Hi, I have to prepare L-cysteine solution in HCl and water but don't know the recipe. Can anyone please suggest me the protocol to prepare this solution.
Hi Priyanka Srivastava ,
The main thing you want to keep in mind with cysteine is that it is sensitive to redox potential. If you want it to stay dissolved in its reduced form you will need to prepare it in an anaerobic chamber that has been stripped of oxygen. Similarly, you will need to use ultrafiltered water that has been autoclaved, bubbled with nitrogen or argon to remove oxygen and conditioned in the glovebox for at least 24 hours with the cap loose. From there, you can use conditioned equipment that is devoid of oxygen to prepare your stock to the desired concentration bearing in mind the solubility limit. As an extra precaution, I would recommend filter sterilizing that solution with a syringe filter and 0.2 µm pore size filter.
I know this seems like an intense protocol but you would be surprised at just how sensitive cysteine can be and how often it is not handled properly. The same things I mention above can also be applied to sodium sulphide.
My colleague Ben Stenzler is well-versed in such protocols if you have any other questions and I would point you towards a chapter in my PhD thesis where we exposed obligate anaerobes to differing levels of cysteine for further reference (see Chapter 6):
Thesis Photosynthetic and Fermentative Bacteria Reveal New Pathways...
I hope you found this helpful and please don't hesitate to reach out should you have any other questions,
Daniel
Hi,
please look in
https://www.uspharmacist.com/article/l-cysteine-hydrochloride-50-mgml-injection
Thankyou so much your valuable answer. I am new to this work and your protocol and the thesis chapter have been really helpful for me Daniel Gregoire
Thankyou for your answer. It helped me in many ways. Alaa Kareem Niamah
This product is soluble in 1 M HCl (50 mg/ml), with heat as needed, yielding a clear, colorless solution. The solubility of cystine in water is 0.112 mg/ml at 25 °C; cystine is more soluble in aqueous solutions with pH < 2 or pH > 8.