> I've justed started working with a PerSeptive Biosysmtems Mariner
> ES-TOF instrument. I am getting good strong signals with Bradykinin,
> but when I move to larger molecules (insulin, ubiquitin, myoglobin) I
> am not getting any signal. I am doing a (20ul) loop injection with
> 20pmol/ul protein concentration for all species; this seems like
> plenty of protein. The mobile phase I am using in 5mM ammonium
> acetate, pH 6.0. This is my first forey into the land of ES (been
> using MALDI for a few years) so I am feeling my way around.
>
> Curious if anyone else is using the Mariner for looking at proteins in
> the range of 5-20 kDa, and what your success is, or if you may have
> any tips.
>
> Thanks.
>
> Mike Curtis
> Biotechnology Development
> Bristol-Myers Squibb Co.
> Syracuse, NY
I had a similar problem with a series of experiments I did with Heinrich Roder
on H/D exchange in cytochrome-c. It seems that the spray was very unstable.
With 1mM NH4Ac, pH 4.5, including at least 5% organic solvent (MeOH) gave a
good spray and excellent spectra on our LCQ.
Regards,
-- ________________________________ Steven H. Seeholzer, Ph.D. Staff Scientist Fox Chase Cancer Center 7701 Burholme Avenue Philadelphia, PA 19111phone: (215) 728-1111 fax: (215) 728-3574 email: sh_seeholzer@fccc.edu