biophysics vs. biochem speculatin'....

Francis Oliver Omana f-omana at ux4.cso.uiuc.edu
Fri Nov 3 03:22:18 EST 1995

mbmorton at ix.netcom.com (michelle morton ) writes:

>Got a question that's been puzzling me.  My cat's fur is so soft that
>petting him is like touching a cashmere or angora sweater.  My question
>is this - is *softness* due to:  

>a) the **physical** arrangement of the peptide bonds - do the bonds and
>the amino acids they're attached to form a smooth, rather than jagged
>or discrete, surface?

>b) the tertiary or quarternary folding of the protein(s) in his fur -
>ie, are the proteins physically arranged in some special way so that
>they are experienced by us as being *soft*?

>c) the sequencing of the amino acids themselves, or

>d) some other phenomenom that I haven't thought of and probably can't
>even imagine right now?

>Obviously, as a student I have wwwaaaaaayyyy too much time on my time
>on my hands :>!!!  This is one of several "philosophy" of chemistry
>questions I have that keep me from ever getting around to figuring out
>how to solve world hunger or bring about total global peace on earth
>and other really important stuff like that!  Soooooooo, if you can help
>me out, I'd really appreciate it.  Thanx in advance for your info.

Cats.   I'm allergic to cats.  But I think they're cute, so I play with
them anyway.  My friends all have short-hair cats, which means their
hairs are kinda fragile and break off.  These fragments are also light
and have a tendency to get caught in my nasal passages and cause a huge
response by my body's immune system.  That is the reason I like long-hair
cats better.  Their hair is much more sturdy and remains in long strands
when they break;  the hair stays on the floor, know what I mean?

Now about cat hair...I haven't read any articles about cat hair, but I do 
know something about human hair..its supercoiled alpha-helical structure, 
for instance.  Human hair breaks and has split ends sometimes too if 
the supercoils start separating.  Hmmm...guess I should start using conditioner
to avoid having  *gasp*  Damaged hair!  "hair, you're damaged goods." I'd say.
Hair conditioner....what a concept.  Back in the old days, did anyone have
shiny, bouncy, silky hair like what you get with a vial of VO5?  Maybe
that's why they wore bonnets and hats in those 19th century photos?
Read the ingredients on a bottle of conditioner.  They're mostly emulsions
of some type or other, and what I think they do (i don't make the product,
i can only hypothesize) is bind to hair and keep the hair strands from
linking to each other.  Penetrating through and coating the hair, the molecules
may provide a more uniform surface than the supercoils alone.  then, as you 
stroke the hair with your fingers, you don't detect roughness on the strands.
Furthermore, these molecules may protect the supercoils from being damaged
physically, chemically or by the sun's radiation.

Water content also plays a role in softness.  Ask someone who uses fabric
softener!  Better yet, which is softer -- a dry towel or a damp one?
have you ever left clothes in a dryer for too long?  Well?  HAVE YOU?

So, to summarize.  your cat's fur is soft probably bacause its hairs are
coated with a natural substance that protects the supercoiled alpha helices
from damage, and/or your cat's hairs retain moisture well.

F.O.  Biophysicist by day, lab vampire at night
f-omana at students.uiuc.edu

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