Preparation of biologically active monomeric recombinant zebrafish (Danio rerio) and rainbow trout (Oncorhynchus mykiss) recombinant growth hormones.

Fish growth hormones (GHs) play an important role in regulating growth, metabolism, reproduction, osmoregulation, and immunity and have thus garnered attention for their application in aquaculture. Zebrafish GH (zGH) cDNA or rainbow trout GH (rtGH) cDNA was cloned into the pMon3401 vector, expressed in MON105-competent Escherichia coli and purified to homogeneity. Their biological activity was evidenced by their ability to interact with ovine GH receptor extracellular domain and stimulate GH receptor-mediated proliferation in FDC-P1-3B9 cells stably transfected with rabbit GH receptor. The relative affinity of zGH and rtGH, estimated by IC50, was about 38-fold and 512-fold lower, respectively, than ovine GH. This is likely the reason for the low biological activity in cells with rabbit GH receptor, ~ 36-fold lower for zGH and ~ 107-fold lower for rtGH than for human GH. This was not due to improper refolding, as evidenced by circular dichroism analysis. Predicting the activity of fish GHs is problematic as there is no one single optimal in vitro bioassay; heterologous assays may be ambiguous, and only homologous assays are suitable for measuring activity.

Escherichia coli "TatExpress" strains super-secrete human growth hormone into the bacterial periplasm by the Tat pathway.

Numerous high-value proteins are secreted into the Escherichia coli periplasm by the General Secretory (Sec) pathway, but Sec-based production chassis cannot handle many potential target proteins. The Tat pathway offers a promising alternative because it transports fully folded proteins; however, yields have been too low for commercial use. To facilitate Tat export, we have engineered the TatExpress series of super-secreting strains by introducing the strong inducible bacterial promoter, ptac, upstream of the chromosomal tatABCD operon, to drive its expression in E. coli strains commonly used by industry (e.g., W3110 and BL21). This modification significantly improves the Tat-dependent secretion of human growth hormone (hGH) into the bacterial periplasm, to the extent that secreted hGH is the dominant periplasmic protein after only 1 hr induction. TatExpress strains accumulate in excess of 30 mg L-1 periplasmic recombinant hGH, even in shake flask cultures. A second target protein, an scFv, is also shown to be exported at much higher rates in TatExpress strains.

Optimization of a recombinant human growth hormone purification process using quality by design.

This work describes a strategy to optimize a downstream processing of a recombinant human growth hormone (rhGH) by incorporating a quality by design approach toward meeting higher quality specifications. The optimized process minimized the presence of impurities and degradation by-products during manufacturing by the establishment of in-process controls. Capillary zone electrophoresis, reverse phase, and size-exclusion chromatographies were used as analytical techniques to establish new critical process parameters for the solubilization, capture, and intermediate purification steps aiming to maintain rhGH quality by complying with pharmacopeial specifications. The results indicated that the implemented improvements in the process allowed the optimization of the specific recovery and purification of rhGH without compromising its quality. In addition, this optimization facilitated the stringent removal of the remaining impurities in further polishing stages, as demonstrated by the analysis of the obtained active pharmaceutical ingredient.

Expression and rapid purification of recombinant biologically active ovine growth hormone with DsbA targeting to Escherichia coli inner membrane.

This study shows expression of recombinant ovine growth hormone (roGH) and targeting to the inner membrane using signal sequence, DsbA, in Escherichia coli (E. coli) cell. Factors such as temperature, IPTG induction, and expression conditions were studied and show diverse optical density with different media compositions. The optimum expression level of roGH in terrific broth medium was at 25 °C on induction with 20 µM IPTG in early logarithmic phase. SDS-PAGE analysis of expression and subcellular fractions of recombinant constructs revealed the translocation of roGH to the inner membrane of E. coli with DsbA signal sequence at the N terminus of roGH. The protein was easily solubilized by 40 % acetonitrile with ~90 % purity and was identified by Western blot, and analysis on MALDI-TOF/TOF confirmed a size of 21,059 Da. Relatively high soluble protein yield of 65.3 mg/L of roGH was obtained. The biological function of roGH was confirmed by HeLa cell line proliferation. This is the first study describing achievement of biologically active soluble roGH targeted to the inner membrane of E. coli and rapid purification with high yield.

