engleski

the formation of CaCO3 polymorphs: a comparison of plant and bacterial ureases

Precipitation processes of carbonate particles of different size, shape, and surface properties have been intensively investigated due to their importance in geo- and biosciences, and in numerous industrial applications. This study describes and discusses a conceptually new method for the precipitation of calcium carbonate polymorphs, effectuated through catalytic decomposition of urea by urease enzymes in solutions of calcium salts [1–2]. Specifically the influence of primary structures of plant (Canavalia ensifomis) and bacterial (Bacillus pasteurii) ureases on the nucleation and growth of carbonate precipitates was investigated. Despite the same catalytic function in decomposition of urea, these ureases exert different influence on the crystal phase formation and on development of unusual morphologies of calcium carbonate polymorphs. These differences may be explained by dissimilarity in amino acid sequences of two examined ureases and their different role in nucleation and physico–chemical interactions with the surface of the growing crystals [3–4]. Finally, this study has demonstrated an example how different organisms in nature have ability to produce proteins with the same function, and how with the slight manipulation in their primary structure they take control over the crystal phase formation and growth processes of biogenic calcium carbonate precipitates. [1] I. Sondi, E. Matijević, J. Colloid. Interface Sci. 2001, 238, 208–214. [2] I. Sondi, E. Matijević, Chem. Mater. 2003, 15, 1322–1326. [3] I. Sondi, B. Salopek-Sondi, Langmuir. 2004, 21, 8876–8882. [4] I. Sondi, S. D. Škapin, B. Salopek-Sondi, Cryst. Growth. Des. 2008, 8, 435–441.

carbonate particles; urease; plant; bacteria; biomimetic

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