Department of Chemical & Physical Sciences, University of Toronto at Mississauga, Toronto, Canada.
Department of Physical and Environmental Sciences, University of Toronto Scarborough, Toronto, Canada.
Sci Rep. 2019 Aug 15;9(1):11869. doi: 10.1038/s41598-019-47785-2.
The organic matrix (OM) contained in marine calcifiers has a key role in the regulation of crystal deposition, such as crystalline structure, initiation of mineralization, inhibition, and biological/environmental control. However, the functional properties of the chitin-rich skeletal organic matrix on the biological aspect of crystallization in crustose coralline algae have not yet been investigated. Hence, the characterization of organic matrices in the biomineralization process of this species was studied to understand the functions of these key components for structural formation and mineralization of calcium carbonate crystals. We purified skeletal organic matrix proteins from this species and explored how these components are involved in the mineralization of calcium carbonate crystals and environmental control. Intriguingly, the analytical investigation of the skeletal OM revealed the presence of chitin in the crustose coralline alga Leptophytum foecundum. The sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis of the OM revealed a high molecular mass protein as 300-kDa. Analysis of glycosylation activity exposed two strong glycoproteins as 300-kDa and 240-kDa. Our study of the biominerals of live collected specimens found that in addition to Mg-calcite up to 30% aragonite were present in the skeleton. Our experiment demonstrated that the chitin-rich skeletal OM of coralline algae plays a key role in the biocalcification process by enabling the formation of Mg-calcite. In addition, this OM did not inhibit the formation of aragonite suggesting there is an as yet unidentified process in the living coralline that prevents the formation of aragonite in the living skeletal cell walls.
海生源钙化物质中的有机基质（OM）在晶体沉积的调控中起着关键作用，如晶体结构、矿化启动、抑制和生物/环境控制。然而，富含甲壳质的珊瑚藻骨骼有机基质在生物结晶方面的功能特性尚未得到研究。因此，研究了该物种生物矿化过程中的有机基质特征，以了解这些关键成分在碳酸钙晶体结构形成和矿化中的功能。我们从该物种中纯化了骨骼有机基质蛋白，并探索了这些成分如何参与碳酸钙晶体的矿化和环境控制。有趣的是，骨骼 OM 的分析研究表明，在叶状枝藻 Leptophytum foecundum 中存在甲壳质。OM 的十二烷基硫酸钠-聚丙烯酰胺凝胶电泳（SDS-PAGE）分析显示出一种 300 kDa 的高分子质量蛋白。糖基化活性分析显示出两种强烈的糖蛋白，分子量分别为 300 kDa 和 240 kDa。对活体采集标本生物矿化的研究发现，除了 Mg-方解石外，骨骼中还存在高达 30%的霰石。我们的实验表明，富含甲壳质的珊瑚藻骨骼 OM 通过促进 Mg-方解石的形成，在生物钙化过程中起着关键作用。此外，这种 OM 并没有抑制霰石的形成，这表明在活体珊瑚中存在一个尚未确定的过程，防止了霰石在活体珊瑚骨骼细胞壁中的形成。
