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:CCP4BB@JISCMAIL.AC.UK] On Behalf Of Keller,
Jacob
Sent: Thursday, July 03, 2014 1:35 PM
To: CCP4BB@JISCMAIL.AC.UK
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: kell...@janelia.hhmi.org
*******************************************
