Microlytic SmartScreen, 3×16, 75ul/well

Introduction

The SmartScreen, from Microlytic, applies the concepts of sparse screens to microfluidic devices.  We developed the SmartScreen to release the power of fluid physics designed into our microfluidic Crystal Former chips.

Try our low cost Crystal Former with SmartScreen system in your crystallization efforts and see the value firsthand.

Overview

Sparse screens^1,2,3 have evolved over time from conditions that gave crystals for a specific protein, or class of protein.  This concept has merit, but given the restrictions of the “trial and error” vapor diffusion methodologies, results are often less than stellar.  Regardless, many groups continue to consume numerous plates and liters of screens hoping for a crystallization event.  It strikes us that it is time for a change.

 During these trying economic times, when budgets are tightening, working in a cost effective way and increasing the probability of crystallization makes a lot of sense. 

The Crystal Former with the SmartScreen system is designed precisely for this purpose.

Crystal Former with the SmartScreen System

Few people dispute the physics behind microfluidics.  However, some first generation microfluidic devices fell short of their promises.  Crystals produced by these devices could not easily be harvested and conditions could not routinely be transferred to other methods (vapor diffusion). 

Crystal Former is different.  It…

Reduces overall cost

Minimizes screen volumes

Reduces labor

Provides easy harvesting of crystals

Increases the hit rate of crystallization

The Crystal Former uses a microfluidics approach: protein and precipitant are dispensed into wells at the ends of a closed capillary.  Diffusion occurs as molecules move from regions of higher concentration to lower concentration.  These molecules diffuse at a rate that is proportional to molecular weight/size.  Smaller molecules, ions, move very fast and high molecular weight polymers (i.e., PEGs, etc…) migrate more slowly.  As a result, the protein is exposed to gradients of conditions.  The protein is gently moved through the many regions of saturated to super-saturated nucleation conditions, producing more beam-quality crystals.

SmartScreenSmartScreen is a custom screen consisting of 48 conditions as 3×16 solution sets, which have been selected from many published sparse screens.  Each well contains approximately 75ul of screen arranged in order of productivity (1 is best, 2 second best, etc…).  Only microliter (ul) volumes are required with the Crystal Former.  <!–[endif]–>- The first 16 conditions should give crystals for over 65% of proteins – The next 16 should raise that number to over 85%<!–[endif]–>- The last 16 should produce more than 94% crystal growth. 

These numbers are based on published data from vapor diffusion experiments. ^4,5,6  Higher yields should be expected based on the feedback from customers currently using the Crystal Former (ask about our case studies).

A Case Study:  The Crystal Former SmartScreen System as a Pilot Screening Tool

A researcher at a large pharmaceutical company had been given a novel protein for crystallization.  It had gone through their standard protocols, with several commercial screens, in a vapor phase diffusion mode (sitting drop), but without a successful result.  None of the screens produced crystals.  He consulted the literature, Kimber et al ⁴ ; he chose the top 16 crystallization conditions from a  screen and tested his protein in the Crystal Former.  One channel produced a crystal, almost suitable for beam analysis.  He was then able to transfer the conditions to their legacy vapor diffusion system, made a grid around the condition from the Crystal Former results, varying PEG, salt and pH, and was also able to grow beam-ready crystals.  In this case, the Crystal Former proved to be a quick and easy pilot screening tool. 

This researcher, using the Crystal Former as a pilot screening tool, produced crystals ready for structural analysis by X-ray.  The time savings and minimized material consumption, paired with a positive result that could not be obtained any other way, makes the Crystal Former system a value added tool. 

The SmartScreen is intended to make this practice, of using minimized screens in a microfluidic device, available to all researchers.

Conclusion

SmartScreen, used with the Crystal Former, provides a cost effective means of producing crystals and is changing the paradigm of commonly used protocols.

Fewer plates!

Less imaging!

Lower screen volumes!

Lower purchase cost of screens!

More beam quality crystals!

Lower waste disposal costs

  References 1 <!–[endif]–>Emerald BioSystems.  Wizard screens™, Cryo ™ screens2 <!–[endif]–>Hampton Research. Crystal Screens, PEG/ion, Peg 6000 grid, Ammonium Sulfate grid.3 <!–[endif]–>Jena Bioscience. JBS Classic, JBS Kinase.4 <!–[endif]–>Kimber, M. et al “Data Mining Crystallization Databases: Knowledge-Based Approaches to Optimize Protein Crystal Screens” (2003) Proteins 51:562-5685 <!–[endif]–>Newman, J. et al “Towards Rationalization of crystallization screening for small to medium sized academic labs the PACT/JCSG+ strategy” (2005); Acta Cryst. D 61, 1426-14316 <!–[endif]–>Page, R. et al “Shotgun strategy for structural genomics: an optimized two-tiered crystallization screen against the Thermotoga maritime proteome” (2003); Acta Cryst. D 59, 1028-10377 <!–[endif]–>Kantardjieff, J. et al “Protein isoelectric point as a predictor for increased crystallization screening efficiency” (2004); Bioinformatics 20, 2162-