Are you asking how to search protein databases to find such a protein? If so, you could try EMBOSS:

http://emboss.open-bio.org/rel/dev/apps/emowse.html

This could be used to find the sequence. You could then use other databases to find proteins with the returned sequence and to determine which of these have structures in the PDB

For mass spec databases take a look at the ExPASy site:

http://www.expasy.org/tools/

Hi Neelesh,

Are you interested in many proteins or just a few? A common protein, insulin may fullfill your requirement.  There is also casein.  Both are small proteins insulin specifically is a good one to study cysteine and cysteine derivatizations..

Good luck,

Hediye.

Thanks, Hediye.