Analysis of isoaspartate in peptides and proteins without the use of radioisotopes.
Schurter. B T BT; Aswad. D W DW
Key Findings
- A rapid HPLC method can detect as little as 5 pmol of isoaspartate in peptides or proteins.
- The assay is linear and stoichiometric from 5 to 250 pmol, linking isoaspartate amount to production of S‑adenosyl‑L‑homocysteine.
- Compared with radioactive methods, the HPLC approach is safer, faster, cheaper, and equally sensitive.
Practical Outcomes
- For biohackers and citizen scientists, this study offers no direct actionable insight for longevity, metabolism, or performance. It is useful only if you are running a laboratory that needs to measure protein aging or damage, not for everyday health optimization.
Summary
The paper describes a lab technique for measuring a tiny chemical change (isoaspartate) in proteins using HPLC, without radioactive materials. It’s a technical method for researchers, not a health‑related finding or a protocol you can apply to diet, supplements, or performance.
Abstract
A rapid and sensitive HPLC-based method for quantitating isoaspartate levels in peptides and proteins is described. The analyte is incubated for 40 min with S-adenosyl-l-methionine and the commercially available enzyme protein l-isoaspartyl methyltransferase. Methylation of isoaspartyl sites results in stoichiometric production of S-adenosyl-l-homocysteine that is separated from the other components of the reaction by reversed-phase HPLC and quantitated online by absorbance at 260 nm. This method can accurately detect 5 pmol or less of isoaspartate and works with tryptic digests as well as intact proteins. Using a commercially available isoaspartyl peptide, the relationship between isoaspartate levels and S-adenosyl-l-homocysteine production was found to be linear and stoichiometric over a range of 5-250 pmol. Compared to methods that measure [(3)H]methanol production after methylation with S-adenosyl-l-[methyl-(3)H]methionine, the HPLC method is safer, faster, less expensive, and equally sensitive.
Study Information
pubmed
2000
2000-07-01T00:00:00.000Z
10.1006/abio.2000.4601