Catalogue / Follistatin
Follistatin
Also written as FS-344, FST.
A glycosylated activin-binding protein expressed in several isoforms of different length, most commonly supplied as FS-344 or FS-315.
| Class | Recombinant proteins |
| Determination | Recombinant protein, content, purity and dimer |
| Price | 650 USD |
Follistatin is identified against a certified reference standard rather than against a published mass, because commercially supplied material varies in composition between suppliers. Purity is reported separately by reversed-phase chromatography at 214 nm and describes the chromatographable fraction only.
| The isoforms differ in length and in glycosylation, so material sold simply as follistatin has no single expected mass. Which isoform was supplied is the first question and is rarely answered on a label. |
| Multiple disulfide bridges must be correctly paired. Misfolded material has the identical mass and different activity, so mass confirmation alone does not establish that the protein is correctly folded. |
| No mass figure is published on this page. Identity is established against a certified reference standard for the stated isoform at the time of analysis. |
Every compound fails in its own way. A generic peptide method applied without regard to these specifics produces a number that looks like a result and is not one.
Expressed rather than synthesised. The failure modes are different: aggregation, deamidation, oxidation and truncation, none of which a single purity number captures.
RP-HPLC purity, size exclusion chromatography for dimer and higher aggregate, and where required a charge-variant separation. Aggregate is reported as a separate figure because a dimer is chemically still the same protein.
Where the delivered milligram figure matters rather than the percentage, net peptide content by combustion analysis and water by Karl Fischer are added, and the certificate carries a closed mass balance instead of a single purity number.
| LC-MS identity | Measured mass |
| RP-HPLC purity | Area at 214 nm |
| Net peptide content | Milligrams |
| Water content | Karl Fischer |
| Counter-ion | Ion chromatography |
| Bacterial endotoxins | USP <85> |
What is the molecular weight of Follistatin?
No molecular weight is published for Follistatin on this page, because the composition of commercially supplied material varies between suppliers and an unverified figure on an analytical site is worse than an absent one. Identity is established against a certified reference standard at the time of analysis.
How is Follistatin tested for purity and identity?
RP-HPLC purity, size exclusion chromatography for dimer and higher aggregate, and where required a charge-variant separation. Aggregate is reported as a separate figure because a dimer is chemically still the same protein. Purity describes the chromatographable fraction only and is not the same quantity as the peptide mass delivered per vial.
What goes wrong when Follistatin is analysed?
The isoforms differ in length and in glycosylation, so material sold simply as follistatin has no single expected mass. Which isoform was supplied is the first question and is rarely answered on a label.
What does Follistatin analysis cost at ANALYTON?
Recombinant protein, content, purity and dimer is priced at 650 US dollars, covering the determinations described on this page. Content, safety and elemental determinations are ordered alongside and are priced separately on the price list.
Other compounds in this class
Updated 2026-09-01. Masses computed at build, not transcribed.