Alpha-endorphin

Also known as α-Endorphin; Beta-endorphin (1–16)

The 16-residue N-terminal fragment of beta-endorphin, studied for opioid activity and sequence-dependent changes in peptide pharmacology.

Length: 16 amino acids
Half-life: Not well characterised
Mechanism: Alpha-endorphin retains the N-terminal opioid recognition motif of beta-endorphin and exhibits opioid receptor activity. Its subtype pharmacology is less comprehensively characterised than that of beta-endorphin, so μ- or δ-receptor involvement should be established experimentally rather than assumed.
Studied in: Receptor-binding assays, isolated tissue preparations and rodent behavioural models examine alpha-endorphin's opioid activity and the consequences of beta-endorphin truncation.

About Alpha-endorphin

Alpha-endorphin comprises residues 1–16 of beta-endorphin and has the sequence Tyr-Gly-Gly-Phe-Met-Thr-Ser-Glu-Lys-Ser-Gln-Thr-Pro-Leu-Val-Thr. Its sequence therefore derives from the POMC precursor through the beta-endorphin region of beta-lipotropin. Identified in early investigations of endogenous opioid peptides, it preserves the N-terminal methionine-enkephalin motif while lacking the longer C-terminal portion of beta-endorphin. This makes it useful for examining how chain length affects receptor recognition and susceptibility to proteolysis in controlled laboratory comparisons.

Experimental work on alpha-endorphin includes opioid receptor binding and functional responses in isolated preparations, alongside historical animal studies of behavioural effects. The presence of the opioid motif does not establish selectivity for any single receptor subtype. Modern comparisons benefit from receptor-defined cell systems and antagonist controls rather than relying on behavioural readouts alone. Because alpha-endorphin differs from gamma-endorphin by only one C-terminal residue, analytical identity is particularly important when comparing these closely related fragments.

Laboratory notes

Verify the 16-residue sequence and C-terminal threonine by mass spectrometry; gamma-endorphin contains an additional leucine.
Check for methionine oxidation and truncated impurities before interpreting structure–activity comparisons.
Include beta-endorphin and receptor-selective antagonist controls when assessing opioid-dependent activity.

Storage and reconstitution basics: storage guide.

Questions about Alpha-endorphin

How does alpha-endorphin differ from gamma-endorphin?

Alpha-endorphin is beta-endorphin (1–16); gamma-endorphin is beta-endorphin (1–17) and includes one additional C-terminal leucine.

Is alpha-endorphin simply another name for beta-endorphin?

No. It is a defined N-terminal fragment, with 16 rather than 31 amino acids and a distinct experimental pharmacological profile.

Can receptor selectivity be inferred from its sequence?

The sequence supports opioid receptor recognition, but it does not establish subtype selectivity. Binding and functional assays in receptor-defined systems are needed.

Is Alpha-endorphin for human use?

No. It is supplied strictly for in-vitro laboratory research and is not for human or animal consumption.

Related research peptides

All products are sold for laboratory research use only. Not for human consumption, not a medicine, not for diagnosing, treating or preventing any condition.