Publications
1996
A. Štrancar, P. Koselj, H. Schwinn, D. Josić
Analytical Chemistry, Vol. 68, No. 19, October 1, 1996
Production and downstream processing in biotechnology requires fast and accurate control of each step in the process. Improved techniques which can be validated are required in order to meet these demands. For these purposes, chromatographic units containing compact porous disks for fast separation of biopolymers were developed and investigated with regard to their performance and speed. The problems that have, in the past, arisen from the use of wide and flat separation units, such as membranes and disks, have chiefly been those of sample distribution and large void volumes before and behind the unit. Improvements in the construction of the cartridge have led to better performance of the compact porous disks and faster separation. Using these disks, three calibration standard proteins could be separated within less than 1 min by an anion-exchange, cation-exchange, and hydrophobic interaction mode. Such units can be used for in-process control in production and downstream processing of biopolymers, as was shown in experiments involving the purification of α1-antitrypsin and clotting factor IX and the immobilization of enzyme glucose oxidase on an epoxy-activated compact porous disk.
N.I. Dubinina, O.I. Kurenbin, T.B. Tennikova
Journal of Chromatography A, 753 (1996) 217-225
Since the influence of column length on protein resolution in high-performance liquid chromatography (HPLC) is not clear, different viewpoints presented in the literature are analysed in detail. The influence of gradient steepness on the length of the working column part (X0) or the part of a column in which the quasi-steady state is attained was studied. The equation for estimating the X0 value was obtained for the general case of the retention model. It was shown that at steep gradients only a short part of the column is used as the working part on which all separation processes develop. The other part of a column is a ballast where the protein zone migrates in a regime of parallel transfer. These results form a theoretical basis for high-performance membrane chromatography. As was shown experimentally, this method makes it possible to perform protein separation at low gradient times with appropriate resolution, comparable with that of HPLC.
1995
B. G. Belenkii, V. G. Malt'sev
BioFeature, BioTechniques, 288, Vol. 18, No. 2 (1995)
In gradient chromatography for proteins migrating along the chromatographic column, the critical distance X0 has been shown to exist at which the separation of zones is at a maximum and band spreading is at a minimum. With steep gradients and small elution velocity, the column length may be reduced to the level of membrane thickness-about one millimeter. The peculiarities of this novel separation method for proteins, high-performance membrane chromatography (HPMC), are discussed and stepwise elution is shown to be especially effective. HPMC combines the advantages of membrane technology and high-performance liquid chromatography, and avoids their drawbacks.
1994
D. Josić, Y.P. Lim, A. Štrancar, W. Reutter
Journal of Chromatography B, 662 (1994) 217-226
The separation of annexins, calcium-binding plasma membrane-associated proteins from rat liver and Morris hepatoma 7777 by high-performance membrane chromatography (HPMC) is described. The annexins with low molecular masses, CBP 33 and CBP 35, and the annexin with a high molecular mass, CBP 65/67, can be separated within 10 min from one another by anion-exchange HPMC under non-denaturing conditions. The separation devices used consist of compact, porous disks (QuickDisk) on the one hand and of bundled membranes made of cellulose fibers (MemSep) on the other. Both have been found to be equally well suited for this separation. The annexins obtained in this way are subsequently bound to epoxy-activated porons disks and used for the separation of monospecific polyclonal antibodies against the annexin CBP 65/67.
1992
D. Josić, J. Rauch, K. Löster, O. Baum, W. Reutter
Journal of Chromatography A, 590 (1992) 59-76
Porous discs made of poly(glycidyl methacrylate) were used for high-performance membrane chromatography (HPMC) of proteins. In model experiments, separations of standard proteins by anion-exchange HPMC using a DEAE disc were carried out. The influences of sample distribution and disc diameter and thickness on separation performance were studied. The separation disc allowed a scaling-up from analytical (diameter 10 mm) to semi-preparative (diameter 50 mm) dimensions. In an application study, separations with anion-exchange and affinity HPMC were carried out using different complex samples such as rat serum and plasma membrane proteins. In all experiments the results on poly(glycidyl methacrylate) discs were comparable to those achieved on adequate high-performance liquid chromatographic (HPLC) columns. However, the separations on HPMC discs could be carried out faster than corresponding separations on HPLC columns. The pressure drop on the discs was low even at high flow-rates. The experiments show that the poly(glycidyl methacrylate) discs used are especially suitable for the isolation of proteins and other biopolymers which occur in a diluted state in complex mixtures.
1990
T. B. Tennikova, B. G. Belenkii, F. Švec
Journal of Liquid Chromatography, 13(1), 63-70 (1990)
Basing on the fact that only short layers of a chromatographic column contribute to the separation in the interaction chromatography, 1 mm thick membranes from macroporous methacrylate polymer provided with functional groups were synthetized and used for protein separation. The chromatograms show that the separation is fully comparable with that experienced on a filled column but the advantage of a membrane is up to two orders of magnitude lower pressure during the process and very high loading reaching up to 40 g/m2. This recommends the high performance membrane chromatography also for large scale preparative separations.