Hi Jim,
We've had trouble getting the theoretical mass of BSA. From a
thermobioanalysis application note, it's 66431 Da. However, if we go
directly from the sequence in Swiss Prot, the mass is 66433 Da for the
reduced form, and 66398 for the form with disulfides (17 of those). I guess
we are dealing w/ the form with disulfides. Yet, if the accuaracy is 0.1%
like Arnie said, it'd be hard to differentiate the two. We also found that
if we used the BSA and RNase A to calibrate the double charge peak of BSA,
it was off from calculated by either of the numbers above, which probably
means the BSA we used has a different mass, as we are pretty confident about
RNase A.
Regards,
Wei
----- Original Message -----
From: "Jim Kerwin" <jlk39@cornell.edu>
To: "Arnie Falck" <falck@pacbell.net>; <wuwei1@msu.edu>
Sent: Wednesday, February 21, 2001 10:19 AM
Subject: Re: Big Proteins on MALDI
>
> Good morning,
>
> Another option: Bovine albumin (66,431) and it's dimer (132,859). If
> you can reliably get ESI spectra from proteins > 50 kDa, please send
> the rest of us details. Regards,
>
> Jim Kerwin
> Mass Spectrometry Facility
> Cornell University
>
>
> >Wei Wu,
> >The best standard at fairly high mass that I am aware of is yeast enolase
> >(Sigma sells it), but it's only about 46k. If you slightly overload the
> >sample, you can see the proton-bound dimer at around 92k, though.
Accuracy
> >somewhat depends on what instrument you are running, and more on how
clean
> >your protein is (narrow peaks=better mass accuracy) but I expect <0.1% on
> >mine for this mass with a good sample. ESI will usually give you better
mass
> >accuracy at this mass, IF you can get the protein to run.
> >Arnie Falick
> >Applied Biosystems
> >FalickAM@appliedbiosystems.com
> >
> >----- Original Message -----
> >From: "Wei Wu" <wuwei1@msu.edu>
> >To: "Recipients of ABRF List" <abrf@aecom.yu.edu>
> >Sent: Monday, February 19, 2001 7:47 PM
> >Subject: Big Proteins on MALDI
> >
> >
> >> Hi Folks,
> >>
> >> I'm trying to do MALDI on a pretty big protein (90k). What are the
mass
> >> standards for that range? Are there any matrixes other than sinapinic
acid
> >> that are worth trying for this big protein? Or there are some special
> >sample
> >> preparation methods? Is it true that I should not expect a good mass
> >accuracy
> >> at this high end?
> >>
> >> Thanks in advacne!
> >>
> >> Wei Wu
> >>
> >> --
> >> 401 BCH
> >> MSU
> >> E. Lansing, MI 48824
> >> 1-517-353-6767
> >>
> >>
>
>
This archive was generated by hypermail 2b29 : Fri Feb 23 2001 - 13:03:34 EST