chemoleo - 23-6-2004 at 17:56
I recently found this method on isolating cystine (S-CH2-CH(NH2)-COOH)2, the sulpho-amino acid, from hair:
Admittedly, the ultimate product is cystine, not cysteine. However, a simple reduction yields cysteine (HS-CH2-CH(NH2)-COOH).
Let me elaborate:
The basis of the purification is down to its weak insolubility in weak acids such as acetic acid.
Protocol
1. Weigh out roughly 50 g of well-chopped hair into a beaker, wash free of grease (fats...) with ethanol and dry.
2. Reflux the cleaned hair with 100ml of conc. HCl (presumably 37%), for about 6 hours. This is necessary to split the peptide bonds. The Biuret test
should be negative after. ( Remember, it tests for peptide bonds. Copper sulphate CuSO4 is sufficient to test this).
3. Neutralise the solution to pH 5 by adding a saturated solution of sodium acetate. (I am not sure how this works... but bringing the pH to 5.0 will
be sufficient at this point)
4. Allow the solution to stand overnight, then collect the brown precipitate by filtration.
5. Add 2 gram of active charcoal to the extract, and cautiously bring it to boil. Filter off the charcoal. The filtrate should be colourless.
6. Neutralise the filtrate to pH 5 with a hot saturated solution of Na acetate, then allow the solution to cool, when colourless crystals of cystine
should be deposited.
7. Collect the crystals by the pump (gravity?), wash with a little of cold water and EtOH, and drain well. The yield should be about 3 grams ( I know,
it sucks). Cystine may be purified by recrystallisation from hot water. Don't forget though, there are 20 amino acids, so 3 grams out of 50 is
not bad at all!
What can be done with it??
1) Boil it with 2M NaOH and Pb(Ac)2. Lead sulphide should precipitate.
2) Use a polarimeter to investigate the optical activity of the product. .
3) Use paper chromatography to check for the purity (if interested, ask for details)
To reduce the cystine (which is found in some heatlth products) to cysteine, just use some other strong reductants!
Guess what, I collected about 100 g of hair. My very own, whenever I had the chance.
Admittedly, I dont see why wool (from sheep, etc ) wouldnt work!
[Edited on 26-6-2004 by chemoleo]
Saerynide - 24-6-2004 at 15:23
Some one could try using cat or dog hair, since they shed so much 
Edit: typo
[Edited on 24-6-2004 by Saerynide]
chemoleo - 24-6-2004 at 15:43
How about taking the fur coat from your mom? Probably free of greese, so you won't even waste ethanol
However, I'd like to add - cysteine is an amino acid, one of the twenty encoded ones, of the following structure
HS-CH2-HC(NH2)-COOH
Cystine would be the same as above, but linked via a S-S bond, i.e.
(S-CH2-HC(NH2)-COOH)2
I think cystine is often used as a cold medicine, to decrease mucus formation etc.
In hair and nails, there is between 15-17% cysteine, in long polypeptide chains.
frogfot - 24-6-2004 at 17:13
Finally some real instructions on this extraction. I wanned to do this a long time with my cats hair.. (hihi, I collect em.. 
)
I'm sure the wastewaters can be saved too, to precipitate rest of the aminoacids..
Could H2SO4 be used instead?
chemoleo - 24-6-2004 at 17:30
Probably yes, but you risk sulphonation of other amino acids, i.e. the aromatic ones.
If you dilute it to the conc. of 37%, though, it should be ok I guess.
If you are after other amino acids than cysteine, I would go for HCl though (plus I'd use a different protein source less... milk protein for
instance).
[Edited on 25-6-2004 by chemoleo]
unionised - 25-6-2004 at 14:54
Hair has an higher cystine concentration than most proteins. (the sulphur is part of the reason that burned hair smells so bad). Gelatine is a good
source of proline.
[Edited on 25-6-2004 by unionised]
PHILOU Zrealone - 1-7-2004 at 08:43
White of eggs
and
yellow of eggs (rich at sulfur)
Anyone?
