Why only L amino acids?(Why not?)

dallas at mcvax4.d48.lilly.com dallas at mcvax4.d48.lilly.com
Tue Jul 12 12:23:45 EST 1994


I know much of the discussion has been on a serious note, but I tend to like
the "We don't know" theory the best.  Why blow smoke?

One thing I do like is that nature is parsimonious (thrifty for those without
$.25).  At some point (much like when Moses(aka Mel Brooks) came down from the
Mount and dropped one of THE THREE tablets), a choice was made.

(see "History of the World-Part I")

Other explanations:
Life only existed in the Northern hemisphere( what was the structure of
Gondwana Land?). Does life exist in the Southern hemisphere today?  A joke to
my mates in Oz.

We all know the partiality of God to right-handers (if you think of the protein
helix) and that 'left' in Latin is 'sinister'.  God also picked L-amino acids
because he does have a sense of humor and likes to read a good discussion on
the net.

Now serious stuff but questions for thought.

Was the beginning of life proteinaceous or nucleic acid in nature?  I thought
it was AGREED to be proteinaceous.

Should we separate the synthesis of proteins (ribosomal) v. peptides with
D-amino acids (non-ribosomal).  Absolutely!  What does it mean?  I don't know.

Whatever the discussion, systems have to be placed in chronological
(evolutionary) order.  For example, can you have stereochemically favored
enzymatic reactions BEFORE the selection (a presumption) of L-amino acids?

I don't know still seems like the best option.  :-)

Jim Miller
Indianapolis, IN



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