Something that I was working on, but never really found a good motivating use for:
Use a photoacid (or a "caged proton" the simplest one being a derivatized ortho-nitro benzaldehyde); you can control the pH with something like a UV source like the hand held lamps for looking at TLC plates. LEDs aren't bright enough (I tried). Problems: 1. Aldhyde reactivity 2. Solubility 3. Buffering capacity in the solution and potentially of a solubilizing group on the photoacid. Janko describes a neat little photoacid that you can make pretty easily from vanillin: Biochim Biophys Acta. 1987 Dec 11;905(2):409-16. Proton concentration jumps and generation of transmembrane pH-gradients by photolysis of 4-formyl-6-methoxy-3-nitrophenoxyacetic acid. Janko K, Reichert J. Growing crystals with light controlled pH jumps was a neat idea,it was tough to find a real need for something like it (or even what types of insight it would provide). Not so much help for Andrew, but just a general OT response that I wonder if anyone would have some thoughts on. -----Original Message----- From: [EMAIL PROTECTED] on behalf of Bryan W. Lepore Sent: Mon 12/4/2006 11:41 AM To: Andrew Wong Cc: [email protected] Subject: Re: [ccp4bb]: Decrease pH in xtal drop? *** For details on how to be removed from this list visit the *** *** CCP4 home page http://www.ccp4.ac.uk *** On Mon, 4 Dec 2006, Andrew Wong wrote: > can decrease the pH of the drops on a (somewhat) controlled way, say > over a period of couple of weeks? Thanks could you put a carbon-based stone in the reservoir? so CO2 would slowly leak out? -bryan
