[Met5,Lys6]-α-Neo-Endorphin (1-6), also known as Met-Enkephalin-Lys, is a six-residue opioid peptide with the sequence Tyr-Gly-Gly-Phe-Met-Lys. It contains the complete Met-Enkephalin pentapeptide followed by a single C-terminal lysine.

This compact extension provides a useful system for studying how one additional basic residue changes peptide charge, enzymatic processing and opioid-peptide structure–activity relationships without altering the core YGGFM sequence.

Product Information

Met-Enkephalin Core with a Single Basic Extension

The first five residues are identical to endogenous Met-Enkephalin. Addition of Lys6 introduces a positively charged side chain immediately after the opioid pharmacophore while leaving the Tyr-Gly-Gly-Phe-Met sequence intact.

This makes the hexapeptide particularly useful for comparing YGGFM and YGGFMK in receptor, protease and chromatographic experiments.

Peptide Processing Research

Met-Enkephalin-Lys has been identified as an opioid hexapeptide in neuroendocrine tissues. The C-terminal Lys also provides a defined substrate feature for studies examining how basic residues affect processing of enkephalin-related peptides.

It should be treated as its own molecular entity rather than as pharmacologically interchangeable with the five-residue Met-Enkephalin peptide.

Analytical Considerations

Met5 can undergo oxidation during storage or repeated handling. LC-MS can distinguish the intended peptide from methionine-oxidized species.

Researchers can compare the parent pentapeptide on our Met-Enkephalin page.

Frequently Asked Questions

Is YGGFMK the same as Met-Enkephalin-Lys?

Yes. Both names describe Tyr-Gly-Gly-Phe-Met-Lys.

How does it differ from Met-Enkephalin?

It contains one additional C-terminal lysine residue.

Research Use Only.