Three tripeptides contain the same amino acids, but their measured water solubility was far from interchangeable.
What the study actually tested
The researchers compared Ala-Phe-Ala (AFA), Ala-Ala-Phe (AAF), and Phe-Ala-Ala (FAA). Their tests used pure water near pH 6.8 at room temperature, with solubility measured in three independent experiments. Moving phenylalanine to a different position preserved the molecular composition but altered the solid-state packing and the concentration that could remain in solution.
Numbers worth reading in context
| Study measure | Reported result |
|---|---|
| AFA | 672 mM |
| AAF | 105 mM |
| FAA | 42 mM |
The AFA value is about 6.4 times the AAF value and 16 times the FAA value in this experiment. The comparison warns against predicting a peptide’s usable stock concentration solely from its amino-acid count or an average hydrophobicity score. Position and solid-state behavior mattered for these three molecules. It does not prove that rearranging any other sequence will produce the same direction or size of effect.
What to put in the RFQ or experiment plan
For a new sequence, specify the exact residue order in the RFQ and describe the intended solvent, pH, and target concentration. Ask whether a solubility observation was actually measured for that sequence and lot, and what method distinguished a clear-looking dispersion from a true solution. If the protocol requires a concentrated stock, set an acceptable concentration and recovery criterion before ordering.
Evidence boundary
These are published measurements for three small model tripeptides, not NHD batch data or a universal solubility specification. AFA, AAF, and FAA should not be treated as interchangeable products merely because their compositions match.
Sources and next step
Primary research: Solid-state packing dictates the unexpected solubility of aromatic peptides. These external figures are not test results for an NHD lot.
Related NHD guide: read the related article. For a material-specific question, request a written quotation with the sequence, amount, intended use, and required records.
Sources & editorial method
AI-assisted writing and source verification. Numerical claims were checked against the linked full-text records, with source inconsistencies identified in the article. This is not independent scientific peer review or verification of a supplied lot.
1 linked records are listed in the references below. Read the editorial and AI-assistance policy.
How to interpret this article
These are published measurements for three small model tripeptides, not NHD batch data or a universal solubility specification. AFA, AAF, and FAA should not be treated as interchangeable products merely because their compositions match.
Research-use boundary: Catalog materials discussed on this website are for laboratory research, development and manufacturing use only, not for human or veterinary use. This content is not medical advice and does not provide administration instructions.
