title: Mimicking the biomolecular control of calcium oxalate monohydrate crystal growth: effect of contiguous glutamic acids.
abstract: Scanning confocal interference microscopy (SCIM) and molecular dynamics (MD) simulations were used to investigate the adsorption of the synthetic polypeptide poly(l-glutamic acid) (poly-glu) to calcium oxalate monohydrate (COM) crystals and its effect on COM formation. At low concentrations (1 μg/mL), poly-glu inhibits growth most effectively in ⟨001⟩ directions, indicating strong interactions of the polypeptide with {121} crystal faces. Growth in <010> directions was inhibited only marginally by 1 μg/mL poly-glu, while growth in <100> directions did not appear to be affected. This suggests that, at low concentrations, poly-glu inhibits lattice-ion addition to the faces of COM in the order {121} > {010} ≥ {100}. At high concentrations (6 μg/mL), poly-glu resulted in the formation of dumbbell-shaped crystals featuring concave troughs on the {100} faces. The effects on crystal growth indicate that, at high concentrations, poly-glu interacts with the faces of COM in the order {100} > {121} > {010}. This mirrors MD simulations, which predicted that poly-glu will adsorb to a {100} terrace plane (most calcium-rich) in preference to a {121} (oblique) riser plane but will adsorb to {121} riser plane in preference to an {010} terrace plane (least calcium-rich). The effects of different poly-glu concentration on COM growth (1-6 μg/mL) may be due to variations between the faces in terms of growth mechanism and/or (nano)roughness, which can affect surface energy. In addition, 1 μg/mL might not be adequate to reach the critical concentration for poly-glu to significantly pin step movement on {100} and {010} faces. Understanding the mechanisms involved in these processes is essential for the development of agents to reduce recurrence of kidney stone disease.
authors: School of Dentistry, Western University, London, Ontario, Canada. bgrohe@uwo.ca
authors: Bernd
authors: B
authors: Grohe
authors: Susanna
authors: S
authors: Hug
authors: Aaron
authors: A
authors: Langdon
authors: Jari
authors: J
authors: Jalkanen
authors: Kem A
authors: KA
authors: Rogers
authors: Harvey A
authors: HA
authors: Goldberg
authors: Mikko
authors: M
authors: Karttunen
authors: Graeme K
authors: GK
authors: Hunter
mesh_terms: D000327:Adsorption; D032701:Biomimetics / Q000379:methods*; D002129:Calcium Oxalate / Q000737:chemistry*; D003460:Crystallization; D007700:Kinetics; D018613:Microscopy, Confocal; D008968:Molecular Conformation; D056004:Molecular Dynamics Simulation; D011099:Polyglutamic Acid / Q000737:chemistry*
chemical_list: D011099:Polyglutamic Acid; D002129:Calcium Oxalate