I want to thank all those who responded to my recent question concerning
appropriate vendors for mass spec standards. Your comments and experience
are deeply appreciated. Below is a compliation of the replies I received
for anyone interested.
Thanks,
Bill
>Bill-
>The bad news is that Sigma proteins are usually nowhere near as clean as
>they claim. The intermediate news is that, unless you're purifying the
>proteins yourself, no one else makes them any better. The good news is that
>Sigma products are usually affordable. The great news is that you have two
>new mass specs, making the purity insignificant, since you can select
>whatever signals you want to tune on. Be prepared to make a boatload of
>aliquots, then freeze them, and try to limit the number of times you use a
>single aliquot or how long it's kept thawed. This way, you limit the
>degradation and get consistent results for a longer period of time.
>-Mike
>
>Michael L. Klein, Ph.D.
>Research Scientist
>Analytical Research & Development
>Amgen, Inc.
>One Amgen Center Drive
>M/S 25-2-A
>Thousand Oaks, CA 91320
>(805) 447-2773
>FAX (805) 447-8690
>Bill,
>SIGMA, in my experience, has been an OK source for these protein standards
>(unlike enzymes). Buy the myoglobin sequence standard (I don't have the
>catalog at home but it's the more expensive one). Make a reasonable
>concentration solution (e.g. 10-100 pmol/uL, you can always dilute further)
>of each protein sample and aliquot it in 10-20 uL volumes and freeze the
>little tubes. This is a rather tedious process since each SIGMA vial
>contains enough sample to fill many dozens of tubes, but you only have to
>do it once in a great while and you will have perfectly good standards for
>a long time, since degradation and contamination are introduced and
>accelerated by multiple freeze/thaw cycles. The frozen samples (-20oC is
>fine), on the other hand, will last for months or years, at least for mass
>spectrometric purposes. Same procedure for peptide samples.
>Ioannis Papayannopoulos
>AstraZeneca
>(Still in) Worcester, MA
>Bill,
>
>They've always worked fine for me.
>
>Regards,
>Damon
>If you want two standards for the price of one,I always found at least 10%
>BSA dimer.
> And,of course,you can get better material elsewhere,but it would cost
>you.I,always tried
>to purify my own.
>
>We just found out about a great list of peptide, protein, and CHO
>standards. The tables list the source, mass, and company where the
>standards can be purchased. These lists were prepared by Thermo
>BioAnalysis Ltd. and brought to our attention by LeeAnn Higgins.
>
>See:
> http://www.maldi.com
>
>and request Application Note 9 "Recommended Mass Calibrants for Matrix
>Assisted Laser Desorption Mass Spectrometry"
>
>-Lowell H. Ericsson, Dept. of Biochemistry, U. of Washington, Seattle, WA
>
>P.S. For many years we have used apomyoglobin from horse skeletal muscle
>from Sigma as our principle checking standard which we dissolve in 5% HAc,
>50% MeOH. Cat# A-8673. Avg. MW MH+ 16,951.5
>
>Bill:
>
>When you are making the dilutions, make sure you take into account the %
>purity and peptide content that are listed on the vials.
>
>Amina
>
>Amina S. Woods, Ph.D.
>NIDA Intramural Program, NIH
>5500 Nathan Schock Drive
>Baltimore, MD 21224
>Tel: 410-550-1507
>Fax: 410-550-2971
>e-mail: awoods@intra.nida.nih.gov <mailto:awoods@intra.nida.nih.gov>
------------------------------------------------------------------------------
Bill Enslow
Protein Sequencing Technician
Cornell BioResource Center
Rm 143 Biotechnology Building
phone: 607-254-4848
fax: 607-254-4847
----------------------------
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