Search

A cation exchange matrix with zwitterionic and multimodal properties was synthesized by a simple reaction sequence coupling sulfanilic acid to a chitosan based support. The novel chromatographic matrix was physico-chemically characterized by ss-NMR and ζ potential, and its chromatographic performance was evaluated for lysozyme purification from diluted egg white. The maximum adsorption capacity, calculated according to Langmuir adsorption isotherm, was 50.07 ± 1.47 mg g -1 while the dissociation constant was 0.074 ± 0.012 mg mL -1 . The process for lysozyme purification from egg white was optimized, with 81.9% yield and a purity degree of 86.5%, according to RP-HPLC analysis. This work shows novel possible applications of chitosan based materials. The simple synthesis reactions combined with the simple mode of use of the chitosan matrix represents a novel method to purify proteins from raw starting materials. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 34:387-396, 2018., (© 2017 American Institute of Chemical Engineers.)

Casein glycomacropeptide (CMP) is a 64- amino acid peptide found in cheese whey, which is released after κ-casein specific cleavage by chymosin. CMP lacks aromatic amino acids, a characteristic that makes it usable as a nutritional supplement for people with phenylketonuria. CMP consists of two nonglycosylated isoforms (aCMP A and aCMP B) and its different glycosylated forms (gCMP A and gCMP B). The most predominant carbohydrate of gCMP is N-acetylneuraminic acid (sialic acid). Here, we developed a CMP purification process based on the affinity of sialic acid for wheat germ agglutinin (WGA). After formation of chitosan beads and adsorption of WGA, the agglutinin was covalently attached with glutaraldehyde. Two matrices with different WGA density were assayed for CMP adsorption. Maximum adsorption capacities were calculated according to the Langmuir model from adsorption isotherms developed at pH 7.0, being 137.0 mg/g for the matrix with the best performance. In CMP reduction from whey, maximum removal percentage was 79% (specifically 33.7% of gCMP A and B, 75.8% of aCMP A, and 93.9% of aCMP B). The CMP was recovered as an aggregate with an overall yield of 64%. Therefore, the matrices developed are promising for CMP purification from cheese whey. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 33:171-180, 2017 [ABSTRACT FROM AUTHOR]

• Equine chorionic gonadotrophin (eCG) was purified by affinity chromatography. • Wheat germ agglutinin was immobilized on chitosan mini-spheres and used as ligand. • Equine plasma pre-treatment was not needed for eCG adsorption. • The matrix allowed an overall yield of around 60% in one-step purification. Equine chorionic gonadotrophin (eCG) is a hormone widely used in superovulation protocols because of its follicle-stimulating action, which increases reproductive efficiency in animals of productive interest. It contains 45% carbohydrate, 10% of which is N-acetylneuraminic acid (sialic acid). The eCG purification procedures from equine serum or plasma are mainly based on chromatographic methods. However, before these procedures, it is necessary to follow sample pre-conditioning steps, such as several precipitation stages and/or ultrafiltration/diafiltration processes. In this work, an efficient affinity chromatographic matrix for eCG purification directly from plasma was developed. The matrix consisted of chitosan mini-spheres with immobilized wheat germ agglutinin (WGA). The matrix allowed 98% adsorption of eCG directly from plasma without any pre-treatment with an overall yield of around 60%. The matrix chosen was able to maintain the efficient performance of the purification process for three consecutive cycles. Also, the process was scaled-up 500 times in volume and tested over seven consecutive cycles maintaining its chromatographic performance. The results presented here suggest the potential application of this matrix to one-step purification of eCG from plasma. [ABSTRACT FROM AUTHOR]

• Chitosan mini-spheres (CMS) with immobilized Orange R-HE dye as affinity ligand were successfully prepared. • CMS-Orange R-HE were physico-mechanically characterized. • Lactoperoxidase (LP) and lactoferrin (LF) showed affinity for CMS Orange R-HE. • Simultaneous adsorption of LP and LF directly from dairy whey was accomplished. • A differential elution process for LP and LF using Response Surface Methodology was developed. Lactoperoxidase (LP) and lactoferrin (LF) are two interesting proteins present in dairy whey due to their antioxidant, anti-inflammatory, antibacterial, antiviral and antifungal properties. LP and LF are traditionally purified using cation-exchange chromatography, but since the concentration of these proteins in sweet whey are very low (0.03–0.06 g/L for LP and around 0.08–0.20 g/L for LF), clarification, diafiltration, concentration and/or depletion of others whey proteins prior to the ion-exchange chromatography is needed to obtain good adsorption yields. After their elution from the matrix, the overall process results in variable yields. Due to their similar physico-chemical properties, a high cross-contamination is usually present, especially for the LP fraction, where part of the LF is co-eluted. The development of novel supports with immobilized affinity and/or multimodal ligands aims to the direct adsorption of the target proteins even at low concentration and without the need of a pre-treatment of the source. Herein, a new, low-cost support material using chitosan mini-spheres with Orange R-HE triazine dye as immobilized ligand (CMS-Orange R-HE) was synthesized, physico-mechanically characterized and used for the purification of LP and LF by a one-step direct adsorption from dairy whey and a two-step elution process, with minor cross-contamination. CMS-Orange R-HE matrix showed a compression modulus of 47.6 ± 9.8 kPa, predominantly elastic deformation and an open-porous structure with mesopores around 5–20 nm and without ink-bottle pores, ideal for protein purification applications. The affinity between LP and LF for CMS-Orange R-HE matrix was characterized using the Langmuir isotherm model (K d = 0.48 ± 0.07 mg/mL and 0.31 ± 0.09 mg/mL; qmax = 77.5 ± 4.0 mg/g and 56.0 ± 2.1 mg/g, respectively). Adsorption studies showed that LP interaction with CMS-Orange R-HE was partially influenced by the presence of ionic strength (p < 0.05), whereas LF adsorption was not. These differences of both electrostatic and hydrophobic interactions between LP and LF with the CMS-Orange R-HE matrix were used to develop a differential elution process using Response Surface Methodology (RSM). By one-step direct adsorption from dairy whey and two differential elution steps –by using the CMS-Orange R-HE matrix- LP and LF were obtained with good yields (≈70% for LP and ≈60% for LF), high purity and with minor cross-contamination between them. The strategy presented here, could be applied in other cases of cross-contamination between two proteins, being especially interesting for its application in multimodal chromatography. [ABSTRACT FROM AUTHOR]