Discipline: Chemistry and Chemical Sciences
Subcategory: Chemistry (not Biochemistry)
Audrey Kishishita - California State University, Los Angeles
Co-Author(s): Joshua Lugo, California State University, Los Angeles; Fabio Rojas, California State University, Los Angeles; Jose Castellon, California State University, Los Angeles ; Xin Wen, PhD, California State University, Los Angeles.
Formation of inorganic salts (i.e., scale deposits) is a problem in industrial and domestic setting. To control scale deposits, chemical scale inhibitors are commonly used. Commercial antiscaling agents include polyelectrolytes that dissociate potentially harmful phosphonates, carboxylates, and sulfonates anionic groups. Thus, it is imperative to identify highly efficient polymeric inhibitors to replace phosphonate inhibitors due to their environmental risks. Ice-binding proteins or antifreeze proteins (AFPs) from cold-adapted organisms can bind to specific ice surfaces, thereby inhibiting the nucleation and crystallization of ice. AFPs can also control the crystallization of some non-ice like compounds by interacting with the crystalline surfaces of these compounds. We correlate the charge and molecular properties of the polyelectrolytes with their efficiencies in inhibiting the scale crystal formation. A beetle AFP from Tenebrio molitor (TmAFP) having regular spaced charged residues on its surfaces is prepared and studied here. Calcium carbonate (CaCO3) is a scalent of interest in this study. We investigate the effects of TmAFP and their mutants on the formation of CaCO3. One TmAFP mutant (D4) was modified with aspartate residues interspersed at equidistance apart from each other. The second TmAFP mutant (N5) was modified by removing all negatively charged residues, aspartate and glutamate, and replacing them with asparagine. Results show that the presence of TmAFP inhibits the formation of CaCO3, resulting much fewer CaCO3 crystals. The effect is more pronounced in the mutants. By analyzing the charged residues on the surfaces of TmAFP and calcite surfaces, we propose that TmAFP may affect the formation of calcite via adsorption to the crystalline surfaces of CaCO3. This study provides better understanding for scale control as well as new designs for green antiscalants.ern2018 abstract.docx
Funder Acknowledgement(s): Grant # HRD-1363399, ACS PRF 54214-UR5.
Faculty Advisor: Xin Wen, PhD., firstname.lastname@example.org
Role: Antifreeze protein growth, expression and purification. Calcite precipitation reaction preparation. Precipitation reaction data collection for zeta potential, conductivity, pH, absorbance. Light microscopy preparation and visualization. Scanning Electron Microscopy sample preparation and visualization. Crystal size calculation and sample preparation with SLS. X-Ray Diffraction sample preparation