High-level production of recombinant human parathyroid hormone 1-34

Cloning, expression, and purification of porcine adrenocorticotropic hormone in Escherichia coli

Adrenocorticotropic hormone (ACTH) is an old medicine derived from porcine pituitary gland that has been marketed for more than 60 years. In this study, we present a recombinant approach to produce ACTH in Escherichia coli (E. coli). The SUMO-tagged fusion protein was cloned and expressed after induction with isopropyl-β-d-thiogalactopyranoside (IPTG) at 25 °C for 8 h. The fusion protein was extracted and purified by anion exchange chromatography, and the SUMO tag was subsequently removed by digestion with ubiquitin-like protease 1 (ULP1). Approximately 95.3 mg of recombinant ACTH with 94.2% purity was obtained after cation exchange purification performed on a 5 mL column, from 286 mL fermentation broth based on the amount of pellets homogenized. The molecular mass of the recombinant ACTH was confirmed by mass spectrometry to equal 4567.32 Da.

Non-chromatographic purification of Teriparatide with a pH-responsive CspB tag

Cell surface protein B (CspB) from Corynebacterium glutamicum is used as a pH-responsive peptide tag to enable a simple solid-liquid separation method for isolating a CspB fusion protein. Here we demonstrate the first application of a CspB tag for the purification of Teriparatide, which is a biologic drug that is prescribed for osteoporosis. The Teriparatide was constructed as CspB50TEV-Teriparatide, comprising 50 amino acid residues of CspB, the cleavage site of TEV protease, and Teriparatide. CspB50TEV-Teriparatide was expressed in a culture supernatant by C. glutamicum secretion system at 3.0 g/L (equivalent to approximately 1.2 g/L Teriparatide). The CspB50TEV-Teriparatide was precipitated by reducing the pH of the culture supernatant, and the precipitate was then dissolved in a neutral buffer. A TEV protease treatment was applied to cleave the Teriparatide from the CspB50TEV-Teriparatide. Then, the remaining digested CspB50TEV, undigested CspB50TEV-Teriparatide, and TEV protease were precipitated in an acidic pH, whereas the soluble Teriparatide remained in the supernatant. The process had a yield of 96.5% and resulted in Teriparatide with a purity of 98.0% and productivity of 1.1 g/L of C. glutamicum culture. Thus, tag-free Teriparatide was successfully purified from the CspB fusion protein using only pH changes, centrifugation, and protease digestion without the need for chromatography. This versatile purification protocol is expected to be applicable to various proteins from laboratory to industrial scales.

Overexpression of Recombinant Human Teriparatide, rhPTH (1-34) in Escherichia coli : An Innovative Gene Fusion Approach

BACKGROUND

Parathyroid hormone is an 84-amino acid peptide secreted by the parathyroid glands. Its physiological role is maintenance of normal serum calcium level and bone remodeling. Biological activity of this hormone is related to N-terminal 1-34 amino acids. The recombinant form of hormone (1-34) has been approved for treatment of osteoporosis from 2002. In this study, a novel fusion partner has been developed for preparation of high yield recombinant 1-34 amino acids of hPTH.

METHODS

Novel nucleotide cassette designed encoding a chimeric fusion protein comprising of a fusion partner consisting of a His-tag in N-terminal, 53 amino acids belong to Escherichia coli (E. coli) β-galactosidase (LacZ) gene, a linker sequence for increasing of expression and protection of target peptide structure from fusion tag effect, an Enteropeptidase cleavage site, rhPTH (1-34) gene fragment. Optimized fusion gene was synthesized and ligated into pET-28a vector under control of T7 promoter, and then transformed in E. coli (DH5α) cells. Positive clones containing this gene were double digested with NcoI and-BamHI and also approved by sequencing. Gene overexpression was observed in SDS-PAGE after induction with 0.2 mM IPTG. Confirmation of gene expression was performed by western blotting using anti-His-tag antibody conjugated with peroxidase.

RESULTS

By this fusion gene design approach, we achieved a high level expression of the rhPTH, where it represented at least 43.7% of the total protein as determined by SDS-PAGE and confirmed by western blotting.

