![]() ![]() Previous studies have reported that peptide sequences from insoluble and soluble matrixes share conserved regions or domains however, shell matrix protein sequences are generally dominated by Asp, Glu, Ser, Ala, Gly, Pro and Cys residues, which are often concentrated in short or long repetitive domains. The mechanism of nacre formation has been studied through extraction and functional studies of various shell matrix proteins (SMPs) nevertheless, nacre biomineralization is a very complex process thus, soluble and insoluble proteins in ethylenediaminetetraacetic acid (EDTA) or 10% acetic acid have been studied because of their biochemical and crystallization nacre properties. The organic matrix guarantees mineral and macromolecule interactions as it has a main role in crystal nucleation and growth. The molecules from the matrix are located either in the inorganic phase (within the calcium carbonate crystal) or between crystals forming the organic framework. Shell formation in mollusks is controlled by epithelial cells from the mantle, the organ responsible for secreting the required components for calcium carbonate crystal biomineralization, such as calcium, carbonate ions and organic macromolecules (proteins, β-chitin, glycoproteins, polysaccharides) that form the organic shell matrix. Nacre has outstanding mechanical properties due to the combination of stiffness, strength, and toughness given by its unique microstructure arrangement. In bivalve shell, calcite forms an outer prismatic layer while aragonite forms flat tablets that assemble in a “brick-wall-like” structure or nacre sheet, forming an inner nacreous layer. ![]() Calcium carbonate is a mineral that can be biomineralized into three polymorphs: vaterite, aragonite, and calcite the last two are commonly found in mollusk shell, the second largest group of metazoans. The biological process by which an organism crystalizes minerals is known as biomineralization. The results obtained indicated that Ps19 might play an important role in nacre growth of mollusk shells. Ps19 partial peptide sequence showed similarity with other known shell matrix proteins, but it displayed similarity with proteins from Crassostrea gigas, Mizuhopecten yessoensis, Biomphalaria glabrata, Alpysia californica, Lottia gigantea and Elysia chlorotica. Additionally, it is capable of inducing aragonite plate crystallization in vitro. Ps19 biochemical characterization showed that it is a glycoprotein that exhibits calcium- and chitin-binding capabilities. Thus, the aim of this study was to identify and characterize a novel protein from the acetic acid-insoluble fraction from the shell of Pteria sterna, named in this study as Ps19, to have a better understanding of the biomineralization process. ![]() However, the shell matrix proteins involved in nacre formation are not fully known. Mollusk shell is composed of two CaCO 3 polymorphs (calcite and aragonite) and an organic matrix that consists of acetic acid- or ethylenediaminetetraacetic acid (EDTA)-soluble and insoluble proteins and other biomolecules (polysaccharides, β-chitin). ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |