<Are you saying that the N-terminus of the N-terminal Cysteine residue
has
been modified? If so, would that not result in a blocked N-terminus
which
is not susceptible to Edman degradation?
By the way, we observed the phenomena of a strong "trp" signal on a
different protein with an N-terminal cys after it had been run on a gel
and
blotted without prior alkylating of any sort step.
Kristine Swiderek, Ph.D.>
~~~~~~~~~~~~~~~~~~~~~~~~~~~
Kristine:
Theoretically, each N-terminal Cysteine moiety can react with 3
molecules of alkylating agent, and such modification, (Pam)2-Cys(Pam),
will, of course, make Edman degradation impossible.
Although exhaustive alkylation cannot be excluded completely, I would
expect mono-N-alkylation to be the most probable giving rise to acyclic
imino acid:
H2NC(O)CH2CH2-NH-CH[CH2SCH2CH2C(O)NH2]C(O)-...
with reactivity towards PITC similar to that of proline.
Regards,
Igor Rodionov
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