CONCLUSION

In addition to high level expression of the designed gene in this work, specific amino acid sequence of bacterial β-galactosidase was selected as major part of carrier tag for protection of this hormone as important step of recombinant rhPTH with relevant isoelectronic point (pI). This innovation resulted in recombinant production of hPTH very well and the gene construct could be applied as a pattern for similar recombinant peptides where recombinant protein degradation is a critical issue.

Recombinant production of TEV cleaved human parathyroid hormone

The parathyroid hormone, PTH, is responsible for calcium and phosphate ion homeostasis in the body. The first 34 amino acids of the peptide maintain the biological activity of the hormone and is currently marketed for calcium imbalance disorders. Although several methods for the production of recombinant PTH(1-34) have been reported, most involve the use of cleavage conditions that result in a modified peptide or unfavorable side products. Herein, we detail the recombinant production of (15) N-enriched human parathyroid hormone, (15) N PTH(1-34), generated via a plasmid vector that gives reasonable yield, low-cost protease cleavage (leaving the native N-terminal serine in its amino form), and purification by affinity and size exclusion chromatography. We characterize the product by multidimensional, heteronuclear NMR, circular dichroism, and LC/MS.

A Novel Approach for High Level Expression of Soluble Recombinant Human Parathyroid Hormone (rhPTH 1-34) in Escherichia coli

BACKGROUND

Parathyroid hormone (PTH) secreted by parathyroid glands regulates the metabolism of calcium and phosphorus in bone and kidney. Thereby, it can stimulate bone formation, and is a promising agent in the treatment of osteoporosis. Mature form of PTH consists of 84 amino acids; however, the first 34 residues of PTH cover the majority of hormonal action.

METHODS

In this study, the fusion form of highly soluble rhPTH was expressed at high level in Escherichia coli (E. coli). His6-thioredoxin as an extension for rhPTH improves the solubility of inclusion body. His6-thioredoxin-hPTH (1-34) was ligated into pET32a expression vector. The insertion of 5 amino acids (Asp-Asp-Asp-Asp-Lys) in the N-terminal of PTH made this protein to be digestable specifically by enterokinase enzyme. The fusion form of rhPTH was harvested and purified by immobilized affinity chromatography followed by digestion with enterokinase. Digested rhPTH was purified by applying on size exclusion and ion exchange chromatography to get the highest purity.

RESULTS

The mass spectroscopy analysis shows rhPTH molecular weight was 4117.5 Da. The purity was measured by HPLC column which showed more than 97%. Bioassay analysis of rhPTH was performed on rat sarcoma cell UMR-106 in parallel with commercially available rhPTH, Forteo. The result was measured through immunofluorescence detection kit. The data showed that the potency of rhPTH was comparable with commercially available medicine.

CONCLUSION

Thioredoxin was applied as a fusion partner for production of highly soluble rhPTH. This specific fusion partner increased protein solubility and decreased protease reactivity. Purification process was optimized for high recovery and for purity more than 99%. As its biological activity is comparable with marketed drug, this protein is qualified for biopharmaceutical usage.

Synthesis of ghrelin: chemical synthesis and semisynthesis for large-scale preparation of modified peptides

Most biologically active peptide hormones, including ghrelin, undergo numerous posttranslational modifications and play many crucial roles in nature. Medium- or large-scale preparation methods are required to understand their biological functions and potential applications in life sciences and the biomedical fields. Since ghrelin has an O-acyl modification in its Ser3, recombinant expression for its production has not solely been employed thus far. In this chapter, we provide two distinct protocols for the preparation of human ghrelin: a chemical synthesis method for medium-scale (up to hundreds of milligrams) and a semisynthesis method for large-scale (more than grams) preparation. Established Fmoc chemistry for solid-phase synthesis enables the highly efficient procedure for synthesizing ghrelin in the medium scale. Semisynthesis method, the coupling of chemically synthesized O-acylated ghrelin(1-7) with recombinantly expressed ghrelin(8-28), can be applied for larger scale preparation.

