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Here, we hypothesize a novel oxygen-free organic chemistry for supporting potential exotic biosystems, which is named CHN biochemistry. This oxygen-free CHN biochemistry starts from simple oxygen-free species (including hydrocarbons, hydrogen cyanide, and nitriles) and produces a range of functional macromolecules that may function in similar ways to terran macromolecules, such as sugars (cyanosugars), acids (cyanoacids), amino acids (amino cyanoacids), and nucleobases (cyanonucleobases). These CHN macromolecules could further interact with each other to generate higher \u201ccyanoester\u201d and \u201ccyanoprotein\u201d systems. In addition, theoretical calculations indicate that the energy changes of some reactions are consistent with their counterparts in Earth's biochemistry. The CHN biochemistry-based life would be applicable in habitats with a low bioavailability of oxygen, such as the alkane lakes of Titan and non-aquatic liquids on extrasolar bodies. Key Words: Oxygen-free biochemistry\u2014Titan\u2014Hydrocarbons\u2014Hydrogen cyanide\u2014Nitriles. Astrobiology 17, 1173\u20131181.<\/jats:p>","DOI":"10.1089\/ast.2016.1574","type":"journal-article","created":{"date-parts":[[2017,11,14]],"date-time":"2017-11-14T14:23:29Z","timestamp":1510669409000},"page":"1173-1181","update-policy":"https:\/\/doi.org\/10.1177\/sage-journals-update-policy","source":"Crossref","is-referenced-by-count":16,"title":["Oxygen-Free Biochemistry: The Putative CHN Foundation for Exotic Life in a Hydrocarbon World?"],"prefix":"10.1177","volume":"17","author":[{"given":"Kong-Peng","family":"Lv","sequence":"first","affiliation":[{"name":"University of Hong Kong","place":["Hong Kong"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lucy","family":"Norman","sequence":"additional","affiliation":[{"name":"University of Hong Kong","place":["Hong Kong"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yi-Liang","family":"Li","sequence":"additional","affiliation":[{"name":"University of Hong Kong","place":["Hong Kong"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"179","published-online":{"date-parts":[[2017,11,1]]},"reference":[{"key":"e_1_3_3_2_1","doi-asserted-by":"publisher","DOI":"10.1089\/153110704323175124"},{"key":"e_1_3_3_3_1","doi-asserted-by":"publisher","DOI":"10.1038\/nature02260"},{"key":"e_1_3_3_4_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.cbpa.2004.10.003"},{"key":"e_1_3_3_5_1","doi-asserted-by":"publisher","DOI":"10.1073\/pnas.0308363101"},{"key":"e_1_3_3_6_1","doi-asserted-by":"publisher","DOI":"10.1016\/0303-2647(87)90024-4"},{"key":"e_1_3_3_7_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.icarus.2014.04.042"},{"key":"e_1_3_3_8_1","doi-asserted-by":"publisher","DOI":"10.1029\/2007GL030978"},{"key":"e_1_3_3_9_1","doi-asserted-by":"publisher","DOI":"10.1039\/c004700g"},{"key":"e_1_3_3_10_1","doi-asserted-by":"publisher","DOI":"10.1016\/S0040-4020(01)99315-9"},{"key":"e_1_3_3_11_1","author":"Frisch M.J.E.A.","year":"2009","unstructured":"Frisch M.J.E.A., , Trucks G.W., , Schlegel H.B., , Scuseria G.E., , Robb M.A., , Cheeseman J.R., , and Nakatsuji H. 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