For Rich Methyl donors methylating mercury?

Discussion in 'Fibromyalgia Main Forum' started by stacy22, Sep 7, 2008.

  1. stacy22

    stacy22 New Member

    Hi Rich,
    I was hoping you could help with something that I have been trying to figure out for awhile now. I found this these formulas below in a biochemistry book: onlinehttp://scholar.google.com/scholar?hl=en&lr=&q=methylation+of+mercury+compounds+by+methylcobalamin+leif+bertilsson and it has

    CH3+ + Hg0 = CH3Hg+ (Methylmercury)
    CH3dot + Hg+ = CH3Hg+ (Methylmercury)
    CH3:- + Hg2+ = CH3Hg+ (Methylmercury)
    CH3:- + RHg+ = CH3HgR (Methylmercury)

    and the part I'm trying to figure out is what other methyl donors methylate mercury? I have learned from research (if I did my research correctly) that CH3 dot (radical) isn't inside our bodies and it is more so in space. Also HG0 is elemental mercury which is common in thermometers, amalgams ect. and can be methylated by CH3+. Therefore I'm only concerned with CH3+ and CH3:- (methylcarbanion) as far as methylating mercury. And since I know methylcobalamin is CH3:- what are the methly donors forumlas for SAMe's and also other methly donors like foods (turmeric ect.)? Also should these other methl donors be a concern as well to methylating mercury?

    Thanks,
    Sally
    [This Message was Edited on 09/07/2008]
  2. Mikie

    Mikie Moderator

  3. richvank

    richvank New Member

    Hi, Sally.

    Elemental mercury that enters the body by inhalation, such as from amalgams, is oxidized to mercuric ion (Hg++) by the enzyme catalase. Hg++ is the only inorganic form of mercury that remains in the body to a considerable extent. As you cited, this form of mercury can be methylated only by CH3-, the carbanion. According to J.M. Wood ("Biological Cycles for Toxic Elements in the Environment," Science, vol. 183, March 15, 1974, pp. 1049-1052), in normal biochemical systems the only possible donor of the carbanion is methylcobalamin or its derivatives. The other two methyl donors in biochemical systems are SAMe and derivatives of 5-methyltetrahydrofolate. Both transfer the methyl group as CH3+ and are thus not able to methylate mercury.

    Rich
    [This Message was Edited on 09/08/2008]
  4. stacy22

    stacy22 New Member

    Hi Rich,
    I wondered if the elemental mercury changed. That clears up a lot for me. Thank you very much!

    Sally
  5. stacy22

    stacy22 New Member

    Hi again,
    So when hydroxycobalamin is consumed does that mean that when it turns into Glutathionylcobabalamin (proving the correct amount of mole to mole ratio with glutahtione was also consumed) and it is methylated in the cytoplasm to methylcobalamin is it safe from methylating mercury?

    Sally

    My research on the Cobalamin Delivery and Metabolism is cited from below:
    Glutathionylcobalamin is a relatively stable form of cobalamin formed inside the cell with high affinity for cobalamin reductases which convert it to cob(II)alamin. Cbl(II)alamin either binds to methionine synthase in the cytoplasm where it is activated by further reduction and methylation to methylcobalamin or it enters the mitochondria where it is reduced to Cbl(I)alamin, the substrate for cob(I)alamin adenosyltransferase (EC 2.5.1.17). This enzyme forms 5’adenosylcobalamin from ATP and cob(I)alamin.

    [This Message was Edited on 09/09/2008]
    [This Message was Edited on 09/09/2008]
  6. richvank

    richvank New Member

    Hi, Sally.

    I don't know if this has been studied and documented, so I can't cite direct evidence. However, it is my understanding that the cobalamin is normally not converted to methylcobalamin until it is bound to methionine synthase. (Though I've heard that this can also take place in the opposite order, if methylcobalamin is supplied supplementally.) It seems reasonable to me that the methylcobalamin would be in smaller quantity and would have less access to mercury in this state, rather than in the freer state it would have if taken directly as supplemental methylcobalamin or injected into the bloodstream as methylcobalamin. This just seems reasonable to me, but I can't cite evidence to support it.

    Rich
  7. stacy22

    stacy22 New Member

    Hi Rich,
    That makes sense. Thanks

    Sally