Plan around decay
S-35 has a half-life of 87.37 days and loses about 5.4 percent of its activity each week. Ask for the activity you need on the day you start using it.
- 30 days78.8%
- 90 days49%
- 6 months24%
- 1 year5.5%
Unsealed tracers
Feasibility review
Sulfur-35 for research
The label for newly made proteins, G protein activation and sharp autoradiographs.
- Half-life
- 87.37 days
- Beta max
- 167.3 keV
- Decay
- Beta minus to Cl-35
- Exempt quantity
- 100 µCi
S-35 at a glanceIAEA evaluated data
Research applications
Where S-35 does the work.
Figures are simulated examples of each measurement.
Cell biology
Pulse-chase of new proteins2, 3
A short pulse of [³⁵S]methionine and cysteine labels only the proteins a cell makes in those minutes.
More: Pulse-chase of new proteins
A chase with unlabeled methionine then follows that group of proteins as it folds, matures, moves through the cell or is degraded.
In a classic study, only about 25 percent of the newly made precursor of the membrane protein CFTR matured; the rest was degraded with a half-time of about 33 minutes.
Pharmacology
G protein activation4, 5, 6
[³⁵S]GTPγS measures how strongly a ligand activates a G protein-coupled receptor.
More: G protein activation
An activated receptor makes its G protein exchange GDP for GTP. The non-hydrolyzable analog [³⁵S]GTPγS builds up on activated G proteins in cell membranes.
Dopamine raised binding about 62 percent over basal through D2 receptors expressed in CHO cells, and not at all in cells without the receptor.
Neuroscience
In situ hybridization7, 8
³⁵S-labeled RNA probes show where a gene is expressed in tissue sections.
More: In situ hybridization
X-ray film maps the signal across a section in about 1 to 7 days. Photographic emulsion on the slide gives cell-level detail in one to several weeks; a day on film gives about the signal of 5 days under emulsion.
Signal rises linearly with the amount of target mRNA, so sections can be compared quantitatively.
Molecular biology
Sharper autoradiographs9
³⁵S gives sharper bands than ³²P, because its betas travel a shorter distance.
More: Sharper autoradiographs
In dideoxy sequencing, switching the label from ³²P to ³⁵S sharpened the bands and raised the resolution. Exposures ran 1.5 to 2 times longer.
Biochemistry
Cell-free protein synthesis10, 11
[³⁵S]methionine marks the proteins a reticulocyte lysate makes from added mRNA.
More: Cell-free protein synthesis
Nuclease treatment removes the lysate's own mRNA, so it translates only what you add, into full-size products of up to about 200 kDa. The labeled products are read on a gel by autoradiography.
Glycobiology
Sulfation of proteins and proteoglycans12, 13, 14
Cells take up [³⁵S]sulfate and use it to sulfate proteins and proteoglycans.
More: Sulfation of proteins and proteoglycans
Tyrosine sulfation, found in every cell type and tissue examined, is traced this way.
In endothelial cells, 30 mM chlorate cut chondroitin sulfation to 10 percent and heparan sulfation to 35 percent of controls.
Forms
S-35 forms researchers ask for
Every form is confirmed with its manufacturer before you order.
[³⁵S]methionine and cysteine
Labeled amino acids in solution
Metabolic labeling and pulse-chase
Feasibility review[³⁵S]GTPγS
Labeled nucleotide analog in solution
G protein activation assays
Feasibility review³⁵S-labeled nucleotides
For example UTP labeled with ³⁵S, in solution
RNA probes for in situ hybridization
Feasibility review[³⁵S]sulfate
Sodium sulfate in aqueous solution
Sulfation labeling
Feasibility review
Activity, certificate and lead time are set with the manufacturer at quote.
Before you order
Plan for decay and licensing.
Licensing
Exempt quantityNeeds a license100 µCi
A single quantity of S-35 at or below 100 µCi is an exempt quantity under 10 CFR 30.71, Schedule B. Above that, your institution needs a license that covers it.
- Combining exempt quantities to exceed the limit is not covered.
- Sulfur-35 betas travel about 26 cm in air and 0.3 mm in water, so millicurie amounts need no shielding. Liquid scintillation counting is the best readily available way to count its wipe tests.
- Labeled amino acids give off small amounts of volatile ³⁵S, especially when vials are thawed and labeled cultures are incubated. Vent thawing vials in a hood through charcoal, and vent incubated cultures through charcoal filter paper.
- Agreement States apply equivalent rules. Your RSO reviews the exact material before you order.
Start a request
Request a feasibility review for S-35.
No license file needed to ask. A scientist reads every request and replies with the next step.
- Name the compoundGive the labeled molecule, the specific activity and the amount you need.
- Plan for volatilityLabeled amino acids release a little volatile ³⁵S; have a hood and charcoal traps ready.
- Time the experimentActivity halves about every three months.
Decay data
S-35 decay data
Decay schemeS-35 to Cl-35
- Half-life
- 87.37 days ± 0.04
- Decay mode
- Beta minus (100%)
- Daughter
- Cl-35
- Decay energy (Q)
- 167.322 keV
| Radiation | Energy (keV) | Per 100 decays |
|---|---|---|
| Beta | 167.3 max, 48.8 mean | 100 |
Source: IAEA LiveChart of Nuclides, ENSDF evaluation by JUN CHEN and JOHN CAMERON AND BALRAJ SINGH (literature cutoff 20 October 2011), retrieved 25 September 2026 [1]. Reference values; a manufacturer's certificate states the activity of a specific lot.
Questions, answered
S-35 questions
How long does sulfur-35 last?
