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Hydrophobic interaction chromatography (1)
Hydrophobic interaction chromatography (HIC) is used to purify biomolecules like proteins by exploiting differences in hydrophobicity. It works by separating substances based on their varying strength of interaction with hydrophobic groups attached to an uncharged gel matrix. HIC is useful for downstream purification as it can handle large sample volumes with high salt concentrations and is gentler than other methods, maintaining protein activity. Factors like ligand type, salt concentration, pH, and temperature affect HIC separation. The document evaluates HIC for monitoring plasmid DNA purification, finding it is a simple, rapid and reproducible method to assess purity.
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Hydrophobic interaction chromatography (1)
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- 2. ■ Alternatives • Gelfiltration chromatography • Ion exchange chromatography • Reverse phase chromatography Why HIC? • Different basis of separation • Weaker interactions → Less structural damage → Maintain high activity
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- 4. → Purpose → Principleof HIC → Advantages of using HIC → What are the factors affecting HIC → Conclusion Source of protein Extraction Separation Purity & characterization
- 5. ■ Purpose- • Downstreampurification • Separation of biomolecuoles • Exploits differences in hydrophobicity. → Number of hydrophobic aminoacids. → Distribution of these aminoacids.
- 6. Principle • Separation ofsubstances is based on their varying strength of interaction with hydrophobic groups attached to an uncharged gel matrix • Hydrophobic groups on proteins are sufficiently exposed to bind to the hydrophobic groups on the matrix. • How is this achieved? Source of protein Extraction Separation Purity & characterizati on
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- 9. ■ Choice ofcolumn → XK colums for HIC. • Column dimensions → Short bed height (5-15 cm) suitable for HIC ■ Packing of Column: a modern, highly crosslinked agarose-based gel such as Sepharose Fast Flow is however easier than packing a gel filtration column since the bed height required is much smaller. ■ Sample preparation • Sample composition • Sample volume • Sample viscosity ■ Sample application ■ Batch Separation
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- 14. Large volumeof sample can be loaded Samples with high ionic strength can be used Well suited to use before gel filtration, ion-exchange and affinity chromatography Sample eluted with low salt Purification steps that generate large sample volume can be coupled with this method Good for samples after ammonium sulfate fractionation. These techniques may require pretreatment of samples (e.g. reducing ionic strength) Sample can be used in ion exchange chromatography step
- 15. Type and concentrationof ligand Type of base matrix. Type and concentration of salt pH Temperature Additives Effects of ligand density- Degree of substitution ‰ Binding capacity of protein to HIC increases with increased alkyl chain length (A) and increased degree of substitution of immobilized ligand (B) ‰Caution: protein can bind via multipoint attachment, thus difficult to elute
- 16. O CH2 CHCH2 O ( CH2) 3 CH3 OH O CH2 CH CH2 O ( CH2) 7 CH3 OH O CH2 CH CH2 O OH Butyl Octyl Phenyl HIC Ligands
- 17. ‰Important totake note that selectivity will not be exactly the same even with the same type of ligand if the base matrix is different ‰Two widely used supports are cross-linked agarose and synthetic copolymer materials ‰May be necessary to modify adsorption and elution conditions
- 18. Type ofsalt ▪ salt effect follow the Hofmeister series. ▪ Hydrophobic interaction increases at increased salt concentration Increasing salting out effect Anions: PO43- >SO42- >Cl- >Br- >NO3- >ClO4- >I- >SCN- Cations: NH4+ > K+ >Na+ >Li+ >Mg2+ Decreasing surface tension Increasing chaotropic effect Effect of pH on HIC is not straight forward. ‰In general an increase in pH weakens hydrophobic interactions. It could be due to increased titration of charged groups leading to an increase in hydrophilicity of the proteins ‰Decrease in pH leads to an apparently increase in hydrophobic interaction ‰Implication: Important factor to consider for optimization of HIC interaction. It is observed that proteins which do not bind to HIC adsorbent at neutral pH, bind at acidic pH.
- 19. Visser andStrating (1975): that role of temperature is a complex issue and differ from observation of Hierten. ‰ Binding of proteins to HIC adsorbents is entropy driven (Hjerten, 1976), i.e. interaction increases with increase in temperature ‰ Discrepancy in views could be due to differential effects by temperature on the conformational state of different proteins and solubility in solution ‰ Practical terms: To be aware that procedure developed at room temperature may be different if used in the cold room Salts that cause “salting- in” will weakenprotein- ligand interactions. ‰Alcohols and detergents (non-polar parts) can compete with protein for HIC absorbent sites and may displace proteins.
- 20. 1.HIC in combinationwith ammonium sulphate precipitation Crude purification of human autotaxin HIC was used for initial purification of autotaxin, a human 125K protein which stimulates tumour cell motility (49). 2. HIC in combination with ion exchange chromatography Purification of recombinant HIV reverse transcriptase Purification of mammalian transcription factors Micropurification of a GTPase activating protein 3. HIC in combination with gel filtration A major advantage with adsorption chromatography is the possibility to achieve a decrease in sample volume concomitant with an increase in purity. In a purification scheme, HIC and other adsorption chromatography techniques are therefore frequently used prior to gel filtration, in which sample volume is limited. 4. HIC as a ‘‘single step’’ purification technique
- 21. 5.Other HIC applicationareas in the research laboratory HIC using Phenyl Sepharose CL-4B has been used for exchange of protein-bound detergent (54). Octyl Sepharose CL-4B has been used for the separation of different forms of dermatan sulphate proteoglycans (55). HIC of nucleic acids, viruses and cells has also been described. 6. Preparative, large scale applications Purification of a monoclonal antibody for clinical studies of passive immunotherapy of HIV- 1. Purification of recombinant human Epidermal Growth Factor (h-EGF) from yeast. Purification of a monoclonal antibody for in vitro diagnostic use. Purification of a recombinant Pseudomonas aeruginosa exotoxin produced in E. coli.