Funny thing is that acid helps polymerisation of the polyamides and make it hard and then redissolve it upon time.
In fact cystin is the disulfide form of cystein.And thus in the formalism of AA it is stil a AA because it has two available CO2H and two available
NH2 hence it forms zwiterions, has a pH isostatic --> out of the 20 usual AA but stil one.
Also to be clear AA are in fact defined restrictively to the natural alfa-AA ; but AAs can be beta, ... omega, unatural. And the too simplistic
definition of AA = NH2-CHR-CO2H with R = H, Alk or Ar is thus too restrictive.
How would you then define:
NH2-CH(CO2H)2 (2 aminomalonic acid)
NH2-CO2H (carbamic acid)
NH2-CH2-CH2-CO2H (3 amino propanoic acid)
NH2-C6H4-CO2H (aminobenzoic acid)
NH2-C(CH3)2-CO2H (geen H in alfa!)
SAY NO TO RACISM AND SEGREGATION AMONGST AA FAMILY!
I HAD A DREAM THAT ONE DAY ALFA AA AND THE OTHER AA WILL WALK TOGETHER IN HARMONY IN A FREE
WORLD!
Those also belongs to the hurge AA family.
To my feeling biuret test will give weird effects of colour even with aminoacids and specially if sulfhydryl group is present. And therefore it should
be tested first for selectivity on cysteine and on cystin vs other AA and vs PA and urea.
[Edited on 1-7-2004 by PHILOU Zrealone]
Blind Angel - 1-7-2004 at 11:24
AA = Amino Acid, a molecule with an Amino part and a Acid part, simple as that.
PHILOU Zrealone - 4-7-2004 at 02:57
GEEN H IN ALFA --> NO H IN ALFA...iw as in stage in holland and so my dutch came out
biochemist - 4-12-2008 at 08:20
What is the point of having large amounts of pure cysteine? Synthesis of a specific reagent from it?
JohnWW - 4-12-2008 at 16:16
It is used as a food supplement for people with a diet deficient in this amino-acid, or in sulfur generally. It can also be synthesized. The synthetic
selenium analog, selenocysteine, is used as a food supplement for selenium deficiency.
[Edited on 6-12-08 by JohnWW]
Sauron - 4-12-2008 at 20:37
Great caution must be exercised in the use of seleno-analog AAs and sodium selenite since the beneficial dosage of Se and the toxic levels are not
very far apart.
Selenomethionine etc are used as animal feed supplements as well.
The seleno-AAs are considered to have much more bioavailable Se than the inorganic Se compounds.
16MillionEyes - 26-2-2009 at 20:03
Funny thing is that I had thought of a similar synthesis (obviously without the more concrete details) for hair and come up with a way to isolate some
AA from it. I'd be curious to know where you got 50g of hair from (*expects to see a bald-spot somewhere*) although technically that isn't that much hair. I was also wondering if you tried to isolate any of the other AAs
left in solution and whether you had any success. I'm wondering how useful it is for other aminoacids, but to be honest, a lot of pure AAs can be
bought OTC from a vitamin store although more costly
kclo4 - 26-2-2009 at 20:19
The various bunch of amino acids might find use in culturing something. They often use various amino acids in different mixtures for that sort of
thing don't they?
panziandi - 27-2-2009 at 13:36
Decarboxylation of some amino acids may yield some usefull and/or interesting amines too. I suppse destructive distillation of cysteine would give the
sulphur analog of aminoethanol ie aminoethanethiol.
chemoleo - 27-2-2009 at 15:09
except I don't think destructive destillation of a cysteine works without oxidising/derivatising it. the SH is too reactive.
You will have more luck with i.e. tryptophan, phenylalanine etc. Then of course there's the idea of diazotisation of the NH2s, there could be a
variety of interesting products made from it...
sparkgap - 27-2-2009 at 19:43
"I'd be curious to know where you got 50g of hair from"
Some barbers do not at all mind (well, except for strange looks. ) giving away
hair clippings.
sparky (~_~)