Biomedical subjects

Dae Ryook Yang

Publications and source records attributed to Dae Ryook Yang.

4 recordsLinked to original sources

PubMed2006

Gliding arc plasma processing of CO2 conversion.

Conversion of carbon dioxide (CO2) using gliding arc plasma was performed. The research was done to investigate the effect of variation of total gas flow rates and addition of auxiliary gases--N2, O2, air, water--to the CO2 conversion process. This system shows higher power efficiency than other nonthermal plasma methods. Experiment results indicate the conversion of CO2 reaches 18% at total gas flow rate of 0.8 L/min and produces CO and O2 as the main gaseous products. Among auxiliary gases, only N2 gives positive effect on CO2 conversion and the power efficiency at N2 concentration of 95% and total gas flow rate of 2 L/min increases about three times compared to pure CO2 process.

Air Pollutants↗

PubMed2006

Lys296 and Arg299 residues in the C-terminus of MD-ACO1 are essential for a 1-aminocyclopropane-1-carboxylate oxidase enzyme activity.

The 1-aminocyclopropane-1-carboxylate (ACC) oxidase catalyzes the last step in the biosynthesis of ethylene from ACC in higher plants. The complex structure of ACC oxidase/Fe(2+)/H(2)O derived from Petunia hybrida has recently been established by X-ray crystallography and it provides a vast structural information for ACC oxidase. Our mutagenesis study shows that both Lys296 and Arg299 residues in the C-terminal helix play important roles in enzyme activity. Both K296R and R299K mutant proteins retain only 30-15% of their enzyme activities with respect to that of the wild-type, implying that the positive charges of C-terminal residues are involved in enzymatic reaction. Furthermore, the sequence alignment of ACC oxidases from 24 different species indicates an existence of the exclusively conserved motif (Lys296-Glu301) especially in the C-terminus. The structure model based on our findings suggests that the positive-charged surface in the C-terminal helix of the ACC oxidase could be a major stabilizer in the spatial arrangement of reactants and that the positive-charge network between the active site and C-terminus is critical for ACC oxidase activity.

Amino Acid Oxidoreductases↗

PubMed2004

The active site and substrate-binding mode of 1-aminocyclopropane-1-carboxylate oxidase determined by site-directed mutagenesis and comparative modelling studies.

The active site and substrate-binding mode of MD-ACO1 (Malus domestica Borkh. 1-aminocyclopropane-1-carboxylate oxidase) have been determined using site-directed mutagenesis and comparative modelling methods. The MD-ACO1 protein folds into a compact jelly-roll motif comprised of eight a-helices, 12 b-strands and several long loops. The active site is well defined as a wide cleft near the C-terminus. The co-substrate ascorbate is located in cofactor Fe2+-binding pocket, the so-called '2-His-1-carboxylate facial triad'. In addition, our results reveal that Arg244 and Ser246 are involved in generating the reaction product during enzyme catalysis. The structure agrees well with the biochemical and site-directed mutagenesis results. The three-dimensional structure together with the steady-state kinetics of both the wild-type and mutant MD-ACO1 proteins reveal how the substrate specificity of MD-ACO1 is involved in the catalytic mechanism, providing insights into understanding the fruit ripening process at atomic resolution.

Amino Acid Oxidoreductases↗

PubMed2003

Cybernetic modeling of the cephalosporin C fermentation process by Cephalosporium acremonium.

A cybernetic mathematical model has been developed to describe the production of cephalosporin C. In developing the model, diauxic behavior of substrate consumption, morphological differentiation of cells, and catabolite repression of cephalosporin C production by the preferred substrate, glucose, were considered. The proposed model was tested on the experimental data from the literature and could adequately describe the morphological differentiation of cells, the sequential utilization of carbon sources and the production of cephalosporin C. It could be a useful tool to optimize the production of cephalosporin C by Cephalosporium acremonium in batch, fed-batch or continuous operations.

Acremonium↗