Applicants will be required to submit a proposal in the suggested format, describing the need for micro gravity crystallization of the candidate protein. Applications will be reviewed by an objective committee and judged on the basis of suitability of the proposal for a flight experiment. International involvement is encouraged.
Since 1985 a number of U.S. space shuttle experiments have been conducted involving the study of protein crystal growth processes in a microgravity environment. The primary focus has been to examine the effects of eliminating (1) density-driven convection in the presence of crystal growth and (2) sedimentation of growing crystals.
To date, microgravity protein crystallization experiments have included liquid-liquid diffusion, vapor diffusion, and temperature-induced crystallization techniques. The Vapor Diffusion Apparatus (VDU) was designed for use on U.S. space shuttle missions and is modeled after the hanging drop method used in the laboratory. Temperature control was introduced on STS-26 (September, 1988) and the experimental results from this mission and several of the following missions indicated greater crystal size (as much as twice the volume), more uniform morphologies, and/or higher resolution diffraction data (0.1 to 0.8 A) than the best crystals of these proteins produced on Earth. In addition to the higher resolution of the data there can be a marked increase in the number of observed reflections throughout the resolution range, often as much as 25%. The improvements in diffraction quality are consistent with a more highly ordered crystalline sample.
Newly developed flight hardware, named Protein Crystallization Apparatus for Microgravity (PCAM), will take advantage of vapor diffusion techniques already widely used in crystallization of proteins by closely approximating the geometry of commonly available crystallization plates. Consequently this apparatus will allow the Co-Investigator to screen for crystallization conditions prior to flight using timelier laboratory hardware and methods. Also under development is a crystallization apparatus utilizing the dialysis method for protein crystal growth. It is anticipated that the Dialysis Crystallization Apparatus for Microgravity (DCAM) will be available for flight experiments in the near future.
These flight opportunities are not in lieu of those which may be available through other Flight principal investigators, for example, participation in additional flight opportunities may be available through Dr. Larry DeLucas or Dr. Alex McPherson. The opportunities presented here aim to broaden the user community and to improve the accessibility of the microgravity environment for the growth of protein crystals for scientific purposes.
REFERENCES:
DeLucas, L. J. et al., "Preliminary Investigation of Protein Crystal Growth Using the Space Shuttle, J. Crystal Growth 76: 681 693, 1986.
DeLucas, L. J. et al., "Protein Crystal Growth in Microgravity, Science, 246: 651 654, 1989
DeLucas, L. J. et al., "Micro gravity Protein Crystal Growth Results and Hardware " Eighth American Conference on Crystal Growth, Vail, Colorado, J. Crystal Growth 109: 12. 1991.
McPherson, A. and Day, J., "Macro molecular Crystal Growth Experiments on International Microgravity Laboratory 1, Protein Science 1: 1254 1268, 1992.
Projected Flight # of Sample Deadline for Mission Flight Date Duration Chambers Proposal STS-63 January 1995 14-16 days 378 July 15, 1994 STS-67 February 1995 8-9 days 378 July 15, 1994 USML-2 September 1995 1-6 days 378 Jan.1, 1995
Guest investigators interested in participating in these upcoming flight opportunities must complete and submit the proposal form. The nature of Space Shuttle flight experiments requires planning well in advance of the actual flight date and for this reason, as well as allowing adequate time for ground-based optimization of crystallization conditions, it is requested that proposal deadlines be met. Proposals received after the deadline will be considered on an individual basis. All proposals received will be kept on file for future flight opportunities unless otherwise requested. Guest investigators may submit more than one candidate, however separate proposals should be completed and submitted for each candidate.
Proposals should be submitted on the enclosed forms. Additional sheets may be attached if necessary. All requested information should be as complete as possible.
The Project Description section should include the following:
A. A brief (2 3 sentence) statement describing the protein (or other) and its usefulness to the general public.
B. A complete discussion of the project significance and objectives.
C. Previous history of the project (including any prior micro gravity crystallization experiments, data analysis, crystallization problems, etc.).
D. Justification for micro gravity crystallization.
E. References
F. A statement confirming the availability of adequate Protein for crystallization screens prior to and during flight experiments, as well as a statement of commitment to follow through on data analysis of micro gravity and ground-based crystals.
G. Proposing Guest Investigators should also confirm the availability of research funding to cover costs of the experiment (travel, shipping, etc.). NASA will not be responsible for providing such funds, however very limited travel support may be available on an individual basis.
Please DO NOT send crystallization conditions! All required information for determining chemical or biological toxicity of accepted projects will be requested at a later time and communicated directly to the NASA Safety Office by the Guest Investigator in order to maintain complete confidentiality. Experimental conditions will not be released to any other organizations.
Proposals should be submitted no later than July 15, 1994 for STS-67 and STS-63 or 4 months prior to the scheduled flight date of interest to: