Elcatonin (CAS 60731-46-6) and calcitonin are frequently mentioned together, but they are not the same molecule. This article explains the structural differences between Elcatonin, natural eel calcitonin and other calcitonin analogues, and why those differences matter in research, stability studies and analytical verification.
What Is the Difference Between Elcatonin and Calcitonin?
Calcitonin is a class of peptide hormones involved in calcium homeostasis, produced in different forms across vertebrate species, including human, salmon, eel and porcine calcitonin.
Elcatonin is a synthetic analogue based on eel calcitonin, with a designed N-terminal modification. The key distinction is structural: in Elcatonin, the native disulfide bridge is replaced by a carbon–carbon linkage in the deamino-dicarba analogue, while natural calcitonin retains the disulfide bond.
The hierarchy is: calcitonin family → eel calcitonin → synthetic analogue → Elcatonin. Natural peptides, synthetic analogues and analogues from different species are not interchangeable research materials; each has a distinct identity, structure and set of analytical requirements.
Structural Comparison: Elcatonin vs. Eel Calcitonin
Both Elcatonin and eel calcitonin are 32-amino-acid peptides with an N-terminal ring structure and a C-terminal amidated region.
The critical difference is in the ring structure:
- Eel calcitonin: disulfide bond between Cys¹ and Cys⁷
- Elcatonin: the native Cys¹–Cys⁷ disulfide bond is replaced by a carbon–carbon linkage in the deamino-dicarba analogue, sometimes described in the literature as an ethylene bridge
This single structural change alters the molecular topology and is the basis of Elcatonin's distinct identity as (Asu¹,⁷)-Calcitonin (eel).
Why Is the Modified Cys¹–Cys⁷ Linkage Important?
Disulfide bonds in peptides can undergo chemical changes under certain redox or stress conditions. The modification in Elcatonin was designed to replace this linkage with a more constrained carbon–carbon connection in the deamino-dicarba analogue.
Published research indicates that this modification can influence molecular conformation and in vitro stability compared with native calcitonin. However, stability findings are condition-specific: results from controlled studies should not be extrapolated directly to finished-product shelf life or clinical performance without product-specific evidence.
Elcatonin vs. Salmon, Human and Porcine Calcitonin
Calcitonin peptides from different species differ in amino acid sequence and receptor-related activity:
| Material | Origin / Identity | Length | Structural feature |
|---|---|---|---|
| Elcatonin | Synthetic analogue of eel calcitonin | 32 aa | Modified Cys¹–Cys⁷ linkage |
| Eel calcitonin | Natural (eel) | 32 aa | Cys¹–Cys⁷ disulfide bond |
| Salmon calcitonin | Natural (salmon) | 32 aa | Disulfide bond, distinct sequence |
| Human calcitonin | Natural (human) | 32 aa | Disulfide bond, distinct sequence |
| Porcine calcitonin | Natural (porcine) | 32 aa | Disulfide bond, distinct sequence |
Sequence differences, receptor studies and conformational research mean these analogues cannot be treated as directly interchangeable materials in experimental work.
How Structural Differences Affect Analytical Characterization
Structural modifications directly affect how the material should be verified:
- Theoretical molecular weight - Elcatonin (3363.77 g/mol) differs from other calcitonin analogues; confirm against the specific grade's documentation
- LC-MS - molecular mass confirmation should match the expected Elcatonin identity, accounting for charge states and ion forms
- HPLC - chromatographic purity under specified conditions, with methods stated
- Salt form - Elcatonin vs. Elcatonin Acetate must be distinguished in specifications and content calculations
Structural verification should be tailored to the specific analogue, not assumed from generic calcitonin documentation.
Why Structural Identity Matters When Sourcing Elcatonin Powder
For research and development buyers, confirming the exact molecular identity is essential before procurement. Elcatonin, eel calcitonin and other calcitonin analogues may share related biological backgrounds but require different specifications, analytical methods and documentation.
Before sourcing, verify:
- CAS number confirmation (60731-46-6)
- Batch-specific COA and specification correspondence
- LC-MS identity data where available
- HPLC purity data with stated method
For a detailed verification framework, see our Elcatonin powder quality verification guide. For Elcatonin Powder specifications and sourcing information, visit the product page.
FAQ
Is Elcatonin a calcitonin analogue?
Yes. Elcatonin is a synthetic analogue of eel calcitonin with a modified N-terminal linkage at positions 1 and 7.
Is Elcatonin derived directly from eel tissue?
No. Elcatonin is synthetically produced. It is structurally derived from eel calcitonin but is not extracted from eel tissue.
What is the role of the Asu bridge?
The Asu modification at positions 1 and 7 replaces the native disulfide bond with a carbon–carbon linkage in the deamino-dicarba analogue, which is the defining structural feature of Elcatonin.
Is Elcatonin more stable than natural calcitonin?
Published studies report differences in in vitro stability and conformational behavior associated with the modification under specific conditions. General conclusions about shelf life or clinical stability require product-specific evidence.
Can Elcatonin replace other calcitonin analogues in research?
Not automatically. Different analogues have distinct sequences, structures and analytical requirements. Equivalence should be established case by case for the specific research application.
Conclusion
Elcatonin is structurally distinct from natural calcitonin and from other species-derived analogues, primarily through its modified Cys¹–Cys⁷ linkage. These differences affect conformational research, stability studies, analytical verification and material selection.
For a basic introduction to the molecular identity of Elcatonin, see our foundational article. For analytical verification guidance, see our Elcatonin powder quality verification guide.
For Elcatonin Powder specifications and sourcing information, visit the product page.
References
Morikawa T., et al. Synthesis of eel-calcitonin and (Asu1,7)-eel-calcitonin: contribution of the disulfide bond to the hormonal activity. Experientia. 1976;32(9):1104-1106.
Japanese Pharmacopoeia. Elcatonin monograph.
PubChem. Compound record for CAS 60731-46-6.