Controlled by Biomolecule Properties

Photo: The skeleton of a seahorse

One ongoing question is how organisms form these mineralized structures, or biominerals, at a controlled rate, sometimes very rapidly until attaining the prescribed size. For reasons not well understood, this process can also go astray, leading to underdevelopment or unwanted growth such as kidney stones. The speed of mineral formation in both normal and pathological development can sometimes be surprisingly fast. For example, phytoplankton, whose occurrence is so extensive that they are believed to have important controls on earth climate, form fully developed and exquisitely shaped skeletons within a few hours.

Virginia Tech Postdoctoral Scientist Selim Elhadj and Professor Patricia Dove reported that the chemistry of organic molecules control the rate of crystal growth. In collaboration with James De Yoreo at Lawrence Livermore National Laboratory and John Hoyer of the Children’s Hospital of Philadelphia, they learned that nano-quantities of biomolecules frequently found in the tissues of organisms where biominerals develop can cause calcite crystals to grow faster.

More importantly, they determined that the speed of growth can be tuned by varying the charge and water-structuring ability of the biomolecules. By finding a relationship between the control of electrical charge and hydrophilicity, respectively, the findings result in a speedometer that predicts the type of molecules that will speed up (or not) crystal growth.

The new insights predict the growth enhancing abilities of amino acids, peptide chains and also explain recent reports of very large growth enhancing effects by natural proteins extracted from the shells of abalone.

Their findings add to intrigue of how proteins and other biomolecules rearrange local water to affect many different aspects of biological systems. To now show that this restructuring also influences the growth of crystals adds new momentum to this research area.; Source: Virginia Tech