At 02:04 PM 2/22/01 -0800, Mehrnoosh Sadeghi wrote:
>Hi Trudy,
>
>If the observed peaks are a result of the acidic conditions of sample
>preparation in MALDI, you can probably avoid that by using a
>neutral matrix such as trihydroxyacetophenone (THAP). What
>solvents are you using for the peptide and the matrix? You may
>also be able to use dithranol or 3-indoleacrylic acid, depending on
>your sample? I would give it a try...
>
>Good luck,
>Mehrnoosh
>
>
>________________________________________
>
>From: "Holyst, Trudy" <tholyst@bcsew.edu>
>Subject: PepSyn: Y(NO2)
>Date sent: Thu, 22 Feb 2001 10:10:32 -0600
>To: Recipients of ABRF List <abrf@aecom.yu.edu>
>
>Hi All,
>I have just synthesized two peptides with Fmoc-Y(3-NO2).
>The syntheses
>seemed to go fine and the HPLC tracings showed one
>strong peak but the
>MALDI TOF mass spec of the purified peak showed the
>expected mass plus
>minus 16 and minus 32. Is this an artifact of the mass
>spec? Is the
>nitrate group acid sensitive? I am purifying using RP
>HPLC at pH 2.
>
>Thanks is advance for your thoughts on this.
>
>Trudy Holyst
>Blood Research Institute
>Peptide Core Laboratory
>Blood Center of SE WI
>Milwaukee WI 53201
>
>
>_____________________
>
>Mehrnoosh Sadeghi, Ph.D.
>Stanford Research Systems
>Sunnyvale, CA 94089
>
>
>Trudy:
It is common to lost oxygen on the MALDI TOF for p-nitrophenylanine
peptide. I am sure the same thing happen on the nitro Tyr only lost
additional oxygen.
Alfred Chung
This archive was generated by hypermail 2b29 : Fri Feb 23 2001 - 13:03:34 EST