Can anyone give me advice on activationg cys on a resin-bound peptide
with SPyr? We have removed Mtt from the Cys with 1% TFA and added 5-10
eq Dithiopyridine in 2-propanol/AcOH (2N), but get little change in
absorption at 343nm (ext. coeff liberated SPyr = 7400 cm-1 M-1). We
tested the reaction with an amount of free H-Cys-OH equivalent to that
in the peptide and the color change was rapid and large. Is the reaction
with resin bound peptide very slow?
Also, what problems can we expect when emoving Acm from a second cys, or
on cleaving the peptide (e.g from scavengers?).
If we carry out the reaction on a free peptide, can we remove residual
SPyr and dithiopyr without having to chromatograph?
Thanks, Alex
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Dr. Alessandro Tossi
Antiinfective peptides group
Dept. of Biochemistry, Biophysics and Macromolecular Chemistry
University of Trieste
Phone -- 39 40 6763673; Fax -- 39 40 6763691
email: tossi@bbcm.univ.trieste.it
http://www.bbcm.univ.trieste.it/~tossi
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