From: Karen Kalumuck (karenk@exploratorium.edu)
Date: Thu Feb 24 2000 - 14:49:51 PST
Date: Thu, 24 Feb 2000 14:49:51 -0800 (PST) Message-Id: <v01540b026317f2bc4f13@[192.174.2.182]> From: karenk@exploratorium.edu (Karen Kalumuck) Subject: asparaginase
Hello, Pinholers!
As promised, I researched the basis of "smelly urine" that happens to some
people who consume asparagus. The following is from a set of genetics
laboratory experiments that can be found on the web at:
http://biology.wright.edu/faculty/krane/112/lab/96/exp6.html
Could be a very interesting experiment to conduct in class, and to examine
the population distribution of this trait. Personally, I'm recessive for
the "o" allele (see below). The odor can be found amazingly fast after
eating asparagus; I just had some last night and smelled it within an hour
of eating!
Have fun! ----Karen
Asparaginase: Individuals who are homozygous for the recessive o allele of
this gene are incapable of making an enzyme involved in the catabolism of
the amino acid asparagine. In these individuals a very odoriferous
metabolic intermediate in that pathway builds up and is rapidly excreted in
their urine. Unfortunately, the intermediate is so odoriferous that
individuals with the dominant O allele of the gene need not wonder what
they are missing even though they can completely catabolize asparagine and
do not excrete the intermediate. Prior to your arrival in the laboratory,
the prep-room personnel will have prepared a small serving of asparagus for
you to consume. The amino acid asparagine gets its name from asparagus
which is particularly rich in that component of proteins. By ingesting
asparagus and drinking a small glass of water you will be able to tell by
the end of the laboratory period if you are capable of completely
catabolizing asparagine - if you are not you will have to urinate and your
urine
will be odoriferous. If you have any doubt by the end of the experiment you
can safely count yourself among those that have at least one copy of the
dominant O allele.
Karen E. Kalumuck, Ph.D.
Biologist
Exploratorium Teacher Institute
3601 Lyon St.
San Francisco, CA 94123
415-561-0313
karenk@exploratorium.edu
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