics&pg=PA800 }}</ref>) [[organic compound]] that may regulate a biological process, with a size on the order of 1&nbsp;nm{{Citation needed|date=June 2021}}. Many [[pharmaceuticals|drugs]] are small molecules; the terms are equivalent in the literature. [[macromolecule|Larger structures]] such as [[nucleic acid]]s and [[protein]]s, and many [[polysaccharides]] are not small molecules, although their constituent monomers (ribo- or deoxyribonucleotides, [[amino acid]]s, and monosaccharides, respectively) are often considered small molecules. Small molecules may be used as research tools to probe [[function (biology)|biological function]] as well as [[lead compound|leads]] in the development of new [[pharmaceutical drug|therapeutic agents]]. Some can inhibit a specific function of a protein or disrupt [[protein–protein interaction]]s.<ref name="pmid15060526">{{cite journal |vauthors=Arkin MR, Wells JA | title = Small-molecule inhibitors of protein-protein interactions: progressing towards the dream | journal = Nature Reviews Drug Discovery | volume = 3 | issue = 4 | pages = 301–17 |date=April 2004 | pmid = 15060526 | doi = 10.1038/nrd1343 | s2cid = 13879559 }}</ref>

[[Pharmacology]] usually restricts the term "small molecule" to molecules that bind specific biological [[macromolecules]] and act as an [[effector (biology)|effector]], altering the activity or function of the [[biological target|target]]. Small molecules can have a variety of biological functions or applications, serving as [[cell signaling]] molecules, [[drug]]s in [[medicine]], [[pesticide]]s in farming, and in many other roles. These compounds can be natural (such as [[secondary metabolites]]) or artificial (such as [[antiviral drug]]s); they may have a beneficial effect against a disease (such as [[pharmaceuticals|drugs]]) or may be detrimental (such as [[teratogen]]s and [[carcinogen]]s).