In my practice, I never worried about the skin. You need extra care while you mount the crystal. In my case I have used the skin to mount my crystals without any problem. In fact it was much helpful. While mounting, you should not take the crystal covered with the skin.

Best

Syed

--------------------------------------------
On Wed, 2/25/15, Gyanendra Kumar <[log in to unmask]> wrote:

 Subject: Re: [ccp4bb] Skin on drops
 To: [log in to unmask]
 Date: Wednesday, February 25, 2015, 10:45 PM
 
 Adding DTT in
 your protein buffer or crystallization solution may also
 help.You could try increasing amounts of DTT/BME/TCEP
 in your crystallization solution and find a balance between
 reduction of skin formation vs getting crystals.
 Adding 2mM DTT in my protein buffer helped me get
 rid of much of the skin on the drop in which the crystals
 were tightly embedded.
 -Gyan
 On Wed, Feb 25, 2015
 at 3:00 AM, Han Remaut <[log in to unmask]>
 wrote:
 Dear
 Ulrike,
 
 
 
 you could try avoid the drop-air interface by overlying
 sitting drops with silicone oil or a 50/50 silicon/paraffin
 oil mixture. Note that this will alter the kinetics with
 which your drops reach equilibrium, and hence may alter your
 ability to get crystals of the protein. Batch
 crystallization under oil is another option of course.
 
 
 
 Adding some alcohols (5-10% EtOH, isopropanol) or detergent
 (0.5 mM LDAO for example) in your crystallization conditions
 may also be something to consider.
 
 
 
 If none of these work, I'd concentrate on harvesting the
 crystals from the skin. I tend to cut these open from the
 side, flip over the skin so that one has better access to
 the crystals that generally are associated with the inner
 face of the skin. You can try peel the crystals off the
 skin, or cut out a piece of skin surrounding a crystal. That
 will not hurt diffraction quality of the crystals.
 
 
 
 Hope that helps.
 
 
 
 Han
 
 
 
 
 
 
 
 On 25 Feb 2015, at 09:34, Ulrike Demmer wrote:
 
 
 
 > Dear crystallographers,
 
 >
 
 > I am trying to crystallize a soluble protein which
 tends to form aggregates. The crystallization condition is
 20% PEG 3350 + 0,2 M Na-Formate. During the crstallization
 process a thick skin is formed on top of the sitting-drops.
 As well the crystals are buried in precipitate. Before I
 start harvesting I try to remove the skin but still it is
 hardly possible to get any crystals out of these drops.
 
 >
 
 > Any suggestions how to avoid the formation of skin on
 crystallization drops ?
 
 >
 
 > Cheers,
 
 >
 
 > Ulrike
 
 
 
 
 
 Han Remaut, PhD
 
 Laboratory of Structural & Molecular Microbiology
 
 VIB / Vrije Universiteit Brussel
 
 Building E4, Pleinlaan 2
 
 1050 Brussel
 
 
 
 [log in to unmask]
 
 tel. +32-2-629 1923 / +32-499 708050
 
 http://www.vib.be/en/research/scientists/Pages/Han-Remaut-Lab.aspx
 
 
 
 -- 
 Gyanendra
 Kumar, PhD
 St. Jude Children's Research
 Hospital,Department of Structural
 Biology,262, Danny Thomas Place,
 MS-311Memphis, TN 38105Phone:
 901-595-3839
 Cell: 631-875-9189
 -------------------------------------------------------