Enzymatic Approach in Calcium Phosphate Biomineralization: A Contribution to Reconcile the Physicochemical with the Physiological View

Abstract

Biomineralization is the process by which organisms produce hard inorganic matter from soft tissues with outstanding control of mineral deposition in time and space. For this purpose, organisms deploy a sophisticated “toolkit” that has resulted in significant evolutionary innovations, for which calcium phosphate (CaP) is the biomineral selected for the skeleton of vertebrates. While CaP mineral formation in aqueous media can be investigated by studying thermodynamics and kinetics of phase transitions in supersaturated solutions, biogenic mineralization requires coping with the inherent complexity of biological systems. This mainly includes compartmentalization and homeostatic processes used by organisms to regulate key physiological factors, including temperature, pH and ion concentration. A detailed analysis of the literature shows the emergence of two main views describing the mechanism of CaP biomineralization. The first one, more dedicated to the study of in vivo systems and supported by researchers in physiology, often involves matrix vesicles (MVs). The second one, more investigated by the physicochemistry community, involves collagen intrafibrillar mineralization particularly through in vitro acellular models. Herein, we show that there is an obvious need in the biological systems to control both where and when the mineral forms through an in-depth survey of the mechanism of CaP mineralization. This necessity could gather both communities of physiologists and physicochemists under a common interest for an enzymatic approach to better describe CaP biomineralization. Both homogeneous and heterogeneous enzymatic catalyses are conceivable for these systems, and a few preliminary promising results on CaP mineralization for both types of enzymatic catalysis are reported in this work. Through them, we aim to describe the relevance of our point of view and the likely findings that could be obtained when adding an enzymatic approach to the already rich and creative research field dealing with CaP mineralization. This complementary approach could lead to a better understanding of the biomineralization mechanism and inspire the biomimetic design of new materials.

Cooperative Calcium Phosphate Deposition on Collagen-Inspired Short Peptide Nanofibers for Application in Bone Tissue Engineering

“…Moreover, with significant disadvantages of limited supplies, discomfort at the harvest site, immunogenicity, and transmission of infectious diseases, there is a growing need for developing synthetic grafts for the treatment of damaged or diseased mineralized tissues. , Because of the hierarchical complexity of these mineralized tissues, fabrication of ideal synthetic grafts that can fulfill the requirement is still a challenge for material scientists. Mimicking the biological process to construct these mineralized structures has gained attention in the recent years. − A close consideration of the structural composition of bone has revealed that a complex combination of calcium phosphate in the form of the mineral hydroxyapatite, as well as collagenous fibrous proteins, makes up bone and teeth. Bone is a unique tissue with extraordinary mechanical and biological properties due to its intricate nanostructure. , It has been realized that the extracellular matrix, particularly connective tissues with their collagen fibers, is crucial for force transmission and maintenance of the bone structure.…”

Hierarchy of Bioapatites

“…Finally, we calculated the energetic effects of the transformations of bioapatites. Summing up, the bioapatites turned out to be surprisingly logical and ordered structures, with all processes leading to the formation of any form of bioapatite in the human organism strictly coupled, perhaps as a result of enzymatic biomineralization [ 74 ].…”

Guidelines derived from biomineralized tissues for design and construction of high-performance biomimetic materials: from weak to strong

“…Some studies highlighted the roles of enzymes in the mineralization process in vivo . 602 Comparison revealed differences in the morphology and size of products obtained in vitro by chemical precipitation and enzymatic reactions. Alkaline phosphatase is crucial in mineralization; it can initiate the mineralization process by generating orthophosphate ions.…”