Dear all,
I know this sounds weird (and besides, it's a non CCP4 question), but
does anyone know any reports or has worked with a recombinant protein
that is apparently post translationally modified by E. coli?
We have an enzyme with two populations that have been sequenced at the
N-terminus. Both have the same sequence at that region, but by mass
spec the MW of one population (1) is 200 Da more than expected. The
other population (2) has the "correct" MW. The enzyme (1) has 10%
activity with respect to (2). The C-terminal is far away from the
active site.
Another funny thing is that the ratio of the two populations changes
from batch to batch, and the heterogeneity arises before cleaving the
N-terminal His tag with TEV protease.
Any comments will be greatly acknowledged. Thanks a lot in advance, Alfredo.
Alfredo Torres-Larios, PhD
Assistant Professor
Instituto de Fisiologia Celular, UNAM
Circuito Exterior S/N. Ciudad Universitaria
Mexico, DF, Mexico
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