MULTIPLEX PCR ASSAY FOR DETECTION OF HUMAN SOMATOTROPIN AND INTERFERON ALPHA2b GENES IN PLANT MATERIAL.

Using transgenic plants as factories for production of physiologically active human proteins arouses special concern because occasional escape of such transgenes into environment may cause health problems. Creation of plant varieties producing pharmaceutically valuable proteins should be accompanied by development of detection methods suitable for controlling the transgene behavior. Here we describe a multiplex PCR protocol for revealing of two human genes (encoding growth hormone and interferon alpha2b) that have been successfully introduced into plant genomes. The primer pair designed for detection of human growth hormone coding sequence amplifies fragments of different size from the full-length gene in the human genome and the intronless coding sequence usually used for plant transformation. Application of this primer pair may be recommended for ruling out false positive results due to sample contamination with human DNA. Such a control may be useful also in PCR analysis during establishing of transgenic plants carrying genes of human origin.

Recombinant production of biologically active giant grouper (Epinephelus lanceolatus) growth hormone from inclusion bodies of Escherichia coli by fed-batch culture.

Growth hormone (GH) performs important roles in regulating somatic growth, reproduction, osmoregulation, metabolism and immunity in teleosts, and thus, it has attracted substantial attention in the field of aquaculture application. Herein, giant grouper GH (ggGH) cDNA was cloned into the pET28a vector and expressed in Shuffle® T7 Competent Escherichia coli. Recombinant N-terminal 6× His-tagged ggGH was produced mainly in insoluble inclusion bodies; the recombinant ggGH content reached 20% of total protein. For large-scale ggGH production, high-cell density E. coli culture was achieved via fed-batch culture with pH-stat. After 30h of cultivation, a cell concentration of 41.1g/l dry cell weight with over 95% plasmid stability was reached. Maximal ggGH production (4.0g/l; 22% total protein) was achieved via mid-log phase induction. Various centrifugal forces, buffer pHs and urea concentrations were optimized for isolation and solubilization of ggGH from inclusion bodies. Hydrophobic interactions and ionic interactions were the major forces in ggGH inclusion body formation. Complete ggGH inclusion body solubilization was obtained in PBS buffer at pH 12 containing 3M urea. Through a simple purification process including Ni-NTA affinity chromatography and refolding, 5.7mg of ggGH was obtained from 10ml of fed-batch culture (45% recovery). The sequence and secondary structure of the purified ggGH were confirmed by LC-MS/MS mass spectrometry and circular dichroism analysis. The cell proliferation-promoting activity was confirmed in HepG2, ZFL and GF-1 cells with the WST-1 colorimetric bioassay.

Comparative study of surface plasmon resonance, electrochemical and electroassisted chemiluminescence methods based immunosensor for the determination of antibodies against human growth hormone.

An indirect immunoassay format with human growth hormone (hGH) immobilized on the self-assembled monolayer (SAM) modified surface plasmon resonance (SPR) chip has been shown to detect specific anti-hGH antibodies using the combination of three different physical phenomena in the same channel of the SPR analyzer. For the enhancement of analytical signal and sensitivity of the immunosensor horseradish peroxidase (HRP) labeled secondary antibodies, specifically interacting with the formed immune complexes, were used. The electroassisted chemiluminescence (ECL) protocol offered the limit of detection (LOD) as low as 0.061 nM and this result was very similar to that obtained by SPR, which was 0.051 nM. In the case of anti-hGH detection using pulsed amperometry (PA) with 3,3',5,5'-tetramethylbenzidine (TMB) and H(2)O(2) in the electrochemical system the LOD was the lowest - 0.027 nm. Lower reproducibility of the analytical signal and higher limit of detection was observed using cyclic voltammetry (CV) where LOD was 0.056 nM. PA detection shows 1.89, 2.07 and 2.26 times higher sensitivity if compared with SPR, CV and ECL, respectively. This work demonstrates successful simultaneous exploitation of several techniques to detect the specific anti-hGH antibodies using indirect immunoassay format on the same area of the SPR-chip.

Cell signaling analysis by mass spectrometry under coculture conditions on an integrated microfluidic device.

