Tanzer F S, Tolun E, Fridland G H, Dass C, Killmar J, Tinsley P W, Desiderio D M
Department of Biologic and Diagnostic Sciences, College of Dentistry, University of Tennessee, Memphis.
Int J Pept Protein Res. 1988 Aug;32(2):117-22. doi: 10.1111/j.1399-3011.1988.tb00671.x.
The presence of the free opioid pentapeptide methionine enkephalin (ME) and of ME-containing peptide(s) was established firmly in decalcified, depulped human teeth by using a combination of methods including RP-HPLC, radioimmunoassay, radioreceptorassay, trypsin, carboxypeptidase B, fast atom bombardment mass spectrometry, and MS/MS methodology. Positive structural identification of ME was made with mass spectrometry. Those data demonstrate the presence of the preproenkephalinergic A system in the human trigeminal sensory termini.