Preparation and properties of an alpha-1-protease inhibitor concentrate with high specific activity

Directing membrane chromatography to manufacture α1-antitrypsin from human plasma fraction IV

The surging demand for plasma proteins, mainly driven by the growing market and the development of new therapeutic indications, is promoting manufacturers to improve the throughput of plasma proteins. Due to the inherent convective mass transfer, membrane chromatography has been proved to be an efficient approach for extracting a small amount of target proteins from large-volume feed. In this study, α1-antitrypsin (AAT) was extracted from human plasma fraction IV by a two-step membrane chromatography. An anion-exchange membrane chromatography (AEMC) was used to capture the plasma proteins in bind/elute mode, and the obtained effluent was further polished by a hydrophobic interaction membrane chromatography (HIMC) in flow-through mode. Under optimal conditions, the recovery and purity of AAT achieved 87.0% and 0.58 AAT/protein (g/g) by AEMC, respectively. After the precise polishing by HIMC, the purity of AAT was 1.22 AAT/protein (g/g). The comparison results showed that membrane chromatography outperformed column chromatography in both steps because of its high throughput. This two-step membrane chromatography could obtain an AAT recovery of 83.3% and an activity recovery of 91.4%. The outcome of this work not only offers an alternative process for protein purification from plasma, but also provides guidelines for manufacturing product from a large-volume feed with multi-components by membrane chromatography.

Production, purification, and characterization of human alpha1 proteinase inhibitor from Aspergillus niger

Human alpha one proteinase inhibitor (alpha1-PI) was cloned and expressed in Aspergillus niger, filamentious fungus that can grow in defined media and can perform glycosylation. Submerged culture conditions were established using starch as carbon source, 30% dissolved oxygen concentration, pH 7.0 and 28 degrees C. Eight milligrams per liter of active alpha1-PI were secreted to the growth media in about 40 h. Controlling the protein proteolysis was found to be an important factor in the production. The effects of various carbon sources, pH and temperature on the production and stability of the protein were tested and the product was purified and characterized. Two molecular weights variants of the recombinant alpha1-PI were produced by the fungus; the difference is attributed to the glycosylated part of the molecule. The two glycoproteins were treated with PNGAse F and the released glycans were analyzed by HPAEC, MALDI/TOF-MS, NSI-MS(n), and GC-MS. The MALDI and NSI- full MS spectra of permethylated N-glycans revealed that the N-glycans of both variants contain a series of high-mannose type glycans with 5-20 hexose units. Monosaccharide analysis showed that these were composed of N-acetylglucos-amine, mannose, and galactose. Linkage analysis revealed that the galactosyl component was in the furanoic conformation, which was attaching in a terminal non-reducing position. The Galactofuranose-containing high-mannnose type N-glycans are typical structures, which recently have been found as part of several glycoproteins produced by Aspergillus niger.

Isolation and characterization of alpha1-proteinase inhibitor from common carp (Cyprinus carpio) seminal plasma

Using a three-step procedure, we purified (79 and 51.6-fold to homogeneity) and characterized the two isoforms (a and b) of alpha1-proteinase inhibitor-like protein from carp seminal plasma. The isoforms have molecular masses of 55.5 and 54.0 kDa, respectively. These inhibitors formed SDS-stable complexes with cod and bovine trypsin, chymotrypsin and elastase. The thirty-three amino acids within the reactive loop SLPDTVILNRPFLVLIVEDTTKSILFMGKITNP were identified for isoform b. The same first ten amino acids were obtained for isoform a, and this sequence revealed 100% homology to carp alpha1-proteinase inhibitor (alpha1-PI) from perimeningeal fluid. Both isoforms of alpha1-PI are glycoproteins and their carbohydrate content was determined to be 12.6 and 12.1% for a and b, respectively. Our results indicated that alpha1-PI is one of the main proteins of carp seminal plasma. Using polyclonal anti-alpha1-PI antibodies, alpha1-PI was for the first time localized to the carp testis. The presence of alpha1-PI in testis lobules and in the area surrounding spermatides suggests that this inhibitor may be involved in the maintenance of testis connective tissue integrity, control of spermatogenesis or protection of tissue and spermatozoa against unwanted proteolysis. Since similar alpha1-PI has been identified in rainbow trout semen it can be suggested that the presence of alpha1-PI in seminal plasma is a common feature of cyprinid and salmonid fish.

