Publications by authors named "Keresztessy Z"

While chromatin immunoprecipitation has become a widely-used method in the field of transcription regulation studies, serious limitations connected to the complexity and relatively little standardization of the method serve as obstacles for its use in clinical research. In this paper we introduce a method for developing bacteriophage-based controls for the better standardization of the chromatin immunoprecipitation reactions. Random phage display libraries were selected with ChIP-grade antibodies for several rounds and individual monoclonal phages were isolated.

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Differentiation syndrome (DS) is a life-threatening complication arising during retinoid treatment of acute promyelocytic leukemia (APL). Administration of all-trans retinoic acid leads to significant changes in gene expression, among the most induced of which is transglutaminase 2, which is not normally expressed in neutrophil granulocytes. To evaluate the pathophysiological function of transglutaminase 2 in the context of immunological function and disease outcomes, such as excessive superoxide anion, cytokine, and chemokine production in differentiated NB4 cells, we used an NB4 transglutaminase knock-out cell line and a transglutaminase inhibitor, NC9, which inhibits both transamidase- and guanosine triphosphate-binding activities, to clarify the contribution of transglutaminase to the development of potentially lethal DS during all-trans retinoic acid treatment of APL.

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Aging contributes to cellular stress and neurodegeneration. Our understanding is limited regarding the tissue-restricted mechanisms providing protection in postmitotic cells throughout life. Here, we show that spinal cord motoneurons exhibit a high abundance of asymmetric dimethyl arginines (ADMAs) and the presence of this posttranslational modification provides protection against environmental stress.

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N-glycosylation profiling of glycoprotein biotherapeutics is an essential step in each phase of product development in the biopharmaceutical industry. For example, during clone selection, hundreds of clones should be analyzed quickly from limited amounts of samples. On the other hand, identification of disease related glycosylation alterations can serve as early indicators (glycobiomarkers) for various pathological conditions in the biomedical field.

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In this paper, we report on a novel oriented peptide-N-glycosidase F (PNGase F) immobilization approach onto methacrylate based monolithic support for rapid, reproducible and efficient release of the N-linked carbohydrate moieties from glycoproteins. The glutathione-S-transferase-fusion PNGase F (PNGase F-GST) was expressed in Escherichia coli using regular vector technology. The monolithic pore surface was functionalized with glutathione via a succinimidyl-6-(iodoacetyl-amino)-hexanoate linker and the specific affinity of GST toward glutathione was utilized for the oriented coupling.

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The multifunctional tissue transglutaminase 2 (TG2) has a four-domain structure with several Ca(2+)-regulated biochemical activities, including transglutamylation and GTP hydrolysis. The structure of the Ca(2+)-binding form of the human enzyme is not known, and its Ca(2+)-binding sites have not been fully characterized. By mutagenesis, we have targeted its active site Cys, three sites based on homology to Ca(2+)-binding residues of epidermal transglutaminase and factor XIIIa (S1-S3), and two regions with negative surface potentials (S4 and S5).

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Understanding substrate specificity and identification of natural targets of transglutaminase 2 (TG2), the ubiquitous multifunctional cross-linking enzyme, which forms isopeptide bonds between protein-linked glutamine and lysine residues, is crucial in the elucidation of its physiological role. As a novel means of specificity analysis, we adapted the phage display technique to select glutamine-donor substrates from a random heptapeptide library via binding to recombinant TG2 and elution with a synthetic amine-donor substrate. Twenty-six Gln-containing sequences from the second and third biopanning rounds were susceptible for TG2-mediated incorporation of 5-(biotinamido)penthylamine, and the peptides GQQQTPY, GLQQASV, and WQTPMNS were modified most efficiently.

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Growth and beta-galactosidase activity of the penicillin producer industrial Penicillium chrysogenum NCAIM 00237 strain were examined using different carbon sources. Good growth was observed using glucose, sucrose, glycerol and galactose, while growth on lactose was substantially slower. beta-Galactosidase activity was high on lactose and very low on all the other carbon sources tested.

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Transglutaminases (TGases) form cross-links between glutamine and lysine side-chains of polypeptides in a Ca2+-dependent reaction. The structural basis of the Ca2+-effect is poorly defined. 43Ca NMR, surface polarity analysis combined with multiple sequence alignment and the construction of a new homology model of human tissue transglutaminase (tTGase) were used to obtain structural information about Ca2+ binding properties of factor XIII-A2, tTGase and TGase 3 (each of human origin).

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Two clones with homology to the alpha-hydroxynitrile lyase (HNL) cDNA clone, MeHNL10, were isolatedfrom a lambdaEMBL3 cassava (Manihot esculenta Crantz) genomic library. Analysis of the sequences showed that both genomic clones contain HNL genes (MeHNL4, MeHNL24) which are interrupted by two introns. RT-PCR analysis of MeHNL4 shows that it is expressed at high levels in seedling roots and at lower levels in cotyledons and young leaves.

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The homology modelling technique was used to predict the tertiary structures of three members of the low-temperature-inducible barley vegetative shoot epidermal lipid-transfer protein (LTP) family, BLT4, on the basis of the X-ray crystallographically determined three-dimensional structure of a maize seedling LTP. Differences between the maize LTP and the BLT4 family include amino acid substitutions around the entrance and inside the predicted hydrophobic binding tunnels of these proteins. Because of the deletion of the loop region corresponding to Val60-Gly62 of the maize LTP from all three BLT4 LTPs, their internal hydrophobic tunnels are longer.

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