MB vs VD summ.
Home Up Exp. Design Microseeding MB vs VD MB vs VD summ. Harvesting Membrane proteins ORF Clusters Large-scale Xn References

 

Screening: studies comparing microbatch with vapor diffusion

The table below summarizes the results of several studies where microbatch was compared to vapor diffusion in screening experiments (i.e. searching for initial crystallization conditions).  All the studies that we know of have been included.

 

 

 

Proteins

Conditions

 MB

VD

Extra hits for MB %

Unique to MB

Unique to VD

1996

Baldock
et al
.

Douglas Ins.

6

48

43

41

5%

17

15

2000

D’Arcy
et al
.

Hoffmann
– La Roche

10

48

104

62

68%

 

 

2001

Noordeen
et al
.

Novartis Pharma

8

48 - 576

145

153

-5%

95

103

 

M. Sugahara

SPring8

6

288

100

84

19%

 

 

 

TOTAL

 

30

 

392

340

15%

 



All of these studies except the first used only a "Modified Microbatch" method.  This refers to microbatch modified by using a 50:50 mixture of silicone oil and paraffin oil to cover the drops ("Al's Oil").  The silicone is slightly permeable to water, and allows slow evaporation.  This gives a scanning effect (similar to vapor diffusion with salt, but not PEG) where gradually increasing concentrations of protein and precipitants are sampled.  This method has been shown to find more hits than using pure paraffin and is now generally used for regular microbatch screening experiments.

More recently, D'Arcy and colleagues (2003) have shown that more hits can be found by using pure silicone oil to cover the drops in place of the silicone / paraffin mixture.  The hits also appear much more rapidly - taking about 9 days instead of up to 70 using the mixture.  The disadvantage of using pure silicone is that crystals do not last for long, so this method is particularly suitable for use with automatic imaging systems.


References:

P.F.M. Baldock, V. Mills, P.D. Shaw Stewart. A comparison of microbatch and vapour diffusion for initial screening of crystallization conditions. Journal of Crystal Growth. 168 (1996), pp 170-174 or: http://www.douglas.co.uk/rep2.htm

A. D’Arcy, G.E. Dale, M. Stihle, B. D’Arcy.  Results reported at the 8th International Conference on the Crystallization of Biological Macromolecules, May 18, 2000 .

N. Noordeen and S. Cowan-Jacob.  Novartis Pharma AG. http://www.hamptonresearch.com/stuff/ppt_files/P6.ppt

Misuaki Sugahara, Riken Harima Institute, SPring8.  Personal communication.

A. D'Arcy, A. Mac Sweeney, M. Stihle, A. Haber.  The advantages of using a modified microbatch method for rapid screening of protein crystallization conditions.  Acta Crystallographica Section D 59 (2003), pp 396-399.

 

                                                 ©2004 Douglas Instruments Ltd