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
At 15:12 02/08/00 -0500, you wrote:
>To the mass speccers,
> We just got a new MALD/I and a new LC ion-trap. I am going to
>purchase the standards apomyoglobin, cytochrome c, melittin, BSA and
>angiotensin 1. I was going to purchase them from Sigma. Has anyone has a
>bad experience (degredation, contamination, etc,) with Sigma proteins as
>standards? Is there a better place to get them?
>Thanks for your wisdom,
>Bill
>
>---------------------------------------------------------------------------
--- >Bill Enslow >Protein Sequencing Technician >Cornell BioResource Center >Rm 143 Biotechnology Building >phone: 607-254-4848 >fax: 607-254-4847 >---------------------------- > > > >__________________________________________________ Do You Yahoo!? Talk to your friends online with Yahoo! Messenger. http://im.yahoo.com
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