Blood protein purification and simultaneous removal of nonenveloped viruses using tangential-flow preparative electrophoresis

Gradiflow is new technology allowing purification of important blood proteins from viral contaminated plasma. Protein purification is based on unique scalable tangential-flow preparative electrophoresis, and is distinct from current technology because protein purification and virus removal are performed in the same step. This one-step removal and purification exploits both the size and charge of target proteins. The medically important blood proteins, immunoglobulin G (IgG) and alpha-1-antitrypsin, were chosen to demonstrate the ability of this process to purify proteins from contaminated plasma. Clearance factors achieved by infectivity assays and polymerase chain reaction (PCR) that meet regulatory requirements demonstrated removal of canine parvovirus (CPV). CPV is a model virus for pathogenic nonenveloped viruses, including parvovirus B19, not adequately removed or inactivated by most processes currently in practice. The recovery of proteins from plasma with high purity, recovery, and function, while simultaneously removing viruses, provides blood products with a level of purity compatible with clinical use more quickly and cheaply than available techniques.

Isolation, characterization, and cDNA sequencing of α-1-antiproteinase-like protein from rainbow trout seminal plasma

Seminal plasma of teleost fish contains serine proteinase inhibitors related to those present in blood. These inhibitors can be bound to Q-Sepharose and sequentially eluted with a NaCl gradient. In the present study, using a two-step procedure, we purified (73-fold to homogeneity) and characterized the inhibitor eluted as the second fraction of antitrypsin activity (inhibitor II) from Q-Sepharose. The molecular weight of this inhibitor was estimated to be 56 kDa with an isoelectric point of 5.4. It effectively inhibited trypsin and chymotrypsin but was less effective against elastase. It formed SDS-stable complexes with cod and bovine trypsin. Inhibitor II appeared to be a glycoprotein. Carbohydrate content was determined to be 16%. N-terminal Edman sequencing allowed identification of the first 30 N-terminal amino acids HDGDHAGHTEDHHHHLHHIAGEAHPQHSHG and 25 amino acids within the reactive loop IMPMSLPDTIMLNRPFLLFILEDST. The N-terminal sequence did not match any known sequence, however, the sequence within the reactive loop was significantly similar to carp and mammalian alpha1-antiproteinases. Both sequences were used to construct primers and obtain a cDNA sequence from liver. The mRNA coding the protein is 1675 nt in length including a single open reading frame of 1281 nt that encodes 426 amino acid residues. Analysis of this sequence indicated the presence of putative conserved serpin domains and confirmed the similarity to carp alpha1-antiproteinase and mammalian alpha1-antiproteinase. Our results indicate that inhibitor II belongs to the serpin superfamily and is similar to alpha1-antiproteinase.

Isolation of alpha-1-antitrypsin from human plasma by partitioning in aqueous biphasic systems of polyethyleneglycol-phosphate

The partitioning of alpha-1-antitrypsin was assayed in biphasic aqueous systems containing potassium phosphate and two polyethyleneglycols of molecular mass 600 and 1000, respectively. In order to isolate the alpha-1-antitrypsin from serum plasma, the partitioning behaviour of human serum albumin, its principal contaminant, was also studied. Several aqueous two-phase systems with different partitioning properties were obtained by varying the PEG1000/PEG600 mass proportion. In systems with PEG1000/PEG600 mass ratio of 8, the optimal difference between the partition coefficients of both proteins was found. Under such conditions, a satisfactory purification was carried out by a three-step extraction procedure. By applying this method the alpha-1-antitrypsin specific activity increased severalfold (nearly 10 times) with a yield of 43%.