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Re: Dinosaur Protein
----- Original Message -----
Sent: Friday, April 13, 2007 4:40 PM
[...] DNA has to be able to be opened easily (e.g. unwrapped from
histones and the needed portion transcribed), and this "flexibility" in
conformation is synonymous with breaking down easily.
Why? Aren't most proteins at least as flexible? For transcription and
replication it is only necessary to separate the two strands, not to do any
chemical modifications to the strands themselves. Indeed, for some
experiments with DNA chemistry PNA -- the same with a much more stable
protein backbone -- has been invented. It looks like it is just a historical
coincidence that we got stuck with a sugar-phosphate backbone.
Collagen, on the other hand, is the tough, non-elastic protein in
connective tissue, and has been selected to the opposite selective
pressures the previous several billion years.
(Is collagen itself that old? Isn't it limited to metazoans?)