Re: Protein Sequencing and MS
Jeffrey A Kowalak (jkowalak@codon.nih.gov)
Fri, 27 Feb 1998 15:38:42 -0500
Hi Everybody,
I was going to let Jim's MS baiting slide by, but after Roland's
solid rebuke and other thoughful replies (notably Joe's and Laurey's), I
thought I'd add my $0.02. When I was a post-doc in Ken Walsh's group, I
found an unusual posttranslational modification in ribosomal protein S12
from E coli (see Protein Science 5:1625-1632; 1996). It is important to
note that some top notch protein chemists worked on this protein for YEARS
and still couldn't identify the mod.
Santosh Kumar (Ken's resident Edman expert) was so kind as to run my
peptide, the modified residue eluted with as Asn. But the MS data
(including PSD) indicated an increase of + 46Da. With some clever
suggestions from Ken, we cracked this problem in very short order. My
point, in case you're looking for it, is that Edman chemistry doesn't
always get the job done. Neither does mass spec. Bottom line? As Joe
pointed out, why not use both, solve your nasty little problems and get on
with life.
Warmest Regards,
Jeff Kowalak
PS: A dozen roses to Laurey Steinke for suggesting that people hire mass
spec experts! The MS gods are smiling on you.
Jeffrey A Kowalak, Ph.D.
jkowalak@codon.nih.gov
Section on Metabolic Analysis and Mass Spectrometry
National Institute of Child Health and Human Development
Building 10 Room 9D52
Bethesda MD 20892-1580
telephone: 301-594-3678
facsimile: 301-480-5795