Simple method to prepare non-charged, amphiphilic agarose derivatives, for instance for hydrophobic interaction chromatography

Formation of Amphiphilic Molecules from the Most Common Marine Polysaccharides, toward a Sustainable Alternative?

Marine polysaccharides are part of the huge seaweeds resources and present many applications for several industries. In order to widen their potential as additives or bioactive compounds, some structural modifications have been studied. Among them, simple hydrophobization reactions have been developed in order to yield to grafted polysaccharides bearing acyl-, aryl-, alkyl-, and alkenyl-groups or fatty acid chains. The resulting polymers are able to present modified physicochemical and/or biological properties of interest in the current pharmaceutical, cosmetics, or food fields. This review covers the chemical structures of the main marine polysaccharides, and then focuses on their structural modifications, and especially on hydrophobization reactions mainly esterification, acylation, alkylation, amidation, or even cross-linking reaction on native hydroxyl-, amine, or carboxylic acid functions. Finally, the question of the necessary requirement for more sustainable processes around these structural modulations of marine polysaccharides is addressed, considering the development of greener technologies applied to traditional polysaccharides.

Hydrophobic interaction chromatography of proteins

In this article, an overview of hydrophobic interaction chromatography (HIC) of proteins is given. After a brief description of protein hydrophobicity and hydrophobic interactions, we present the different proposed theories for the retention mechanism of proteins in HIC. Additionally, the main parameters to consider for the optimization of fractionation processes by HIC and the stationary phases available were described. Selected examples of protein fractionation by HIC are also presented.

Chromatography in the downstream processing of biotechnological products

Chromatography techniques are essential for the isolation and purification of most of the high value products of modern biotechnology. The economically sensible and technically satisfactory downstream processing of a therapeutic protein, usually involves a number of chromatographic steps. Its development and optimization require considerable knowledge of the various physico-chemical and engineering aspects of biochemical chromatography. This review addresses the various modes of chromatography and the design of chromatographic separation processes from a biotechnologist's point of view. Strategies for optimizing the structure of the downstream process are outlined and scaling up consideration are discussed. The importance of the different chromatographic methods in research and development is estimated in an analysis of protein purification schemes recently published in the literature. Finally, examples of the application of chromatographic procedures for process scale product purification in the biotechnological industry are given.

Continuous beds. Their applicability for immobilization of proteins

An epoxy-activated continuous bed can be prepared for immobilization of proteins in a simple, rapid, and cost-effective way. The concentration of epoxy groups on the continuous bed was as high as 600 mumol/mL compressed bed (compression of the bed decreases the peak broadening). Human transferrin, human serum albumin and particularly urease were employed as model proteins. The immobilization of urease was virtually completed within 1 h in 1 M potassium phosphate, pH 7.4. The binding capacity was 97 mg of urease/mL compressed bed. This bed is of clinical interest, since it is inexpensive to prepare and permits reproducible enzymatic determination of urea in serum and urine (the chromatographic step is finished within 1-2 min).

Gradient and isocratic high-performance liquid chromatography of proteins on a new agarose-based anion exchanger

We describe a new, simple, and mild method for the preparation of anion-exchangers, based on the coupling of alkylamines to epoxy-activated agarose (prepared by the reaction of agarose with butanediol diglycidyl ether). Since a polar OH-group is formed when an epoxide reacts with an OH or NH2 group, the ion-exchanger did not show any hydrophobic interaction. This is important, since it may be impossible to desorb a protein from an ion exchanger having a hydrophobic character, because increasing the salt concentration of the eluent to decrease the electrostatic binding inevitably strengthens the hydrophobic interaction. By the method described, 3-diethylamino-2-hydroxy-propyl agarose (DEAHP-agarose) was prepared. High resolution of proteins was obtained by gradient elution at both high and low degrees of substitution. However, isocratic separations required a low degree of substitution, in accordance with a hypothesis previously put forward in connection with a theoretical and experimental study of the conditions for isocratic elution of macromolecules on amphiphilic gels. A study of the retention times of several proteins at different pH levels and buffer compositions indicated that different pH levels should be tested for maximal resolution and that, in many cases, the best resolution can be obtained if the DEAHP-agarose is operated in a buffer containing sodium acetate instead of sodium chloride. A quaternary amine agarose, 3-methyldiethylamino-2-hydroxy-propyl agarose (QAE-agarose), can be synthesized easily from DEAHP-agarose by alkylation with methyl iodide. The titration curves of DEAHP-agarose and QAE-agarose showed pK values around 9.5 and 11.3, respectively.