Since no one else seems to have replied, I do know that others have seen
this phenomenon. I remember seeing a poster from a group at Genentech at a
Protein Society meeting that showed covalent modifications by modest
concentrations of PEFABLOC, and to some extent by high concentrations of
PMSF. I believe that was the meeting 3 years ago in Boston, but I
unfortunately can't remember any of the names or even what the protein was.
I don't believe the reactions were at serines, though again my memory may be
wrong about that.
John Philo
Alliance Protein Laboratories
-----Original Message-----
From: Association of Biomolecular Resource Facilities
[mailto:abrf-request@aecom.yu.edu]On Behalf Of Dr K.S. Lilley
Sent: Tuesday, July 28, 1998 6:45 AM
To: Recipients of ABRF List
Subject: Mass spec:PMSF
Dear all,
one of my users has recently supplied me with two proteins for mass
analysis,
one being the wild type and the other a mutant of a 23kDa protein which
binds to
a GTPase causing loss in the latter's activity. In both cases several
species
are present differing by multiples of 155Da from the mass deduced from the
gene
sequence. The user adds relatively high amounts of PMSF to her final
protein
fractions in order to stop proteolysis by a co-purifying protease. We were
therefore wondering whether the discrepancies seen in the mass analysis
were
due to the formation of adducts between PMSF and serine residues within
these
proteins.
Has anyone observed anything like this before?
Kathryn Lilley
Dr. K.S.Lilley
Laboratory Manager
PNACL
University of Leicester
Lancaster Road
Leicester LE1 9HN
tel: 44 116 252 5613
fax: 44 116 252 5616
email: ksl@le.ac.uk