title: Cooperativity between pepsin and crystallization of calcium carbonate in distilled water.
abstract: Cooperativity between pepsin and crystallization of calcium carbonate in distilled water was studied. The results show that vaterite was formed under the influence of pepsin and the crystalline product was a composite of vaterite and pepsin. The component of this material was similar to that of nacre. At the same time, the crystallization of calcium carbonate had also an important effect on the secondary structure of the pepsin. The secondary structure of the pepsin was characterized through FT-IR technology. The result indicated that the pure pepsin is composed of 24.38% alpha-helices, 29.91% beta-sheets, 39.32% beta-turns and 6.49% random structures and the pepsin in the CaCO(3)-pepsin solution is composed of 2.09% alpha-helices, 93.304% beta-sheets, 4.592% beta-turns and 0.006% random structure. During the crystallization of the calcium carbonate from the pepsin solution, the secondary structure of the pepsin transformed. These results showed that there was cooperativity between the crystallization of vaterite and the pepsin. The cooperative mechanism is discussed.
authors.affiliation: College of Chemistry and Environmental Science, Henan Normal University, Xinxiang 453002, PR China. lingdingdang@yahoo.com
authors.forename: Lin
authors.initials: L
authors.lastname: Yang
authors.forename: Yuming
authors.initials: Y
authors.lastname: Guo
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Ma
authors.forename: Zhiguo
authors.initials: Z
authors.lastname: Hu
authors.forename: Shufa
authors.initials: S
authors.lastname: Zhu
authors.forename: Xiuying
authors.initials: X
authors.lastname: Zhang
authors.forename: Kai
authors.initials: K
authors.lastname: Jiang
mesh_terms: D002113:Calcification, Physiologic; D002119:Calcium Carbonate / Q000737:chemistry* / Q000494:pharmacology; D003460:Crystallization; D010434:Pepsin A / Q000737:chemistry* / Q000494:pharmacology; D017433:Protein Structure, Secondary / Q000187:drug effects; D017550:Spectroscopy, Fourier Transform Infrared; D014867:Water
chemical_list: D014867:Water; D010434:Pepsin A; D002119:Calcium Carbonate