Phospho-tyrosine cleavage

[Nadesalingam N Palaniyar]

Hi netters,

I am looking for an enzyme(s) or chemical(s) that could cleave the 
phospho-tyrosine bond.  This info I am looking for is needed for removing 
a protein covalently bound to the DNA.  This protein presumably binds the 
DNA at the 3'-phosphate through the -OH group in the tyrosine of the 
protein.

Proteinase K treatment leaves a few amino acids at the end, and this 
complicates the mapping (I have selectively labelled the 5' end of the
"cleavage strand").  Labelling the 3'end may not give an accurate mapping, 
since I am using a PCR DNA for my experiment (which may have a 3' tail),  
and also in that case I need the Maxam/Gilbert sequencing ladder for 
the size markers.

I would appreciate any references or suggestions for this phospho-tyrosine 
cleavage problem.

PS:  I have contacted technical service reps in a few companies, and they 
did not have any useful suggestion.

Thanks in advance.

Nades Palaniyar
Dept of Molecular Biology and Genetics
Univ of Guelph