Biochemistry & protein chemistry

Through its long term experience with natural compounds and in vivo metabolic studies, Atheris has gained a solid expertise in a wide range of protein chemistry applications. We have proven know how in the extraction, isolation and purification of minute amounts of biomolecules (such as peptides and proteins) from complex mixtures (such as human blood plasma or animal venoms). We like to characteize the molecular structure of these compounds, to synthesize them and to modify them for an improved quality of the end product. We have built up our analytical facilities around our expertise. Our favorite techniques include: 

Top of page

Sample handling

Pre-analytical sample preparation is crucial. It often determines the success or not of an analytical process. Atheris has built a long term know how in this domain, based on a multitude of approaches:

• Extraction : Solid, liquid and gas phase.
  
  
• Separation: Precipitation, dialysis, filtration, ultrafiltration, depletion.
  
  
• Fractionation : Liquid chromatography, electrophoresis.
  
  
• Drying: Freeze-drying and Speed-Vac concentration.
  
  
• Dispensing: Fully robotized liquid handling and sample spotting.
  
  
• Packaging: Conditioning, from single to multi-thousand samples.
  
  

Top of page

Isolation & purification

We are nicely equipped for nano- to preparative-HPLC and FPLC, immuno- and affinity-purification. A multitude of parameters can be investigated, such as the choice of the stationary phase, size of column, size of particles, flow-rate, temperature, solvents, gradient, pH, etc... Based on our many standard operating procedures available at Atheris, we like to undertake method optimization, method validation and process development. We typically use UV-visible (diode array) and mass spectrometers as detectors:

• HPLC: High pressure reversed phase, partition, normal phase, displacement and size exclusion chromatography.
  
  
• FPLC: Low pressure ion exchange, gel permeation, immunoaffinity and bioaffinity chromatography.
  
  

Top of page

Like A Rolling Stone ?

Quality & purity control

We have a broad range of analytical tools to establish certificates of analysis (CoA), which often include matching against a reference sample. Atheris also offers impurities identification, isolation and characterization.

• HPLC: qualitative and quantitative, small to large scale (reversed phase, ion exchange, etc.).
  
  
• Mass spectrometry: ESI-MS, MALDI-TOF-MS, MS/MS, LC-MS, LC-MS/MS (including isotopic resolution).
  
  
• More: UV-VIS spectrophotometry, SDS-PAGE, amino acid composition, Edman sequencing, etc.

Top of page

Quantitative assay

A precise determination of the amount of sample available or its concentration is important, even if it is an impurity present in less than 0.1% amounts or a minor component present in complex mixture. At Atheris we adress this key questions using accurate techniques:

• Classical: UV-VIS, HPLC and of course also by weight using calibrated analytical balances.
  
  
• Mass spectrometry: ESI-MS, LC-MS, MS/MS with external or internal standards.
  
  
• Isotope dilution: the best method is using stable isotope labelled analogue of the target molecule.
  
  
• Protein quantification: amino acid composition, Edman sequencing, Lowry or Bradford assay.
  
  

Top of page

Structural characterization

From simple identity confirmation to complex structural elucidations of complex biomolecules with post-translational modification (disulfide bonds, glycosylation, phosphorylation, acetylation, amidation, etc.):

• Identification: HPLC and MS with database matching.
  
  
• Mass spectrometry: MS, LC-MS, MS/MS, LC-MS/MS, nanoMS/MS.
  
  
• Biochemistry: Mass fingerprinting (MS & MS/MS) following enzymatic or chemical degradation (proteases, glycases, etc.).
  
  
• Chemistry: Edman protein sequencing, de novo MS/MS amino acid sequencing, amino acid composition.
  
  

Top of page

Stability assay

Our analytical equipment, once coupled to our climatic chamber, allows us to conduct stability assays and to identify degradation products under a range of conditions:

• Storage: Absolute and comparative stability towards a range of storage conditions.
  
  
• Temperature: Short, medium and long term temperature stability in solid or liquid form.
  
  
• Freeze-thaw: Resistance to series of freeze-thaw cycles.
  
  
• In vitro: Predictive stability in biological matrices such as plasma or serum.
  
  

This allows us to identify and characterize degradation fragments quite easily at an early stage, which is extremely useful to predict the evolution of a compound in its future environment. These techniques are for example widely used to prepare PK-ADME studies in the frame of pre-clinical studies.

Top of page

Consulting

We also happily assist our partners through consulting agreements in our domains of excellence.

Just contact us!

Top of page