DYNAMICS OF LAYER GROWTH IN PROTEIN CRYSTALLIZATION

Peter G. Vekilov* and J. Iwan D. Alexander†,

* Department of Chemistry and Center for Microgravity and Materials Research, University of Alabama in Huntsville, RI Building D-29, Huntsville, AL 35899, USA

Phone: (256) 890-6892, Fax: (256) 890 6944, e-mail: peter@cmmr.uah.edu

† Department of Mechanical and Aerospace Engineering and National Center for Microgravity Research on Fluids and Combustion, Glennan 416,
Case Western Reserve University, Cleveland, OH 44106-7222, USA

Phone: (216) 368-6045, Fax: (216) 368-6445, e-mail: ida2@po.cwru.edu

Table of Contents

I. Introduction *

II. Step generation and propagation *

A. Step (growth layer) generation *

1. Dislocations, 2D nucleation and crystallites *

2. Localization of 2D nucleation: bulk-transport non-uniformities and defect pinning *

3. Evolution of the dislocation sources of growth layers *

B. Kinetics of step propagation *

1. The kinetic coefficient for incorporation into steps *

2. Inter-step interactions *

III. Defects, strain, and molecular disorder in protein crystals *

IV. Unsteady growth kinetics and step bunching *

A. Phenomenology and dependence on transport parameters *

B. Correlation between unsteady kinetics and crystal imperfections *

C. Macroscopic models of kinetics unsteadiness and feasibility tests *

1. General considerations *

2. Numerical model *

3. Simulation results *

V. Microscopic mechanisms of instability and step bunching *

A. Linear stability predictions *

B. Numerical simulation of suspected incorporation pathway *

C. Stability with respect to small perturbations *

D. Experimental evidence for the role of perturbation type and magnitude *

VI. Control of kinetic unsteadiness *

A. Experiments with flowing solution *

B. Suppression of unsteadiness with faster bulk transport *

VII. Impurities and kinetic unsteadiness *

VIII. Rationale for system-dependent effects of bulk transport changes on crystal perfection *

A. Pure solutions *

B. Impure proteins *

C. What should we do before conducting low-gravity experiments *

IX. Does step bunching contribute to the slow protein crystal growth? *

X. Concluding remarks *

XI. Acknowledgments *

XII. References *