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Studies on tetragonal lysozyme crystal growth rates
1Universities Space Research Association, Huntsville, AL 35806, USA.
Summary
A new apparatus tracks crystal growth, revealing pH impacts on tetragonal lysozyme faces. Lower solubility requires higher supersaturation for equivalent crystal growth rates.
Area of Science:
- Crystallization Science
- Materials Science
- Biophysics
Background:
- Understanding crystal growth mechanisms is crucial for materials science and drug development.
- Tetragonal lysozyme crystallization is a model system for studying protein crystal growth kinetics.
- Previous studies have explored various factors influencing crystal morphology and growth rates.
Purpose of the Study:
- To develop and utilize a computer-controlled apparatus for simultaneous monitoring of multiple crystal face growth rates.
- To investigate the influence of solution pH on the growth kinetics of the (110) and (101) faces of tetragonal lysozyme.
- To analyze the relationship between supersaturation ratio and crystal face growth rates under varying pH conditions.
Main Methods:
- Development of a multi-crystal tracking apparatus capable of monitoring up to 40 crystals simultaneously.
- Measurement of face growth rates of tetragonal lysozyme at pH 4.0, 4.4, 4.8, and 5.2 in a 0.1 M sodium acetate buffer with 5% NaCl at 295 K.
- Analysis of growth rate data using log-log plots of supersaturation ratio versus growth rate and time-lapse video microscopy.
Main Results:
- Non-linear relationships were observed between log(supersaturation ratio) and log(growth rate), with slopes varying from approximately 8 to 2.
- Lower solubility solutions necessitated higher supersaturation ratios for equivalent growth rates.
- Time-lapse imaging revealed a 'notching' phenomenon at crystal corners at low supersaturations, followed by corner filling and macro-step formation on (101) faces.
Conclusions:
- The developed apparatus enables precise measurement of crystal face growth rates.
- Solution pH significantly influences the growth kinetics of tetragonal lysozyme faces, with notable scattering at pH 4.0.
- Observed growth phenomena, including corner notching and subsequent filling, provide insights into crystal growth mechanisms under varying supersaturation and solution conditions.