RE: specific amino acid restriction does the same thing as calorie restriction?

From: Robert J. Bradbury (bradbury@aeiveos.com)
Date: Sun Apr 20 2003 - 13:03:04 MDT

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    On Sun, 20 Apr 2003, Harvey Newstrom wrote:

    > However, after more thought, I am not sure if this helps avoid protein
    > damage or promote protein recycling.

    Excessive amounts of protein synthesis might require more ATP and thus
    more oxidative stress (damaging DNA). So a proper supply of the non-essential
    amino acids might be a good idea.

    Now whether protein recycling requires even more energy (and therefore creates
    more oxidative stress) is an open question. The article that started this
    discussion from LEF suggests that is not the case or the cell somehow
    compensates for it.

    > Protein damage may occur after the protein is built.

    That, I believe is definitely the normal situation. There are several
    modifications after translation that can damage the structure of the
    protein (especially those that are normally long-lived) -- the protein
    glycosylation that Alteon is trying to reverse with ALT-711 is but
    one of several forms of damage.

    In addition I'm reasonably certain that the enzymes that charge the
    transfer RNA (tRNA) with a specific amino acid are quite specific.
    The ribosome also has some error-correction machinery. So the incorporation
    of an improper or deformed amino acid is a relatively low probability situation.
    There also seem to be mechanisms to detect proteins that don't properly
    fold so they get immediately recycled. How this is pulled off I have no
    idea. But I think one can assume a significant part of the problem comes
    from protein "aging". If one can recycle those that are damaged faster --
    then one presumably ends up a protein pool that functions more
    reliably/efficiently.

    Robert



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