Re: [ccp4bb] L-Dopa Stabilization?
Interesting! So chelation alone wouldn't help because the (non GMO) apples have PPO to catalyze the oxidation in the absence of metals. But the ascorbate keeps things reduced, and the acid raises the midpoint potential of phenolics (a proton is given off going from -OH to =O) making them weaker reducing agents and hence more difficult to oxidize. But Jacob Keller's solutions wouldn't have polyphenol oxidase so he is probably right on target going with some reduction and metal chelation; and as someone else suggested, low pH. eab On 07/03/2014 06:14 PM, David Schuller wrote: On 07/03/14 17:05, Edward A. Berry wrote: I see, L-dopa is a phenolic (o-quinolic actually) compound, same as what gets oxidized in sliced apples to turn them brown. At least, that's the way it used to be. http://www.okspecialtyfruits.com/arctic-apples/about-our-nonbrowning-apples "Truly nonbrowning Arctic^® apples are a brilliantly engineered solution to a real-world problem..." -- === All Things Serve the Beam === David J. Schuller modern man in a post-modern world MacCHESS, Cornell University schul...@cornell.edu
Re: [ccp4bb] L-Dopa Stabilization?
On 07/03/14 17:05, Edward A. Berry wrote: I see, L-dopa is a phenolic (o-quinolic actually) compound, same as what gets oxidized in sliced apples to turn them brown. At least, that's the way it used to be. http://www.okspecialtyfruits.com/arctic-apples/about-our-nonbrowning-apples "Truly nonbrowning Arctic^® apples are a brilliantly engineered solution to a real-world problem..." -- === All Things Serve the Beam === David J. Schuller modern man in a post-modern world MacCHESS, Cornell University schul...@cornell.edu
Re: [ccp4bb] L-Dopa Stabilization?
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 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 -- Confidentiality Notice: This message is private and may contain confidential and proprietary information. If you have received this message in error, please notify us and remove it from your system and note that you must not copy, distribute or take any action in reliance on it. Any unauthorized use or disclosure of the contents of this message is not permitted and may be unlawful. -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 ***
Re: [ccp4bb] L-Dopa Stabilization?
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 -- Confidentiality Notice: This message is private and may contain confidential and proprietary information. If you have received this message in error, please notify us and remove it from your system and note that you must not copy, distribute or take any action in reliance on it. Any unauthorized use or disclosure of the contents of this message is not permitted and may be unlawful. -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 ***
Re: [ccp4bb] L-Dopa Stabilization?
No direct experience, but I think that there is some literature supporting increased stability of L-DOPA drug formulations with ascorbate. - John On Thu, Jul 3, 2014 at 1:34 PM, Keller, Jacob wrote: > 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 > ***
Re: [ccp4bb] L-Dopa Stabilization?
levodopa solutions are stable in refrigerator conditions for a day. You make as much you want and prepare fresh everyday. there is no easy ways On Thu, Jul 3, 2014 at 10:34 AM, Keller, Jacob wrote: > 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 > *** > -- P
[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 ***
