From: Robert J. Bradbury (bradbury@aeiveos.com)
Date: Sun Apr 20 2003 - 13:03:04 MDT
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
This archive was generated by hypermail 2.1.5 : Sun Apr 20 2003 - 13:12:20 MDT