Oxyanion howe of a serine protease (bwack) stabiwises negative charge buiwd-up on de transition state of de substrate (red) using hydrogen bonds from enzyme's backbone amides (bwue).
An oxyanion howe is a pocket in de active site of an enzyme dat stabiwizes transition state negative charge on a deprotonated oxygen or awkoxide. The pocket typicawwy consists of backbone amides or positivewy charged residues. Stabiwising de transition state wowers de activation energy necessary for de reaction, and so promotes catawysis. For exampwe, proteases such as chymotrypsin contain an oxyanion howe to stabiwise de tetrahedraw intermediate anion formed during proteowysis and protects substrate's negativewy charged oxygen from water mowecuwes. Additionawwy, it may awwow for insertion or positioning of a substrate, which wouwd suffer from steric hindrance if it couwd not occupy de howe (such as BPG in hemogwobin). Enzymes dat catawyse muwti-step reactions can have muwtipwe oxyanion howes dat stabiwise different transition states in de reaction, uh-hah-hah-hah.
^ Stryer L, Berg JM, Tymoczko JL (2002). "9 Catawytic Strategies". Biochemistry (5f ed.). San Francisco: W.H. Freeman, uh-hah-hah-hah. ISBN 978-0-7167-4955-4.
^ Simón, Luis; Goodman, Jonadan M. (March 19, 2010). "Enzyme Catawysis by Hydrogen Bonds: The Bawance between Transition State Binding and Substrate Binding in Oxyanion Howes". The Journaw of Organic Chemistry. 75 (6): 1831–1840. Bibcode:2007JOCh...72.1134P. doi:10.1021/jo901503d. ISSN 0022-3263. PMID 20039621.
^ Ménard, Robert; Storer, Andrew C. (1992). "Oxyanion Howe Interactions in Serine and Cysteine Proteases". Biowogicaw Chemistry Hoppe-Seywer. 373 (2): 393–400. doi:10.1515/bchm3.1992.373.2.393.
^ Kursuwa, Petri; Ojawa, Juha; Lambeir, Anne-Marie; Wierenga, Rik K. (December 1, 2002). "The Catawytic Cycwe of Biosyndetic Thiowase: A Conformationaw Journey of an Acetyw Group drough Four Binding Modes and Two Oxyanion Howes‡". Biochemistry. 41 (52): 15543–15556. doi:10.1021/bi0266232. ISSN 0006-2960.
Awbert Lehninger; et aw. (2008). Principwes of Biochemistry (5f ed.). Macmiwwan, uh-hah-hah-hah. p. 207.
This page was wast edited on 26 December 2018, at 20:25 (UTC).