Human growth hormone-specific aptamer identification using improved oligonucleotide ligand evolution method

Çalık, Pınar
Ozdamar, Tuncer H.
LETEG is a method developed and used for the separation and purification of proteins employing a single-step ligand (aptamers) evolution in which aptamers are eluted with an increasing temperature gradient. Using recombinant human growth hormone (rhGH) as the test purification target, and after avoiding cross reactions of aptamers with Bacillus subtilis extracellular proteins by negative SELEX, the effects of time and pH on aptamer binding to rhGH were investigated. The highest binding efficiency of aptamers on rhGH-immobilized microparticles was obtained at pH 7.0. The aptamers that interacted with rhGH were eluted by a multi-stage step-up temperature gradient in Delta T = 10 degrees C increments within the range T = 55-95 degrees C; and the strongest affinity binding was disrupted at T = 85 degrees C where C-Apt = 0.16 mu M was eluted. The equilibrium binding data obtained was described by a Langmuir-type isotherm; where the affinity constant was K-D = 218 nM rhGH. RhGH was separated from the fermentation broth with 99.8% purity, indicating that the method developed is properly applicable even for an anionic protein.


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Foam separation is a simple and economic method for separation of surface-active molecules such as proteins and enzymes from aqueous solutions. In this study, lactic acid broth, spent brewer’s yeast extract and residual beer was used to investigate the applicability and efficiency of foam separation technique in partial purification of fermentation products and recovery of valuable components from industrial waste streams. The effects of the process variables initial feed concentration, air flow rate, foami...
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Yeasts are widely used in production of recombinant proteins of medical or industrial interest. For each individual product, the most suitable expression system has to be identified and optimized, both on the genetic and fermentative level, by taking into account the properties of the product, the organism and the expression cassette. There is a wide range of important yeast expression hosts including the species Saccharomyces cerevisiae, Pichia pastoris, Hansenula polymorpha, Kluyveromyces lactis, Schizosa...
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A rapid and simple method of staining for the crystal protein (δ-endotoxin or parasporal body) ofBacillus thuringiensis has been developed. Changes in colonial morphology were observed when cells lost their ability to form crystal protein or both crystal protein and spore.
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A simple microbiological technique was used to differentially enumerate growth of Streptococcus thermophilus and Lactobacillus bulgaricus in a mixed culture. The growth of the microorganisms in the mixed culture was satisfactorily simulated with a set of modified logistic equations. This simple model was valid for various initial biomass concentrations and their ratios. It did not need substrate or product data for simulation of biomass growth, which may simplify the calculations in fermenter design. It was...
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Citation Formats
P. Çalık and T. H. Ozdamar, “Human growth hormone-specific aptamer identification using improved oligonucleotide ligand evolution method,” PROTEIN EXPRESSION AND PURIFICATION, pp. 21–28, 2010, Accessed: 00, 2020. [Online]. Available: