Hi Prem, In addition to other remarks made: - You could dissolve one or more crystals in water and have mass spec done to verify that your crystals are a complex. It takes many crystals (20-30) to make sure on an SDS-PAGE. You will probably need to silver stain the gel to enhance the sensitivity. And optimize for visualizing DNA (of course protein and DNA would each be control lanes). - Apart from optimizing your DNA length and overhang as suggested, you could also try to see what a detergent does for you. My experience is that they can dramatically improve the crystal quality for protein-DNA complexes.
But you first need to know if the crystal consists of both protein and DNA. I am optimistic about the probability. Mark (who apparently is also a dinosaur because he practices room temperature crystallography) -----Original Message----- From: Prem kumar <[email protected]> To: CCP4BB <[email protected]> Sent: Fri, Apr 13, 2012 5:10 am Subject: [ccp4bb] Crystal behave funny Hi all, I got some Protein + DNA complex crystals (image attached) recently. They are needle shape some times splitted chromosome type crystals. When we pick long needles they bend so much than normal crystal but they dont break. The small needle dissolve very fast as try to open the drop's film. we try to diffract the long needle crystals and they diffract up to 20 A resolution. Any suggestion how to improve those crystal packing. Thanks in advance! -Prem
