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凝乳酶
	牛凝乳酶与抑制剂CP-113972复合物的晶体结构。
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EC編號	3.4.23.4
CAS号	9001-98-3
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凝乳酶（英语：Chymosin或Rennin）是一种在皱胃酶中发现的蛋白酶。它是属于MEROPS A1家族的天冬氨酸蛋白酶。它是由新生反刍动物在皱胃内壁产生的，用于凝结它们摄入的乳汁，从而在肠道中停留更长时间并更好地吸收。它广泛用于奶酪的生产。如今，牛凝乳酶在大肠杆菌、黑曲霉和Kluyveromyces lactis中重组生产，作为替代来源。

发生

虽然凝乳酶著名于由反刍动物在皱胃内壁产生，但它其实广泛存在于所有四足类动物中。^[2]凝乳酶由新生哺乳动物的胃主细胞产生，^[3]用于凝固它们摄入的乳汁，从而在肠道中停留更长时间并更好地吸收。产生凝乳酶的非反刍动物包括猪、猫、海豹^[4]和鸡。^[2]

一项研究报告称在一些人类婴儿身上发现了一种类似凝乳酶的酶，^[5]但其他研究未能复制这一发现。^[6]人类在1号染色体上有一个不产生蛋白质的凝乳酶假基因。^[4]^[7]人类还有其他蛋白质可以消化牛奶，例如胃蛋白酶和脂肪酶。^[8]^:262

除了人类等灵长类动物外，其他一些哺乳动物也失去了凝乳酶基因。^[2]

参考文献

^ PDB 1CZI; Groves MR, Dhanaraj V, Badasso M, Nugent P, Pitts JE, Hoover DJ, Blundell TL. A 2.3 A resolution structure of chymosin complexed with a reduced bond inhibitor shows that the active site beta-hairpin flap is rearranged when compared with the native crystal structure (PDF). Protein Engineering. October 1998, 11 (10): 833–40. PMID 9862200. doi:10.1093/protein/11.10.833 .
^ ^2.0 ^2.1 ^2.2 Lopes-Marques M, Ruivo R, Fonseca E, Teixeira A, Castro LF. Unusual loss of chymosin in mammalian lineages parallels neo-natal immune transfer strategies. Molecular Phylogenetics and Evolution. November 2017, 116: 78–86. PMID 28851538. doi:10.1016/j.ympev.2017.08.014.
^ Kitamura N, Tanimoto A, Hondo E, Andrén A, Cottrell DF, Sasaki M, Yamada J. Immunohistochemical study of the ontogeny of prochymosin--and pepsinogen-producing cells in the abomasum of sheep. Anatomia, Histologia, Embryologia. August 2001, 30 (4): 231–5. PMID 11534329. S2CID 7552821. doi:10.1046/j.1439-0264.2001.00326.x.
^ ^4.0 ^4.1 Staff, Online Mendelian Inheritance in Man (OMIM) Database. Last updated February 21, 1997 Chymosin pseudogene; CYMP prochymosin, included, in the OMIM （页面存档备份，存于互联网档案馆）
^ Henschel MJ, Newport MJ, Parmar V. Gastric proteases in the human infant. Biology of the Neonate. 1987, 52 (5): 268–72. PMID 3118972. doi:10.1159/000242719.
^ Szecsi PB, Harboe M. Chapter 5: Chymosin. Rawlings ND, Salvesen G (编). Handbook of Proteolytic Enzymes 1. 2013: 37–42. doi:10.1016/B978-0-12-382219-2.00005-3 （英语）.
^ Fox PF. Cheese: Chemistry, Physics and Microbiology. 28 February 1999. ISBN 9780834213388.
^ Sanderson IR, Walker WA. Development of the gastrointestinal tract. Hamilton, Ontario: B.C. Decker. 1999. ISBN 978-1-55009-081-9.

延申阅读

Foltmann B. A review on prorennin and rennin. Comptes-Rendus des Travaux du Laboratoire Carlsberg. 1966, 35 (8): 143–231. PMID 5330666.
Visser S, Slangen CJ, van Rooijen PJ. Peptide substrates for chymosin (rennin). Interaction sites in kappa-casein-related sequences located outside the (103-108)-hexapeptide region that fits into the enzyme's active-site cleft. The Biochemical Journal. June 1987, 244 (3): 553–8. PMC 1148031 . PMID 3128264. doi:10.1042/bj2440553.

外部链接

The MEROPS online database for peptidases and their inhibitors: A01.006 （页面存档备份，存于互联网档案馆）

[pmid9862200-1] PDB 1CZI; Groves MR, Dhanaraj V, Badasso M, Nugent P, Pitts JE, Hoover DJ, Blundell TL. A 2.3 A resolution structure of chymosin complexed with a reduced bond inhibitor shows that the active site beta-hairpin flap is rearranged when compared with the native crystal structure (PDF). Protein Engineering. October 1998, 11 (10): 833–40. PMID 9862200. doi:10.1093/protein/11.10.833 .

[lineage-2] 2.0 ^2.1 ^2.2 Lopes-Marques M, Ruivo R, Fonseca E, Teixeira A, Castro LF. Unusual loss of chymosin in mammalian lineages parallels neo-natal immune transfer strategies. Molecular Phylogenetics and Evolution. November 2017, 116: 78–86. PMID 28851538. doi:10.1016/j.ympev.2017.08.014.

[pmid11534329-3] Kitamura N, Tanimoto A, Hondo E, Andrén A, Cottrell DF, Sasaki M, Yamada J. Immunohistochemical study of the ontogeny of prochymosin--and pepsinogen-producing cells in the abomasum of sheep. Anatomia, Histologia, Embryologia. August 2001, 30 (4): 231–5. PMID 11534329. S2CID 7552821. doi:10.1046/j.1439-0264.2001.00326.x.

[OMIM-4] 4.0 ^4.1 Staff, Online Mendelian Inheritance in Man (OMIM) Database. Last updated February 21, 1997 Chymosin pseudogene; CYMP prochymosin, included, in the OMIM （页面存档备份，存于互联网档案馆）

[5] Henschel MJ, Newport MJ, Parmar V. Gastric proteases in the human infant. Biology of the Neonate. 1987, 52 (5): 268–72. PMID 3118972. doi:10.1159/000242719.

[6] Szecsi PB, Harboe M. Chapter 5: Chymosin. Rawlings ND, Salvesen G (编). Handbook of Proteolytic Enzymes 1. 2013: 37–42. doi:10.1016/B978-0-12-382219-2.00005-3 （英语）.

[7] Fox PF. Cheese: Chemistry, Physics and Microbiology. 28 February 1999. ISBN 9780834213388.

[8] Sanderson IR, Walker WA. Development of the gastrointestinal tract. Hamilton, Ontario: B.C. Decker. 1999. ISBN 978-1-55009-081-9.

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