Re: Feathers

[augwhite@neosoft.com (Toby White)]

>Sulfate(sulfur)  excretion has been proposed as a mechanism that led to the
>development of feathers.  What is the basis for the sulfur model?  In hair,
>there are disulfide bonds (as evidenced by the odor that results when one
>has a "perm"), but do feathers have them and to the same degree?

>On the basis of chemical analysis of feathers, what elements are in
>abundance, and what compounds do they tend to be represented in?

Hair and feathers are both made of keratin.  There isn't a lot of chemical
difference between them.  Keratin is a protein, but this doesn't mean it
can't have addends of various kinds (most commonly sugars and fats, but
others are possible).  Most proteins include some cysteine, a
sulfur-containing amino acid, and cysteine-cyseine disulphide bridges are a
common mechanism for cross-linking proteins, including keratin.  However, in
order to use feathers as an excretory system for sulfur, something more
would be required, similarly for nitrogen.  As for sulfur, I have no
comment.  A dump for nitrogen waste products is possible, although I can't
think off-hand of any similar biochemistry elsewhere or any other organism
that surrounds itself with nitrogen waste products.  Various kids of
resonant nitrogen compounds make pretty and interesting colors easily,
although I dunno if this kind of chemistry occurs in vivo.  Might lend
itself to a display function.

  --Toby White