LY3298176 Reference
Written by the Pure Peptides editorial team
Molecular Profile
Compound
LY3298176
Also known as
Pure-TRZ-2
CAS number
2023788-19-2
Molecular formula
C225H348N48O68
Molecular weight
4813.5 g/mol (average)
Amino acid sequence
Y-Aib-E-G-T-F-T-S-D-Y-S-I-Aib-L-D-K-I-A-Q-K*-A-F-V-Q-W-L-I-A-G-G-P-S-S-G-A-P-P-P-S-NH2 (39 residues)
Side-chain modification
lysine 20 carries two AEEA units, then γ-glutamic acid, then eicosanedioic acid
Purity
99%
Physical form
Lyophilized powder
What LY3298176 is, structurally
LY3298176 is a 39-residue peptide with a C-terminal amide, two alpha,alpha-disubstituted residues, and a fatty-acid chain attached through the side chain of lysine 20. The fatty acid governs its handling.
The specification holds up to independent checking. Rebuilding the formula from the stated sequence and modifications gives C225H348N48O68 at 4813.5, matching the stated figures, and the deposited record for this CAS agrees. The nitrogen count reconciles separately: 39 backbone nitrogens (38 peptide-bond amides and the free N-terminal amine), one C-terminal amide, five on side chains from two lysines, two glutamines and one tryptophan, and three in the side-chain linker, one for each AEEA unit and one for the gamma-glutamic acid. That is 48, as stated.
Aib sits at positions 2 and 13. Each bears two substituents on the alpha-carbon rather than one, so neither has an alpha-hydrogen. That matters because base-catalyzed epimerization proceeds by abstracting exactly that hydrogen, so these positions cannot racemize. Carrying two identical methyls, Aib has no alpha-carbon stereocenter at all. Both positions also restrict backbone rotation.
The acyl chain is the dominant fact. A twenty-carbon diacid, joined through gamma-glutamic acid and two AEEA spacers to the lysine side chain, gives an otherwise hydrophilic peptide a long hydrophobic tail, and amphiphiles do not behave in solution as peptides do. The two spacers hold the tail further from the peptide body than a single spacer would.
Three consequences follow. Amphiphiles aggregate above a threshold concentration, so a concentrated stock and a dilute working solution may differ in what they contain. A hydrophobic tail partitions onto plastic and glass, so losses at low concentration can be substantial rather than a trace. And the diacid's far end matters: only one of its two carboxyls forms the amide to gamma-glutamic acid, leaving the other free and negatively charged at neutral pH, and the gamma-glutamic acid keeps a free carboxyl of its own. Added to the two aspartates and the glutamate in the sequence, that makes the molecule distinctly acidic, so solubility improves toward neutral and mildly alkaline pH.
The weak points are visible in the sequence. The single tryptophan is the most oxidation-prone residue present, and two tyrosines add further such positions. Two glutamines can deamidate to glutamate, adding about one mass unit each. There is no cysteine and no methionine, so no disulfide chemistry and no sulfoxide route.
Structure at a glance
Pure-TRZ-2: C 225, N 48, O 68.
Drawn from the product database.
Reconstitution and handling
Sterile water is the usual starting solvent, and neutral to mildly alkaline buffers suit an acidic, acylated peptide. Dilute acid, which helps many peptides dissolve, works against this one.
Add diluent slowly down the inside wall of the vial and swirl gently. Do not vortex; a surface-active molecule foams readily, and foam is an air-liquid interface rather than a cosmetic problem.
Use low-binding tubes and keep transfers few, for the reason above.
No reducing agent is needed, since the formula contains no sulfur.
This is laboratory preparation chemistry, not dosing, administration, or protocol guidance of any kind.
Storage and stability
Store the lyophilized powder at -20 degrees C, sealed, desiccated and protected from light, and let a cold vial warm before opening. Reconstituted, hold at 2 to 8 degrees C, or aliquot and freeze rather than thawing repeatedly.
Tryptophan oxidation is the first named liability, with the two tyrosines behind it; air, warmth and light accelerate all three. Glutamine deamidation is the second, needs water, and is accelerated by warmth and alkaline pH, which argues against holding solutions alkaline for long.
Aggregation deserves separate mention because it is physical rather than chemical and no mass measurement reports it. Associated material may not redisperse on dilution, and freeze-thaw promotes it, which is the practical reason to aliquot on first reconstitution.
These are storage conditions for the material, not dosing or administration guidance.
How LY3298176 is tested
Reversed-phase HPLC establishes chromatographic purity as area percent, and the acyl chain shifts expectations. A twenty-carbon tail retains strongly on a C18 column, so a higher organic proportion is needed than for an unmodified peptide of this length.
Detection sits near 214 nm, and the tryptophan and two tyrosines give good absorbance near 280 nm.
Area percent is a chromatographic measure, not peptide content by weight: water and counter-ions also add to the weight of the powder.
Mass spectrometry confirms identity against 4813.5. At this size average and monoisotopic figures differ appreciably, so establish the reporting basis before comparing against the label. Sixteen units indicates oxidation, most likely at the tryptophan, and one unit deamidation; loss of the acyl side chain would be far larger.
These describe general methodology, not a claim about any particular batch.
Handling FAQ
Why do low-binding tubes matter more for this compound than for an ordinary peptide?+−
Because of the fatty-acid chain. A long hydrophobic tail partitions onto plastic and glass, so at low working concentration the loss can be a large fraction rather than a trace.
Which residue is most likely to oxidize?+−
The tryptophan. It is the most oxidation-prone residue present, so a sixteen-unit mass increase should be read with that position in mind first, ahead of the two tyrosines. Full specifications for Pure-TRZ-2.
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