A claudin-4 modulator enhances the mucosal absorption of a biologically active peptide

Biologics, such as peptides, proteins and nucleic acids, are emerging pharmaceuticals. Passage across the epithelium is the first step in the absorption of biologics. Tight junctions (TJ) function as seals between adjacent epithelial cells, preventing free movement of solutes across the epithelium. We previously found that modulation of a key TJ component, claudin-4, is a potent method to enhance jejunal absorption when we used dextran as a model drug and the C-terminal fragment of Clostridium perfringens enterotoxin (C-CPE) as a claudin-4 modulator. Here, we investigated whether the claudin-4 modulator enhances jejunal, nasal and pulmonary absorption of a biologics human parathyroid hormone derivative, hPTH(1-34). The claudin-4 modulator enhanced nasal but not jejunal and pulmonary absorption of hPTH(1-34). C-CPE is hydrophobic with low solubility of less than 0.3mg/ml, but deletion of 10 amino acids at the N-terminal of C-CPE increased its solubility by 30-fold. Moreover, the N-terminal truncated C-CPE bound to claudin-4, modulated the TJ-barrier and enhanced jejunal absorption of dextran. The N-terminal-truncated C-CPE also enhanced jejunal and pulmonary absorption of hPTH(1-34). This report is the first to indicate that a claudin-4 modulator may be a promising enhancer of the jejunal, pulmonary and nasal absorption of a peptide drug.

Semisynthesis of human ghrelin: Condensation of a Boc-protected recombinant peptide with a syntheticO-acylated fragment

The creation of peptide using a combination of recombinant expression and chemical synthesis can be a powerful tool for the production of a wide variety of polypeptides modified by phosphorylation, glycosylation, etc. We have developed a new method for the preparation of a recombinant peptide with a free N(alpha)-amino group and protected N(epsilon)-amino groups, and have used this method in the semisynthesis of human ghrelin. Ghrelin, a natural ligand for growth hormone secretagogue receptor, is a 28-residue peptide with an essential n-octanoyl modification on Ser3. A 7-residue N-terminal fragment of ghrelin containing the octanoyl modification was prepared by Fmoc chemistry. In the preparation of it, all reactions were performed on the 2-chlorotrityl resin. Additionally, TBDMS and tBu turned out to be the most effective protection groups for the Ser3 and the Ser2, Ser6, respectively. For preparation of a 21-residue C-terminal fragment, we established a two-step protease processing method for the partially protected segment. A recombinant precursor peptide was Boc protected and subsequently cleaved using two distinct proteases, OmpT and Kex2. The peptides were then coupled to each other and, after deprotection, resulted in fully active human ghrelin.

Utilization of Escherichia coli outer-membrane endoprotease OmpT variants as processing enzymes for production of peptides from designer fusion proteins

Escherichia coli outer-membrane endoprotease OmpT has suitable properties for processing fusion proteins to produce peptides and proteins. However, utilization of this protease for such production has been restricted due to its generally low cleavage efficiency at Arg (or Lys)-Xaa, where Xaa is a nonbasic N-terminal amino acid of a target polypeptide. The objective of this study was to generate a specific and efficient OmpT protease and to utilize it as a processing enzyme for producing various peptides and proteins by converting its substrate specificity. Since OmpT Asp(97) is proposed to interact with the P1' amino acid of its substrates, OmpT variants with variations at Asp(97) were constructed by replacing this amino acid with 19 natural amino acids to alter the cleavage specificity at Arg (P1)-Xaa (P1'). The variant OmpT that had a methionine at this position, but not the wild-type OmpT, efficiently cleaved a fusion protein containing the amino acid sequence -Arg-Arg-Arg-Ala-Arg downward arrow motilin, in which motilin is a model peptide with a phenylalanine at the N terminus. The OmpT variants with leucine and histidine at position 97 were useful in releasing human adrenocorticotropic hormone (1-24) (serine at the N terminus) and human calcitonin precursor (cysteine at the N terminus), respectively, from fusion proteins. Motilin was produced by this method and was purified up to 99.0% by two chromatographic steps; the yield was 160 mg/liter of culture. Our novel method in which the OmpT variants are used could be employed for production of various peptides and proteins.