Cysteine As A Substrate

Discussion in 'Ray Peat Topics' started by himsahimsa, Feb 28, 2014.

  1. himsahimsa

    himsahimsa Member

    Joined:
    Jan 25, 2014
    Messages:
    148
    Cysteine is the limiting substrate for:

    Glutathion Peroxidase
    Superoxide Dysmutase
    Thyroperoxidase

    These are all very important.

    For instance acetaminophen depletes superoxide dysmutase in the liver so rapidly that 8000mg (or less) acetaminophen can kill the liver and thus the owner of that liver. Without Thyroperoxidase sever damage occurs to the thyroid gland as a result of just making its hormones. Glutathion Peroxidase is used directly in the liver and also everywhere as the peroxidation backstop for immune system activity.

    How can restricting cysteine intake not be a problem?
     
  2. Wilfrid

    Wilfrid Member

    Joined:
    Nov 26, 2012
    Messages:
    669
    Good post.

    Cysteine ,like methionine and tyrosine , is one of the most important human's antioxydant amino acid.

    Differential effects of cysteine and methionine residues in the antioxidant activity of human serum albumin.
    Emmanuel Bourdon, Nadine Loreau, Laurent Lagrost, Denis Blache
    Faculté de Médecine, INSERM U498-Biochimie des Lipoprotéines, Université de Bourgogne, 7, blvd Jeanne d'Arc, BP 87900 21079, Dijon, France.
    Free Radical Research (Impact Factor: 3.28). 02/2005; 39(1):15-20. DOI:10.1080/10715760400024935
    Source: PubMed
    ABSTRACT Antioxidant properties of human serum albumin (HSA) may explain part of its beneficial role in various diseases related to free radical attack. In the present study, the antioxidant role of Cys and Met was studied by copper-mediated oxidation of human low density lipoproteins and by free radical-induced blood hemolysis which essentially assessed metal-chelating and free radical scavenging activities, respectively. Mild conditions were set up to specifically modify Cys and Met residues by N-ethylmaleimide (NEM) and chloramine T treatments, respectively. We found that Met and Cys accounted for 40-80% of total antioxidant activity of HSA. Copper binding to HSA was decreased by about 50% with chloramine T treatment of Met whereas no change was observed after NEM treatment of Cys. Although other amino acid residues are likely to be involved in anti-/prooxidant properties of HSA, from our data, we propose that Cys chiefly works as a free radical scavenger whereas Met mainly acts as a metal chelator.

    That is to say I'm ,too, still confused about Ray's take on cysteine....
     
  3. Blossom

    Blossom Moderator

    Joined:
    Nov 23, 2013
    Messages:
    8,386
    Gender:
    Female
    Here is what I know about Ray's stance on cysteine, in large doses along with methionine and tryptophan it inhibits thyroid function. I will find the source asap. I also read about toxins in the manufacturing process of single amino acids being a concern as well as the bodies utilization as compared to whole protein sources. I'm not sure how this applies to substrates.
     
  4. Blossom

    Blossom Moderator

    Joined:
    Nov 23, 2013
    Messages:
    8,386
    Gender:
    Female
    These two articles specifically:
    Tryptophan,serotonin and aging
    Gelatin, stress and longevity
     
  5. OP
    himsahimsa

    himsahimsa Member

    Joined:
    Jan 25, 2014
    Messages:
    148
    All that looks speculative. I read through everything on the RP site and don't see any mechanism discussed. Maybe in the footnotes. I did read all the footnotes but could have missed something. Even if it is somewhat anti-thyroid, being short the glutathion based enzymes has got to be very bad.

    I took about 1.2 grams N-Acetyl cysteine almost every day for years and did not notice any ill effect and was basically in good health.

    (I run low, 97.4F DEG average, but I always have, since I was little. I know because I have tracked it. I'm trying to goose it up a degree or so now, to no avail, and am being OCD scrupulous about the pro and anti thyroid materials. It's off the subject but any advice on that would be a help. I am homeostatic like a rock. Trying to move my BMR off the peg is not happening.)
     
  6. OP
    himsahimsa

    himsahimsa Member

    Joined:
    Jan 25, 2014
    Messages:
    148
    Here is an abstract RP used. The author was able to reverse thyroid inhibition by increasing available iodide. This is in vitro. I don't know how 12 or 18 millimoles of iodide compares to its concentration in a living thyroid in a living neck. I'm sure it's known. Also, penetration of circulating free inhibitory amino acids into a living thyroid and thus their ability to act on the enzymes is not addressed.
    RP also talks about increased longevity associated with the deficiency of these amino acids independently of this anti-thyroid effect. So...
     
  7. OP
    himsahimsa

    himsahimsa Member

    Joined:
    Jan 25, 2014
    Messages:
    148
  8. Blossom

    Blossom Moderator

    Joined:
    Nov 23, 2013
    Messages:
    8,386
    Gender:
    Female
    Quote from Ray Peat March 2005 Context for Asthma
    "The selection of proteins should minimize the amino acids tryptophan(which is the precursor of serotonin) and cysteine( which like tryptophan, suppresses the thyroid function) by including gelatin and fruits."
     
  9. Blossom

    Blossom Moderator

    Joined:
    Nov 23, 2013
    Messages:
    8,386
    Gender:
    Female
    Quote from Ray Peat's January 2001 newsletter on the topic Fibrosis:
    " Too much glutamine acid, aspartic acid and cysteine can be directly cytotoxic, and the metabolites of cysteine include proinflammatory homocysteine, which can disrupt collagen structure."
     
  10. nograde

    nograde Member

    Joined:
    Oct 21, 2013
    Messages:
    133
    I think that's wrong. Homocysteine is either shunted downwards to cysteine (using B6 as cofactor) or recycled back to methionine (using folate, betaine and choline as cofactor). As far as I know there's no pathway going from cysteine back to homocysteine. See here: http://lpi.oregonstate.edu/infocenter/v ... 6diag.html

    There's no doubt that elevated homocysteine is really bad news, even in "conservative" circles it's implicated in many diseases. I think its clear that avoiding homocysteine buildup is an important goal. However how should we achieve that?

    • Restrict methionine (the precursor)
    • Watch out for good B6 status to transform homocysteine down to cysteine (which RP says is bad for thyroid)
    • Watch out for good Folate, betaine, choline status to recycle it back to methionine (which RP says is bad)

    And how does glycine play into all this? Is there any new information on Ray's stance on this topic?
     
  11. nullredvector

    nullredvector Member

    Joined:
    Oct 17, 2013
    Messages:
    195
    Gender:
    Male
    Occupation:
    UPS
    Location:
    USA
    @nograde raises some really good questions
     
  12. dfspcc20

    dfspcc20 Member

    Joined:
    Dec 9, 2015
    Messages:
    486
    Aren't humans also able to biosynthesize cysteine into taurine?
    I've been wondering what determines how well (or poorly) we make that conversion.
     
  13. Peater Piper

    Peater Piper Member

    Joined:
    Mar 18, 2016
    Messages:
    684
    Gender:
    Male
    Indeed, and does consuming (or supplementing) taurine cause the cysteine to take a different path? It's a pretty complicated process.
     
Loading...