Computer-controlled laboratory apparatuses for real-time monitoring and control of the growth of protein crystals are undergoing development. By use of an apparatus of this type, one can monitor and control several parameters that affect the growth of protein crystals; these parameters include temperature, pH, ionic strength, concentration of solute, rate of change of concentration of solute, and possibly others. One can utilize the monitoring capabilities to make decisions on the basis of the measured parameters. One can utilize the control capabilities to effect precise control of growth; one can also start, stop, or reverse growth at will.
In a representative apparatus of this type, precipitating solutions are mixed in a plastic crystallization chamber. The apparatus includes two syringes connected to the crystallization chamber via plastic tubes. By use of a stepping motor that drives a shuttle, the plunger of one syringe is driven in the emptying direction, while the plunger of the other syringe is driven in the filling direction. Probes to monitor electrical conductivity (as an indication of concentration), pH, ionic strength, and temperature are incorporated into the crystallization chamber. Temperature can be controlled by use of a Peltier-effect (thermoelectric) incubator unit. Electronic circuits for controlling the motor, controlling the temperature, and converting the probe outputs into a digital form readable by the associated computer are contained on a printed-circuit board.
An apparatus of this type can be assembled in building-block fashion: Optionally, it can be constructed without the probes and associated circuitry, which can be added later. Another conceptual variation of the basic design would be a multiplexing design in which multiple syringes, multiple motor drives, and/or a manifold and valves would be used to control flows to multiple crystallization chambers so as to test multiple values of molarity and multiple rates of change of molarity of the crystallizing protein.
In accordance with Public Law 96-517, the contractor has elected to retain title to this invention. Inquiries concerning rights for its commercial use should be addressed to
BioSpace International, Inc.
Attn. Leonard Arnowitz, President
4701 Willard Ave., Suite 1236
Chevy Chase, MD 20815
Refer to MFS-31400, volume and number of this NASA Tech Briefs issue, and the page number.