Chemical Biosensors Based on Proteins Involved in Biomineralization Processes

Abstract

Biomineralization processes are involved in bone and teeth formation, optical/acoustic/magnetic sensors (Mann, 2001), even as in pathological aspects like cardiovascular calcifications, renal or gallbladder stones and others (Narayana & Subramanian, 2010). A remarkable example is the formation of eggshell in avians. The eggshell is the only rigid part of an avian egg, made up of calcium carbonate and some biological macromolecules. The eggshell is a mineral structure with a highly specialized function (Lammie et al., 2005). The question about the role of individual matrix proteins in avian eggshell calcification is an important subject of investigation (Hincke et al., 1999). This is so because the role of individual matrix proteins in avian eggshell calcification is poorly understood, and has never been investigated as calcium or carbonate’s biosensors have. Lakshminarayanan et al., (2005) have done a comparative study of the structure/function relationship of avian eggshell matrix ansocalcin and ovocleidin-17 (OC-17) proteins. These two proteins belong to the C-type lectin family, and share a high degree of similarity, though they interact differently with the growing calcium carbonate crystals, which suggest that their role in eggshell calcification is different as shown by Reyes-Grajeda et al., (2003). Nowadays, an increasing number of studies in C-type lectin-like proteins contained in the avian eggshell matrix have been reported elsewhere (Drickamer, 1999) but they have not been considered as biological sensors for inorganic ions. In this way, Mann & Siedler have determined the amino acid sequence of OC-17, a major protein of the hen s (Gallus gallus) eggshell (Mann & Siedler, 1999); later, struthiocalcin-1 and 2 (SCA-1 and SCA-2) present in ostrich (Struthio camelus) eggshell matrix (Mann & Siedler, 2004), and they have recently, elucidated the amino acid sequence of two proteins of emu (Dromaius novaehollandiae) dromaiocalcin-1 and 2 and two proteins in rhea (Rhea americana) rheacalcin-1 and 2 (Mann & Siedler, 2006). Mann suggested that the structure of the ostrich eggshell was very similar to that of avian eggshells; for example, ansocalcin had the same number of aminoacid