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Palangsuntikul R.,King Mongkuts University of Technology Thonburi | Somasundrum M.,Biochemical Engineering and Pilot Plant Research and Development Unit | Surareungchai W.,King Mongkuts University of Technology Thonburi
Electrochimica Acta | Year: 2010

Single-walled carbon nanotubes (SWNTs) were coated first with methylene blue (MB) by noncovalent adsorption and then by horseradish peroxidase (HRP) by cross-linking with glutaraldehyde. The MB-SWNT/HRP composites formed stable films on glassy carbon electrodes. MB was probably present with a coverage of a monolayer or less. The MB voltammetry was consistent with fast electron transfer to a surface-confined species. The presence of HRP did not significantly affect the MB electrochemistry. MB could mediate electron transfer from HRP in the presence of H 2O 2. Cyclic voltammograms of this process were used to determine the rate constants for the reactions of the native ferriperoxidase with H 2O 2 and of the oxyferryl Compound II with the reduced form of MB. For comparison purposes, the rate constant for the direct electrode reduction of the HRP oxyferryl π-cation radical Compound I was determined in MB-free SWNTs. The results indicate a considerably faster regeneration rate for native ferriperoxidase by the mediated reaction than by direct electrochemistry. Using the MB-SWNT/HRP composites, H 2O 2 could be calibrated by amperometry at -0.3 V vs. SCE. The optimized response (at pH 7.0) had a sensitivity of 661.0 μA mM -1 cm -2 and a limit of detection (3 × S/N) of 0.1 μM. © 2010 Elsevier Ltd.

Subpaiboonkit S.,Chiang Mai University | Thammarongtham C.,Biochemical Engineering and Pilot Plant Research and Development Unit | Cutler R.W.,Independent Research Scientist | Chaijaruwanich J.,Chiang Mai University
International Journal of Data Mining and Bioinformatics | Year: 2013

Non-coding RNAs (ncRNAs) have important biological functions in living cells dependent on their conserved secondary structures. Here, we focus on computational RNA secondary structure prediction by exploring primary sequences and complementary base pair interactions using the Conditional Random Fields (CRFs) model, which treats RNA prediction as a sequence labelling problem. Proposing suitable feature extraction from known RNA secondary structures, we developed a feature extraction based on natural RNA's loop and stem characteristics. Our CRFs models can predict the secondary structures of the test RNAs with optimal F-score prediction between 56.61 and 98.20% for different RNA families. Copyright © 2013 Inderscience Enterprises Ltd.

Mapaisansup T.,King Mongkuts University of Technology Thonburi | Yutthanasirikul R.,King Mongkuts University of Technology Thonburi | Hongsthong A.,Biochemical Engineering and Pilot Plant Research and Development Unit | Tanticharoen M.,Biochemical Engineering and Pilot Plant Research and Development Unit | Ruengjitchatchawalya M.,King Mongkuts University of Technology Thonburi
Journal of Applied Phycology | Year: 2013

Spirulina, a well-known cyanobacterium, is a potential alternative source for commercial γ-linolenic acid (C18:3Δ9,12,6, GLA) production. During the Spirulina desaturation process, three enzymes, which are encoded by desC, desA, and desD, respectively, introduce double bonds at the Δ9, Δ12, and Δ6 positions of stearic acid (C18:0), oleic acid (C18:1Δ9), and linoleic acid (C18:2Δ9,12). In the present study, transcriptional and translational expression of the desaturase genes during various growth phases of Spirulina platensis Z19/2 was examined. Moreover, the desaturase levels and fatty acids were analyzed in two subcellular locations, the plasma membrane and thylakoid membrane. The results obtained in this study indicated three important points: (1) the regulation level of each Spirulina desaturase gene is possibly subcellular location dependent; (2) GLA is important during cell division in the mid-log phase; and (3) vaccenic acid (C18:1Δ11), which is detected at high levels during the lag phase in the plasma membrane, might play a role in the mechanical strength of the cell membrane at low growth rates. © 2012 Springer Science+Business Media B.V.

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