A microfluidic device was integrated in a controlled coculture system, in which the secreted proteins were qualitatively and semiquantitatively determined by a directly coupled mass spectrometer. PC12 cells and GH3 cells were cocultured under various conditions as a model of the regulation of the organism by the nervous system. A micro-solid phase extraction (SPE) column was integrated in order to remove salts from the cells secretion prior to mass spectrometry detection. A three layer polydimethylsiloxane (PDMS) microfluidic device was fabricated to integrate valves for avoiding contamination between the cells coculture zone and the pretreatment zone. Electrospray ionization (ESI)-quadrupole (Q)-time of flight (TOF)-mass spectrometry was employed to realize highly sensitive qualitative analysis and to implement semiquantitative analysis. Furthermore, cell migrations under various coculture conditions were observed and discussed. The inhibition on growth hormone secretion from GH3 cells by dopamine released from PC12 cells was investigated and demonstrated. Thus, the developed platform provides a useful tool on cell to cell signaling studies for disease monitoring and drug delivery control.

Probing of some compounds as anti-aggregatory additives in the protein refolding process from Escherichia coli inclusion bodies.

Five compounds of different chemical structure were tested for aggregation suppression during the refolding of porcine and mink growth hormones as model proteins from Escherichia coli inclusion bodies by the dilution method. Of all compounds tested in this work, 3-guanidinopropionic acid (GPA) containing a guanidinium group was the most effective additive for aggregation suppression. Anti-aggregatory properties of GPA were compared with the ones of l-arginine.

Purification of recombinant growth hormone by clear native gels for conformational analyses: preservation of conformation and receptor binding.

Most protein preparations require purification steps prior to biophysical analysis assessing protein stability, secondary structure and degree of folding. It was, therefore, the aim of this study to develop a system to separate and purify a protein from a commercially available medicinal product, recombinant human growth hormone (rhGH) and show preservation of conformation and function following the gel-based procedure. The rhGH was run on clear native (CN) gels and recovered from the gels by electroelution using D-Tube Dialyzer Midi under rigorous cooling. Melting point studies indicated preservation of the structural integrity. This finding was confirmed by synchrotron radiation circular dichroism spectroscopy (SRCD) revealing an identical folding pattern for the sample before and after electrophoretic separation and purification. Synchrotron small-angle X-ray scattering (SAXS) indicated that the sample was folded and monomeric, both before and after separation and purification, and that its shape corresponded well to the known crystal structure of GH. Binding properties of rhGH to a receptor-model system before and after clear native electrophoresis were comparable. This analytical and preparative approach to purify and concentrate a protein preserving conformation and function may be helpful for many applications in analytical, protein and stereochemistry.

Elimination kinetic of recombinant somatotropin in bovine.

Bovine somatotropin (bST), also called growth hormone is a protein hormone produced by the pituitary gland and responsible directly or indirectly for various effects on growth, development and reproductive functions. Its recombinant bovine somatotropin form (rbST) is used in dairy cattle to enhance milk production. Even if the effects of treatment with rbST have been largely studied, until now analytical methods able to detect rbST were limited to immunoassays, which suffer from the impossibility to distinguish between the endogenous and the recombinant form. In this study, a sample preparation procedure based on different precipitation steps, extraction on solid phase and enzymatic digestion was used to purify rbST from serum. The detection was performed by liquid chromatography coupled to tandem mass spectrometry in positive electrospray ionization mode (LC-ESI(+)-MS/MS) allowing the unambiguous identification and quantification of rbST in serum. Samples collected from a cow treated with recombinant bovine somatotropin were analysed and for the first time, the elimination kinetic specific to recombinant somatotropin has been characterized in serum. Detection of rbST was possible from 4h 30min to 4 days after administration and concentration was found up to 10ngmL(-1) during the kinetic.

Two novel bovine somatotropin species generated from a common dehydroalanine intermediate.

Under stressed conditions such as prolonged exposure to high pH, the C-terminal disulfide bridge in bovine somatotropin (bST) is susceptible to a base catalyzed beta-elimination reaction. This reaction converts the disulfide bond to a dehydroalanine residue with loss of a sulphur atom. Two altered species were isolated in pure form and determined to be generated from this dehydroalanine intermediate. One is a monomeric lanthionyl bST (L-bST) with a thioether linkage, and the other is an inter-molecular disulfide linked dimer containing a lysinoalanine. These two novel structures were unambiguously determined using various techniques including enzymatic digestion, amino acid sequencing and analysis, and mass spectrometry. The monomeric L-bST was demonstrated to be equipotent to normal bST in a hypox rat assay, thus showing that formation of lanthionine in place of this disulfide bond does not affect it bioactivity.

