Biomineralization on Outer Core of Coccolithophores: A Computational Modeling Study on Role of 12-Amino Acid Polypeptides on Calcite Surface Growth

Overview & Synopsis

Abstract: Formation of biominerals is a complex process which is mechanized upon the interaction of various mineral surfaces on biological polymers/oligomers. Coccolithophores are a group of single celled algae found in marine environments, which produces complex calcite mineralized structures on their outer-core known as coccoliths. Formation of this exoskeleton by coccolithophores can be directly linked to the genetic information carried in their DNA pattern. Sequencing of amino acids in a protein is a direct result from the DNA base pair sequence that forms RNA via translation and then protein via transcription. This study analyses the interfacial interaction between organic matrix (polypeptide sequence on coccolithophore outer core) and calcite (104) surfaces and surface steps. Negatively charged and neutral 12-amino acid peptides are placed upon [4 8 -1], [0 1 0] and [4 2 -1] surfaces steps of Calcite (104) surfaces, and using Cerius2 software (Accelrys) and Abalone 2.0 software with modified Universal 1.02 force-field, energetics was studied. It is observed that the proximity of an amino acid residue towards the calcite surface and steps depends largely on the nature of the R group. Energetics also revealed that complex 12-residue amino acids facilitate adsorption on calcite steps compared to simple 3-residue proteins, which may induce the growth of calcite biominerals on a particular phase in outer core.