I see, L-dopa is a phenolic (o-quinolic actually) compound, same as what gets oxidized
in sliced apples to turn them brown. Juice squeezed from half a lemon works great:
citrate to chelate metals which catalyze the oxidation, ascorbate to reduce
everything back to colorless, and the low pH gives the pie a nice tart
taste XXXX no, adjusts the pH to the comfort zone of L-dopa.
On 07/03/2014 04:38 PM, Prince, D Bryan wrote:
> Dear Jacob,
>
> Please check the following references:
>
> http://www.ncbi.nlm.nih.gov/pubmed/8771063
>
> http://www.ncbi.nlm.nih.gov/pubmed/9251095
>
>>From some limited reading of another paper, it seems like the dark solution could be the conversion of L-Dopa into melanin, which is accelerated in alkaline conditions. The authors were extracting L-Dopa from beans and showed that 3>pH<5 was ideal for maximizing solubility of L-Dopa in solution. They suggested citric acid from fruit juice (Lemon, 10mL/L) for extraction/solubilization of L-Dopa. (www.redalyc.org/pdf/939/93911288017.pdf)
>
> Good luck!
>
> Bryan
>
>
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> -----Original Message-----
> From: CCP4 bulletin board [mailto:[log in to unmask]] On Behalf Of Keller, Jacob
> Sent: Thursday, July 03, 2014 1:35 PM
> To: [log in to unmask]
> Subject: [ccp4bb] L-Dopa Stabilization?
>
> Dear Crystallographers,
>
> Does anyone have experience with co-crystallization of a protein with L-Dopa? In my hands, the L-Dopa degrades in water to a dark solution within 10 minutes. I am thinking of trying some reductants and metal chelation, but a verified successful formula would be much appreciated, and preferably it would be without going into a glove box.
>
> Jacob Keller
>
> *******************************************
> Jacob Pearson Keller, PhD
> Looger Lab/HHMI Janelia Farms Research Campus
> 19700 Helix Dr, Ashburn, VA 20147
> email: [log in to unmask]
> *******************************************
>
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