High-level secretory expression, purification and characterization of Ailuropoda melanoleuca growth hormone in Pichia pastoris.

Growth hormone is one of the most important hormones, which is involved in many reproductive processes of giant panda Ailuropoda melanoleuca. In this study, the mature peptide of A. melanoleuca growth hormone (AmGH) was successfully expressed and secreted in Pichia pastoris under the control of AOX1 promoter. The expression condition for AmGH in P. pastoris, such as the expression time, pH value and methanol concentration in the BMMY were optimized and the AmGH expression level is about 100 mg/L using GS115 recombinant under optimized condition (96 h of 1.5% methanol induction). The secreted nascent AmGH were purified using ammonium sulfate fractionation. The mature AmGH protein exhibited a molecular mass of approximately 22 kDa on SDS-PAGE. This study would provide a new opportunity for large-scale expression and purification of AmGH, which might facilitate studies on the biological activity of AmGH.

Enzyme-linked immunosorbent assay of changes in serum levels of growth hormone (cGH) in common carps (Cyprinus carpio).

The aim of the present study was to purify the common native carp growth hormone (ncGH), produce monoclonal antibodies (mAbs) to common native carp growth hormone (ncGH), and further enhance the sensitivity of enzyme-linked immunosorbent assays (ELISA) for ncGH. Additionally, we investigated changes in serum ncGH levels in carps raised in different environmental conditions. The recombinant grass carp (Ctenopharyngodon idella) growth hormone was purified and used as antigen to immunize the rabbit. The natural ncGH was isolated from the pituitaries of common carp. SDS-PAGE and Western blot utilizing the polyclonal anti-rgcGH antibody confirmed the purification of ncGH from pituitaries. Purified ncGH was then used as an immunogen in the B lymphocyte hybridoma technique. A total of 14 hybridoma cell lines (FMU-cGH 1-14) were established that were able to stably secrete mAbs against ncGH. Among them, eight clones (FMU-cGH1-6, 12 and 13) were successfully used for Western blot while nine clones (FMU-cGH 1-7, 9 and 10) were used in fluorescent staining and immunohistochemistry. Epitope mapping by competitive ELISA demonstrated that these mAbs recognized five different epitopes. A sensitive sandwich ELISA for detection of ncGH was developed using FMU-cGH12 as the coating mAb and FMU-cGH6 as the enzyme labeled mAb. This detection system was found to be highly stable and sensitive, with detection levels of 70 pg/mL. Additionally, we found that serum ncGH levels in restricted food group and in the net cage group increased 6.9-and 5.8-fold, respectively, when compared to controls, demonstrating differences in the GH stress response in common carp under different living conditions.

Distinct human prolactin (hPRL) and growth hormone (hGH) behavior under bacteriophage lambda PL promoter control: temperature plays a major role in protein yields.

When producing recombinant protein for therapy, it is desirable not only to obtain substantial amounts of the protein, but also to make sure that potential contaminants such as inducing agents are not present in the final product. To prevent this, one can use expression systems in which the promoter (lambdaP(L)) is activated by a temperature shift that denatures a repressor (e.g., cIts). In this manner, hGH was successfully expressed and secreted in Escherichia coli periplasm, with specific yields well above 1 microg ml(-1) A(600)(-1), after a temperature shift from 30 to 42 degrees C. However, attempts to express a related hormone, human prolactin, employing the same protocol were unsuccessful, providing 0.03 microg ml(-1) A(600)(-1) at the most. A process is described in which this labile protein is obtained from a cIts(-) strain under optimized temperature condition (37 degrees C). The highest periplasmic secretions of prolactin ever reported were thus obtained: 0.92+/-0.10 microg ml(-1) A(600)(-1) at an optical density of approximately 3 A(600) units in shake flask cultures and approximately 1 microg ml(-1) A(600)(-1), at an OD of 35 A(600) units, via a rapid and flexible batch feed process in laboratory bioreactor. Purified hPRL was monomeric, correctly processed (Mr=22,906), properly folded and bioactive (51.5+/-24.1 IU mg(-1)).

