Interferometric Study of Protein Crystal Growth (IPCG) - MGBX

IPCG Test Cell Interferometer Cell Interference Patterns

Objectives

The objectives of this experiment were: (1) to provide a technology demonstration and development effort of an interferometery system to study Protein Crystal Growth (PCG) in microgravity and (2) to study solute concentration gradients surrounding growing proteins crystals to obtain evidence regarding the role of growth unit aggregation in PCG.

Shuttle-Mir Missions
NASA-6

Approach
IPCG experiment was conducted on the NASA-6 science increment. Dissolved lysozyme was used as the test sample for protein crystal growth. IPCG was designed to study the density of the protein solution that surrounds the growing the crystals. Density gradients were measured with a interferometer. The interferometer used diffracted light projected onto the test samples. The image was recorded by a microscope and video camera assembly. The index of refraction varies in the solution, depending on the density; the net result is a visible light-dark pattern that can be recorded. Variations in the solution density reveals changes in the environment surrounding the growing crystal such as changes in pH, precipitant concentrations, and temperature. Different concentrations of lysozyme and precipitating agents were used to obtain a diverse set of data. IPCG images were stored on a 486 laptop computer.

Results
There were 492 images present on the IPCG computer in lieu of the expected 4,140 possible images. Power outages, possible environmental vibrations, and intermittent automatic camera digitization made the results less than desirable.

The IPCG hardware succeeded magnificently, especially with the commercial PC boards and the data acquisition and control system. Several lessons learned and minor redesigns of the fluid and optics systems should be implemented in any follow-on investigations.

Earth Benefits
The interferometer helps scientists to understand the formation of protein crystals. Improved understanding of the types of variables that influence protein crystal growth will facilitate the growth of better quality protein crystals. Consequently, the growth of higher quality protein crystals could led to the production of new and improved pharmaceuticals.

Publications
None available at this time.

Principal Investigators
Alexander McPherson, Ph.D.
University of California at Irvine

Co-Investigators
Stanley Koszelak, Ph.D.
William Witherow
Marc Pusey, Ph.D.

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Page last updated: 07/16/1999

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