Editing Enzyme (section)

=== Catalysis ===

{{See also|Enzyme catalysis|Transition state theory}}

Enzymes can accelerate reactions in several ways, all of which lower the [[activation energy]] (ΔG<sup>‡</sup>, [[Gibbs free energy]])<ref name="Fersht_1985">{{cite book | author = Fersht A | title = Enzyme Structure and Mechanism | publisher = W.H. Freeman | location = San Francisco | year = 1985 | pages = 50–2 | isbn = 978-0-7167-1615-0}}</ref>
# By stabilizing the transition state:
#* Creating an environment with a charge distribution complementary to that of the transition state to lower its energy<ref>{{cite journal | vauthors = Warshel A, Sharma PK, Kato M, Xiang Y, Liu H, Olsson MH | title = Electrostatic basis for enzyme catalysis | journal = Chemical Reviews | volume = 106 | issue = 8 | pages = 3210–3235 | date = August 2006 | pmid = 16895325 | doi = 10.1021/cr0503106 }}</ref>
# By providing an alternative reaction pathway:
#* Temporarily reacting with the substrate, forming a covalent intermediate to provide a lower energy transition state<ref>{{cite book | vauthors = Cox MM, Nelson DL | title = Lehninger Principles of Biochemistry | date = 2013 | publisher = W.H. Freeman | location = New York, N.Y. | isbn = 978-1464109621 | edition = 6th | chapter = Chapter 6.2: How enzymes work | page = 195 }}</ref>
# By destabilizing the substrate ground state:
#* Distorting bound substrate(s) into their transition state form to reduce the energy required to reach the transition state<ref name=PMID12947189>{{cite journal | vauthors = Benkovic SJ, Hammes-Schiffer S | title = A perspective on enzyme catalysis | journal = Science | volume = 301 | issue = 5637 | pages = 1196–1202 | date = August 2003 | pmid = 12947189 | doi = 10.1126/science.1085515 | s2cid = 7899320 | bibcode = 2003Sci...301.1196B }}</ref>
#* By orienting the substrates into a productive arrangement to reduce the reaction [[entropy]] change<ref>{{cite book | author = Jencks WP | title = Catalysis in Chemistry and Enzymology | publisher = Dover | location = Mineola, N.Y | year = 1987 | isbn = 978-0-486-65460-7 }}</ref> (the contribution of this mechanism to catalysis is relatively small)<ref>{{cite journal | vauthors = Villa J, Strajbl M, Glennon TM, Sham YY, Chu ZT, Warshel A | title = How important are entropic contributions to enzyme catalysis? | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 97 | issue = 22 | pages = 11899–11904 | date = October 2000 | pmid = 11050223 | pmc = 17266 | doi = 10.1073/pnas.97.22.11899 | doi-access = free | bibcode = 2000PNAS...9711899V }}</ref>
Enzymes may use several of these mechanisms simultaneously. For example, [[protease]]s such as [[trypsin]] perform covalent catalysis using a [[catalytic triad]], stabilize charge build-up on the transition states using an [[oxyanion hole]], complete [[hydrolysis]] using an oriented water substrate.<ref>{{cite journal | vauthors = Polgár L | title = The catalytic triad of serine peptidases | journal = Cellular and Molecular Life Sciences | volume = 62 | issue = 19–20 | pages = 2161–2172 | date = October 2005 | pmid = 16003488 | doi = 10.1007/s00018-005-5160-x | s2cid = 3343824 | pmc = 11139141 }}</ref>