I have seen ESI-MS spectra during the washout step of Lys-C RP-HPLC maps
which suggested the presence of two high MW species, one around 16 kDa
and the other around 14 kDa. I can't get more specific than that since
the S/N of these spectra was low, I didn't have the full sequence of the
enzyme at the time to confirm my results, and these results were
generated at a former place of employment and are not currently handy.
Nevertheless, if you can find either of these pieces, their size should
make them good high-end calibrants for most Lys-C digests.
Mike Klein
Amgen, Inc.
> ----------
> From: Ulf Hellman[SMTP:ulf.hellman@licr.uu.se]
> Sent: Thursday, February 19, 1998 5:28 AM
> To: Recipients of ABRF List
> Subject: MS - target cleaning etc.
>
> Dear ABRF community,
> Since about 6 weeks we are in the MALDI-TOF business. Great fun and
> impressive sensitivity - a lot of important data has been generated.
> Sofar
> mainly on synthetic and proteolytic peptides, the latter from both
> Coomassie- and silver-stained gels.
> We have a lot of questions; I'll ask the two most urgent ones:
> 1. How to clean the stainless steel targets? Our Bruker Biflex is
> equipped
> with the 26 sample circular holder. We have followed various protocols
> -
> none removes absolutely everything. "Ol' history" is becoming
> annoying!
> 2. I've learnt that internal calibration gives highest accuracy; the
> autodig products of proteolytic enzymes should be ideal. Anyone knows
> if
> the Promega modified trypsin, with its methylated Lys side chains,
> produces
> any useful "calibration standards"? Same for Achromobacter lyticus
> LysC?
> Thanks /Ulf
> ******************************************************
> Ulf Hellman, Ph. D.
> Ludwig Institute for Cancer Research :
> Box 595
> S-751 24 Uppsala
> Sweden
>
> Phone +46 18 160423
> Fax +46 18 160420
> E-mail ulf.hellman@licr.uu.se
> Lab's home page: http://www.licr.uu.se
>