- 22. M.M. Diogoa, J.A.Queirozb, D.M.F. Prazeres (2003, March) Assessment of purity and quantification of plasmid DNA in process solutions using high-performance hydrophobic interaction chromatography Journal: The Journal of Chromatography A
- 23. The purposeof the study is to demonstrate the usefulness of HIC for monitoring the performance of a plasmid DNA isolation process . Many genetic engineering techniques require a highly pure plasmid DNA sample , hence it is important to develop a reliable analytical method for quantification of plasmid DNA and assessing its purity. Quantification of total plasmid DNA in pure solutions is easily accomplished , by spectrophotometry at 260 nm . However a spectrometer cannot be used for the quantification of impure DNA samples Techniques like Agarose gel electrophoresis , capillary electrophoresis and HPLC can be used to measure the purity of the sample , but all these methods have considerable disadvantages Agarose gel electrophoresis is not reproducible ,CE and HPLC are expensive and time consuming .
- 24. The researchersused a a column filled with Sepharose CL-6B gel derivatized with 1,4-butanediol diglycidyl ether.The HIC column was fitted with a HPLC system , to qualitatively and quantitatively analyze the plasmid sample. The column was equilibriated with Tris-Cl buffer (ph 8.0) The technique takes advantage of the more hydrophobic character of nucleic acid impurities (RNA, proteins etc )compared to ds DNA A E coli lysate is injected into the column in two stages : In the first stage . The sample was eluted with no ammonium sulphate added . In the second stage , the sample was eluted with 450 mM and 1050 mM of ammonium sulphate added to the sample . The chromatograms of both the stages were obtained from the HPLC system , the chromatograms were then compared
- 26. The aboveslide shows four chromatograms each representing the resolved components of the E coli lysate. The chromatogram A was obtained during the first stage of the experiment , where the ammonium sulphate concentration was 0 . The components are not properly resolved , and only a single peak is observed . The chromatogram B , C , D were obtained when the ammonium sulphate concentration was 450 mM , 1050 mM and 1.5 M respectively The above mentioned chromatograms show distinct peaks.The first one representing the eluted plasmid DNA ,the remaining representing the impurities eluted out after the ammonium sulphate concentration has been increased Chromatogram D shows the resolved components of the impurities.
- 27. The resultsobtained showed that that HIC can be used as for quantification and purity assessment of a plasmid DNA sample. The method used involved a simple and a rapid (7 Minute long ) procedure for detecting the purity of a Plasmid sample. Results obtained from repeating the experiment several times, showed a standard deviation value of less than 10%,which shows that the results are reproducible. The technique had the ability to handle highly contaminated samples ( <5% of plasmid DNA ) without any pre-treatment such as digestion of high molecular mass RNA
- 28. Very usefultechnique for mAb purification. Mainly used in the third step as a complementary technique to protein A and IEC (in-vivo). HIC can be used in both binding and removal mode. Can be a useful alternative to SEC for aggregate removal. HIC is also very useful for purification of antibodies in 2-step techniques (non-protein A) for in-vitro applications.
- 29. 1. Teachline.Is.huji.ac.il 2.http://www.separations.eu.tosohbioscience.c om 3. www.http://en.wikibooks.org www.biotech.kth.se/courses/gru/courselist/... /ChromMethods.pdf people.virginia.edu/~dta4n/.../Hydrophobic %20Interaction.html www.google.com/patents/US20070037966 www.med.unc.edu/.../... - United States
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Editor's Notes
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- #9 Equilibrate the column and the sample to binding conditions. essak "General" starting point: equilibration buffer 50 mM sodium phosphate with 1-1.5 M ammonium sulphate Buffer choice will be discussed in more detail later 5 to 10 column volumes is normal for equilibration
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- #19 Salts that promote hydrophobic interactions are known as kosmo or lyotropes and are found to the left in the Hofmeister series. The chemical basis for the Hofmeister ranking reflects a balance between the effects of a given salt´s component ions on water structure and their interaction with protein surfaces. Salting-out ions increase order in water structure, making solubilization water less available. This effect is equated with increased surface tension and favors entropic association of protein hydrophobic residues with immobilized hydrophobic ligands. The most commonly used salt in HIC is (NH4 )2SO4 but other salts like Na2SO4 (sodium sulfate) and NaCl are often used when modifications in binding strength are desirable. Ammonium sulfate is the binding salt most frequently used and has an exceptional solubility (not sodium sulfate). Its major limitation is that above pH 7.5, strongly basic free ammonia can cause denaturation of some proteins and can also cause instability of buffer pH. At elevated pH, use potassium phosphate. The use of NaCl is limited to strongly hydrophobic proteins, on strongly hydrophobic ligands and even then only at very high salt concentrations. By varying both the type of salt and the concentration, good separation may be achieved over a wide range. The concentration of salt is very important. By choosing the right concentration the product may be bound to the matrix while most of the contaminants pass through the column.
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