Peptide Reference Desk
Acyl-ghrelin vs des-acyl ghrelin: the sample can change before it reaches the instrument
Ghrelin acylation is labile. Collection, acidification, esterase control and assay cross-reactivity can determine whether a result reflects biology or handling.
The octanoyl group defines the canonical receptor agonist
Ghrelin is acylated at Ser3, typically with an octanoyl group installed by GOAT. This modification is required for high-affinity activation of GHSR1a. Des-acyl ghrelin lacks that acyl group and should be treated as a distinct analyte, not merely degraded noise.
Preanalytics can dominate the result
The ester linkage is labile and circulating esterases can deacylate ghrelin after collection. Tube type, temperature, time to centrifugation, esterase inhibitor, acidification and freeze-thaw history should be recorded. Without them, inter-study concentration comparisons are fragile.
| Reported value | Question to ask |
|---|---|
| Total ghrelin | Which molecular forms does the assay recognize? |
| Acyl-ghrelin | How was ex-vivo deacylation controlled? |
| Des-acyl ghrelin | Was it present in vivo or formed during handling? |
| LC-MS result | Were recovery and adsorption validated? |
Research-material qualification
A ghrelin lot needs confirmation of sequence, Ser3 acylation, C-terminal state, intact mass, purity and net content. An unmodified peptide cannot be described simply as “ghrelin” when the intended receptor assay depends on acylation.
Verify with primary records
Use the primary paper, current regulator label or lot-linked analytical file for the claim it supports. A search result is a route to evidence, not the evidence itself.