Pichia pastoris expressing recombinant tilapia growth hormone accelerates the growth of tilapia.

Growth manipulation of fish is an important task in aquatic biotechnology. The growth promoting effect of recombinant Pichia pastoris expressing tilapia growth hormone was demonstrated in red tilapia fry (Oreochromis sp.), which were immersed into water containing intact cells of the recombinant yeast. The weight increase of the treated group was 171% relative to the control group after 6 weeks.

Molecular cloning, characterization, and expression studies of water buffalo (Bubalus bubalis) somatotropin.

Cloning, high-level expression, and characterization of the somatotropin (ST) gene of an indigenous Nili-Ravi breed of water buffalo Bubalus bubalis (BbST) are described. Coding, non-coding, and promoter regions of BbST were amplified and sequenced. Sequence analysis revealed several silent and two interesting point mutations on comparison with STs of other vertebrate species. One interesting variation in the BbST sequence was the replacement of a conserved glutamine residue by arginine. A plasmid was also constructed for the production of BbST in Escherichia coli BL21 (RIPL) CodonPlus, under the control of IPTG-inducible T7-lac promoter. High-level expression could be obtained by synthesizing a codon-optimized ST gene and expressing it in the form of inclusion bodies. The inclusion bodies represented over 20% of the E. coli cellular proteins. The biologically active conformation of purified BbST was confirmed by its efficient growth promoting activity in Nb2 cell proliferation assay. The expression system and purification strategy employed promise to be a useful approach to produce BbST for further use in structure-function studies and livestock industry.

Production of recombinant mink growth hormone in E. coli.

Escherichia coli cells expressing mink (Mustela vison) growth hormone were grown in a batch fermentation process. The expression level was estimated to be 27% of the total cellular protein after 3 h of induction with 1 mM isopropyl beta-D-thiogalactoside (IPTG). If the expression of mink growth hormone (mGH) was induced with 0.2 mM IPTG, the concentration of target protein was slightly lower and was found to be 23% at the same time after induction. mGH expressed as inclusion bodies was solubilized in 8 M urea and renatured by dilution protocol at a protein concentration of 1.4-2.1 mg/ml in the presence of glutathione pair in a final concentration of 11.3 mM. [GSH]/[GSSG] ratio equal to 2/1 was used. Two-step purification process comprising of ion-exchange chromatography on Q-Sepharose and hydrophobic chromatography on Phenyl-Sepharose was developed. Some 25-30 mg of highly purified and biologically active mGH was obtained from 4 g of biomass. The method presented in this study allows producing large quantities of mGH and considering initiation of scientific investigation on mGH effect on mink in vivo and availability in fur industry.

Isolation of Atlantic halibut pituitary hormones by continuous-elution electrophoresis followed by fingerprint identification, and assessment of growth hormone content during larval development.

Continuous-elution electrophoresis (CEE) has been applied to separate putative hormones from adult Atlantic halibut pituitaries. Soluble proteins were separated by size and charge on Model 491 Prep Cell (Bio-Rad), where the homogenate runs through a cylindrical gel, and protein fractions are collected as they elute from the matrix. Protein fractions were assessed by SDS-PAGE and found to contain purified proteins of molecular size from 10 to 33 kDa. Fractions containing proteins with molecular weights of approximately 21, 24, 28 and 32 kDa, were identified as putative growth hormone (GH), prolactin, somatolactin and gonadotropins, respectively. These were analyzed further by mass spectrometry and identified with peptide mass protein fingerprinting. The CEE technique was used successfully for purification of halibut GH with a 5% yield, and appears generally well suited to purify species-specific proteins often needed for research in comparative endocrinology, including immunoassay work. Thus, the GH obtained was subsequently used as standards and iodination label in a homologous radioimmunoassay, applied to analyze GH content through larval development in normally and abnormally metamorphosing larvae. As GH is mainly found in the pituitary, GH contents were analyzed in tissue extracts from the heads only. The pituitary GH content increases proportionally to increased larval weight from first feeding to metamorphic climax. No difference in relative GH content was found between normal and abnormal larvae and it still remains to be established if GH has a direct role in metamorphosis.