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r-Erythropoetin
Name: Scott W.
Status: Educator
Age: 30s
Location: N/A
Country: N/A
Date: September 2002
Question:
I know they use electrophoresis to test for
r-Erythropoetin, but how can they distinguish between what natural and
what's recombinant?
Replies:
Dear Scott:
According to the following interesting article on "Blood Testing for
Professional Cyclists" by Dr. David T. Martin of the Australian Inst. of
Sport, on the Sportscience Peer-Reviewed web site for Sport Research (
http://www.sportsci.org/news/news9703/AISblood.html ), "the
electrophoretic technique is based on the observation that endogenous EPO
generally has a greater negative charge than rhEPO." (
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_u
ids=8587495&dopt=Abstract ). Commercial rhEPO is produced from Chinese
hamster ovary (CHO) cells. EPO is modified by glycosylation within the
cell after the protein itself is synthesized, and CHO cells generate a
slightly different pattern of glycosylation than the endogenous human
form, which probably accounts for the observed charge differential.
Interestingly, the new, longer lasting version of rhEPO, known as Aranesp,
is artificially hyperglycosylated. I have heard that it is more similar
to the native form of EPO, although I think it is still produced in CHO
cells, and that it is more difficult to distinguish from the endogenous
form, probably because the hyperglycosylation increases its negative
surface charge. There is more info. about Aranesp in this PDF slide show
from Dr. Graham Molineaux of Amgen, although I had a lot of trouble with
it freezing my browser ( http://www.aei.org/past_event/molineux.pdf ).
Thanks a lot for the very interesting question,
Jeff Buzby, Ph.D.
Children's Hospital of Orange County
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Update: June 2012
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