biophysics vs. biochem speculatin'....

u2528082 at ucsvc.ucs.unimelb.edu.au u2528082 at ucsvc.ucs.unimelb.edu.au
Mon Nov 6 20:29:54 EST 1995

In article <Pine.A32.3.91.951103012735.144337B-100000 at red.weeg.uiowa.edu>, "C. Greiner" <cgreiner at blue.weeg.uiowa.edu> writes:
> On Thu, 2 Nov 1995, George Munson wrote:
>> > 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?
>> Hmm.  Okay this is my best guess and I chose "b."  I doubt tactile
>> perception is sensitive enough to distinguish peptide bonds or aa sequence
>> per se.  What you perceive is the much larger scale of the hair which is
>> of course ultimately a result of c, a, and b.  My guess is softness is
>> related to rigidity or the lack thereof.  Rigidity of the overall hair
>> would likely arise from intermolecular disulfide cross linkages which
>> would be tertiary/quartenary in nature.
>> -- 
>> George Munson
>> BMBCB, Northwestern University
>> Evanston, IL   USA   
>> george-munson at nwu.edu
> Although I agree (mostly) with George I wonder if the answer is not "d" 
> with the "softness" relating to the degree of secretion of oils onto the 
> hair rather than the actual molecular structure of the hair itself. Thus 
> the reason high price furs are often from water associated mammals (oil 
> serves as a water barrier) e.g. beaver, mink, fur seal, otter, etc... 

As all Australians know, the softness of wool is directly associated with
fibre diameter. Wool with diameters over 20 microns is considered
 relativelycoarse and is itchy or scratchy on the skin. Diameters in
 the 12-14 micron range is considered superfine and is soft
to the touch eg. cashmere. EM of these fibres show a relatively scaley appearance.
To think that you can determine aa bonding by touch-wow.
                         John Walker

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