Creative Proteomics can help you to synthesize peptides or proteins of known primary sequences as mass spec standards, no matter naive or stable isotope labeled ones.
Scientist’s at Creative Proteomics specialized in the custom synthesis of synthetic peptides and peptide based molecules, providing a confidential and efficient service at competitive prices.
more:
http://www.creative-proteomics.com/services/customized-synthesized-peptide-proteins.htm