Message-Id: <v03007800af09d1cc4083@[131.215.4.147]>
In-Reply-To: <970120185025_646475662@emout17.mail.aol.com>
Date: Mon, 20 Jan 1997 17:56:58 -0800
From: Gary Hathaway <hathaway@cco.caltech.edu>
Subject: Re: No mass data by MALDI-TOF
To: Recipients of ABRF List <abrf@aecom.yu.edu>
At 4:20 PM -0800 1/20/97, JCaplan339@aol.com wrote:
>Hi,
>
>I have a couple of questions regarding MALDI-TOF. We are using a Finnigan
>LASERMAT 2000 mass spec. and were recently asked to mass a protein with an
>approx. mol. mass of 90 kDa. Using other analytical techniques, the protein
>appears to form multimers (not quite sure of the mechanism) - potentially
>quite large. Our thought was that the monomer form should be able to be
>seen. The matrix used was Sinapinic Acid and the protein was in water. We
>could not see anything with an approximate 10pmol spot. Other amounts were
>used and still nothing could be seen. Does anyone have any suggestions?
> Should I try a different matrix (ACH)?. How large of a protein can one
>typically see using MALDI-TOF?
>
>Does anyone use a LASERMAT 2000? If so, how do you like it and what type of
>error% do you typically see.
>
>Thank you very much,
>
>Jeff (Jeffrey Caplan)
>
>The accompanying eMail address is my home eMail address. My work eMail
>address is Jeffrey_Caplan@Internetmail.PR.Cyanamid.com.
Jeff,
How old is your detector? The higher mass proteins are usually more
difficult to detect than small peptides, and if your detector has been
around for a while, you may just be seeing a loss of sensitivity at high
mass. Can you still get bovine serum albumin at 66K? When my lasermat
detectors were new, I was able to detect the trimer of BSA with my
Lasermat. After about a year, I could not see the monomer. After replacing
the detector, it was good as new.
regards
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Gary M. Hathaway, Director
PPMAL - Protein/Peptide Micro Analytical Laboratory
California Institute of Technology
139-74, Division of Biology
Pasadena, CA 91125
http://www.cco.caltech.edu/~ppmal
email Gary: hathaway@caltech.edu
email facility: ppmal@caltech.edu
phone: lab (818) 395-6388 or office (818) 395-2769
FAX (818) 449-3414
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