strange c-terminal deletion casue protein run high in SDS-PAGE

Artem Evdokimov AEVDOKIMOZ at cinci.rr.com
Sun Sep 30 20:08:49 EST 2001


Strange results can occasionally happen due to differences in charge (even
though your protein supposedly is enveloped by SDS). Also, you can have
aggregation/misfolding effects which would result in 'structured' protein
going through the SDS-PAGE (even though it should be unfolded !).
You can also have modification effects diue to the differences in C-termini,
proteolysis, etc.

Finally, how sure you are about accuracy of your gel comparison ? Did you
try mixing the truncated protein with the intact and running that mixture -
does it run as one or two bands ?

Good luck.

A.G.E.
"andor" <maildie at yahoo.com> wrote in message
news:ca997abc.0109292043.71774075 at posting.google.com...
> My protein(CMV-Myc Vector) is around 15KD in a standard 15% SDS-PAGE.
> To argue a question with my classmates:
> In a 15% SDS-PAGE,could protein with one amino acid difference be
> detected?
> I deleted some amino acids at C-terminal in my protein on purpose.
>
> When I deleted the last amino acid in C-terminal, the protein "Del-1"
> run different and to our surprise HIGHER than the full-length protein,
> deleted the last 2 and three amino acid get the same band and both run
> HIGHER than the Del-1.
>
> I have read some posts on this newsgroups ,learned that protein may
> sometimes show a un normal result in SD-PAGE, and to my knowledge one
> amino acid difference can not be detected in a 15% SDS-PAGE,however I
> just can not come up with even a reasonable hypothesis for my strange
> result above?
>
> Are there someone meet the same question with me? I need help!





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