Thank you for mentioning some of our work. However, to my knowledge, the
availability of the 311-PITC is quite limited and, in the absence of interest
from most sequencer companies, the program has been put in hibernation. This is
quite a shame as this chemistry, while essentially showing the same
characteristics as the regular PITC reagent, offers quite a higher sensitivity
when using a simple ESI-MS system (see my paper in J. Prot. Chem.). What it
would need is: somebody willing to find a straightforward synthesis pathways;
somebody willing to optimize sequencing cycles for this reagent; and somebody
for optimizing the LC/MS conditions. All this have been done in preliminary
experiments and we have shown already in 1995 that, using an old ABI 477 and a
now obsolete LC/MS interface (using a 2.1 mm i.d. column!), we were already
beating by a factor 10 the sensitivity achieved by the PITC reagent by UV
detection. Oh Well.
At this point, it would be unfair not to mention the work of the group of Terry
Lee on the off -line detection of regular PTH amino acids. Since PTH-AAs do not
well ionize using regular solvent, the trick has been to exchange acetic acid
for lithium triflate, for which they claim a sensitivity down to to the
subfemtomole level. Very elegant work.
The complete reference is:
Zhou, J., Hefta, S. and Lee, TD (1997) High sensitivity analysis of
phenylthiohydanthoin amino acid derivatives by electrospray mass spectrometry.
J. Am. Soc. Mass Spectrom. 8(11), 1165-1174.
Hope that it helps
Axel
--------------------------------------------------------------------------------
Axel Ducret, Ph.D.
Senior Research Biologist
Merck-Frosst Canada Inc.
Dept. Biochemistry and Molecular Biology
P.O. Box 1005
Pointe-Claire-Dorval PQ H9R 4P8
Canada
tel. + (514) 428-3428
fax + (514) 428-4900