Purified protein quantification

Quantification of pure proteins and peptides by amino acid analysis

The most accurate method for protein and peptide quantification is amino acid analysis. The process is quite simple: Hydrolysis of an accurate amount of sample is followed by detection and quantification of individual amino acids. The analysis provides quantitative data for 18 out of 20 amino acids. Tryptophan and cysteine are degraded during the hydrolysis.

Choose your service

Our Fast Protein Analysis Services are without customization. You get quality results in easy to understand standard reports, at fixed prices.

Option 1

Quantification of purified protein or peptide

  • Hydrolysis of protein into free amino acids
  • Quantification of 18 amino acids, accuracy within +/- 10%
  • Calculation of µg protein amount (pmol if protein Mw is provided)
Per sample
Results in 4-8 days
Service includes
  • You provide the protein and its estimated Mw.
  • We perform hydrolysis of the sample into free amino acids.
  • Ion exchange chromatography on an amino acid analyzer.
  • Quantification of 18 amino acids with accuracy within +/- 10%.
  • You receive the report within 4-8 days with the calculated protein content in micrograms and in picomoles.

AAA chromatogram

Our customers typically use this analysis for the following applications:

You can use this service for fast concentration determination of protein stock solutions

Sample requirements

Samples can be submitted in liquid form or as solid material.
Avoid very high salt concentrations. Buffer that contain high amounts of primary amines, e.g. TRIS or glycine, may interfere with the ninhydrin reaction and provide false quantification data of specific amino acids.

Pipette 2-6 µg of liquid material into a 500 µl Eppendorf tube and lyophilize/speed vac it.
Alternatively provide 50-100 microliters (or more) of liquid material at minimum concentration of 0.1 microgram per microliter.
Solid material should be provided in sufficient amount for accurate weighing of samples at Alphalyse (mg material).

Technical details

Sixteen amino acids are quantified – the normal 20 amino acids except tryptophan and cysteine. Asparagine is determined as aspartic acid and glutamine as glutamic acid. The analysis process includes:

  • Protein hydrolysis
  • HPLC analysis
  • Data calculation
  • The Alphalyse procedure is based on the Ph. Eur and USP

The analysis is performed on a BioChrom 30 amino acid analyser by ion-exchange chromatography with post-column derivatization using ninhydrin. All amino acids except Proline (440 nm) are monitored at 570 nm.

Accuracy & Precision
For each batch run we include a duplicate analysis of a NIST BSA quality control standard. The precision should be below 5% and the accuracy within 15%.

Data calculations
A standard amino acid solution is analyzed for each 5 samples, and based on at least two runs, a compensation factor is calculated to correct for ninhydrin activity. Each amino acid in the sample is corrected by this compensation factor.

Have questions? We'd love to help.

We're always eager to help. Please send us your question or request and we will get back to you as soon as possible.

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