Its half-life is 87.37 days, so it loses about 5.4 percent a week and about half remains after three months.
Can we buy sulfur-35 without a radioactive materials license?
For small amounts, possibly. A single quantity of S-35 at or below 100 microcuries is an exempt quantity under 10 CFR 30.71, and a distributor licensed under 10 CFR 32.18 can supply exempt quantities to users without a license. Larger amounts need a license that covers them. Your RSO decides how your institution handles each case.
Is labeled methionine volatile?
Slightly. Labeled methionine and cysteine release small amounts of volatile ³⁵S, most when vials are thawed and labeled cultures are incubated. Thaw vials in a hood and trap the vapor with charcoal.
Why use sulfur-35 rather than phosphorus-32 for autoradiography?
Its betas travel a shorter distance, so bands are sharper, and its weaker emission lowers the dose during handling. Exposures take about 1.5 to 2 times longer.
How is sulfur-35 detected?
By liquid scintillation counting, including wipe tests of work surfaces.
Which forms do labs ask for?
[³⁵S]methionine and cysteine for labeling proteins, [³⁵S]GTPγS for G protein assays, ³⁵S-labeled UTP for RNA probes, and [³⁵S]sulfate for sulfation.
More isotopes
Related isotopes
Sources
References
- IAEA Nuclear Data Section. LiveChart of Nuclides, S-35 decay data (ENSDF evaluation). Retrieved 25 September 2026. www-nds.iaea.org/relnsd/vcharthtml/VChartHTML.html
- Simon E, Kornitzer D. Pulse-chase analysis to measure protein degradation. Methods Enzymol. 2014;536:65-75. doi.org/10.1016/B978-0-12-420070-8.00006-4
- Ward CL, Kopito RR. Intracellular turnover of cystic fibrosis transmembrane conductance regulator. Inefficient processing and rapid degradation of wild-type and mutant proteins. J Biol Chem. 1994;269(41):25710-25718. doi.org/10.1016/S0021-9258(18)47306-1
- Harrison C, Traynor JR. The [35S]GTPγS binding assay: approaches and applications in pharmacology. Life Sci. 2003;74(4):489-508. doi.org/10.1016/j.lfs.2003.07.005
- Strange PG. Use of the GTPγS ([35S]GTPγS and Eu-GTPγS) binding assay for analysis of ligand potency and efficacy at G protein-coupled receptors. Br J Pharmacol. 2010;161(6):1238-1249. doi.org/10.1111/j.1476-5381.2010.00963.x
- Gardner B, Hall DA, Strange PG. Pharmacological analysis of dopamine stimulation of [35S]-GTPγS binding via human D2short and D2long dopamine receptors expressed in recombinant cells. Br J Pharmacol. 1996;118(6):1544-1550. doi.org/10.1111/j.1476-5381.1996.tb15572.x
- Simmons DM, Arriza JL, Swanson LW. A complete protocol for in situ hybridization of messenger RNAs in brain and other tissues with radio-labeled single-stranded RNA probes. J Histotechnol. 1989;12(3):169-181. doi.org/10.1179/his.1989.12.3.169
- Chen CC, Wada K, Jarvis ED. Radioactive in situ hybridization for detecting diverse gene expression patterns in tissue. J Vis Exp. 2012;(62):3764. doi.org/10.3791/3764
- Biggin MD, Gibson TJ, Hong GF. Buffer gradient gels and 35S label as an aid to rapid DNA sequence determination. Proc Natl Acad Sci U S A. 1983;80(13):3963-3965. doi.org/10.1073/pnas.80.13.3963
- Pelham HR, Jackson RJ. An efficient mRNA-dependent translation system from reticulocyte lysates. Eur J Biochem. 1976;67(1):247-256. doi.org/10.1111/j.1432-1033.1976.tb10656.x
- Soto Rifo R, Ricci EP, Décimo D, Moncorgé O, Ohlmann T. Back to basics: the untreated rabbit reticulocyte lysate as a competitive system to recapitulate cap/poly(A) synergy and the selective advantage of IRES-driven translation. Nucleic Acids Res. 2007;35(18):e121. doi.org/10.1093/nar/gkm682
- Huttner WB. Sulphation of tyrosine residues: a widespread modification of proteins. Nature. 1982;299(5880):273-276. doi.org/10.1038/299273a0
- Lee RW, Huttner WB. Tyrosine-O-sulfated proteins of PC12 pheochromocytoma cells and their sulfation by a tyrosylprotein sulfotransferase. J Biol Chem. 1983;258(18):11326-11334. doi.org/10.1016/S0021-9258(17)44421-8
- Humphries DE, Silbert JE. Chlorate: a reversible inhibitor of proteoglycan sulfation. Biochem Biophys Res Commun. 1988;154(1):365-371. doi.org/10.1016/0006-291X(88)90694-8
- U.S. Nuclear Regulatory Commission. 10 CFR 30.71, Schedule B (exempt quantities). eCFR, current as of 23 September 2026. www.ecfr.gov/current/title-10/section-30.71
- U.S. Nuclear Regulatory Commission. 10 CFR 30.18, Exempt quantities. eCFR, current as of 23 September 2026. www.ecfr.gov/current/title-10/section-30.18
- University of Wyoming Safety. Nuclide safety data sheet: sulfur-35. www.uwyo.edu/safety/_files/Docs/Procedures/NuclearSafetyDataSheets/35SPDF.pdf
Technical review by ConductScience, 25 September 2026. Next review 25 September 2027.
Need S-35 for a specific instrument or measurement?
Start with what you know. Your RSO and supplier documents come after review. See all radioactive isotopes.
