Browsing by Author "Su, TM"

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A nano-switch regulates the activity of redox-responsive phenol sulfotransferase
(2004-05-14)
Yang, YS
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Su, TM
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交大名義發表
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National Chiao Tung University
A self-calibrated speaker tracking system using both audio and video data
(2002)
Hu, J
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Su, TM
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Cheng, CC
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Liu, WH
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Wu, TI
In this paper, a self-calibrated speaker tracking system applied on both image tracking and sound source detection is proposed. The sound source estimated by microphone system is used to supply video tracking system. On the other hand, the direction of speaker detected by image tracking system is fed back to calibrate the phase distortion between microphones. Some experiments using actual devices are also done to test the performance of the proposed method. It is shown that significant improvement in source localization accuracy is possible when the camera and the microphone system are well calibrated.
Identification, purification, and characterization of a thermophilic imidase from pig liver
(2000-07-01)
Su, TM
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Yang, YS
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生物科技學系
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Department of Biological Science and Technology
This study investigates thermophilic imidase activity of the liver. We demonstrate that imidase catalyzes the hydrolysis of imides at a temperature substantially higher than that of its native environment. Then, a thermophilic imidase is purified to homogeneity from pig liver, and its thermoproperties are studied. About 2500-fold of purification and 15% yield of imidase activity are obtained after ammonium sulfate precipitation, octyl, DEAE, chelation, and gel filtration chromatography, While avoiding heat treatment for the protein purification, this study also indicates that only one enzyme is responsible for the imidase activity. This homogenous enzyme prefers to catalyze hydrolysis of imides at above 60 degrees C rather than at the body temperature of a pig. Although stable at below 50 degrees C, imidase quickly loses its activity at above 65 degrees C. Thus, the temperature effect on imidase activity is limited mainly by its thermostability, Substrate specificity of imidase is also temperature dependent. Our results demonstrate that the hydrolysis of physiological substrates is the most temperature dependent and that of hydantoins is the least temperature dependent. When increasing the reaction temperature from 25 to 60 degrees C, specific activities increase 50- and 60-fold for dihydrouracil and dihydrothymine, respectively. The temperature effect on the K-m and V-max of imidase is substrate dependent. (C) 2000 Academic Press.
Mechanism of posttranslational regulation of phenol sulfotransferase: Expression of two enzyme forms through redox modification and nucleotide binding
(2003-06-10)
Su, TM
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Yang, YS
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生物科技學系
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Department of Biological Science and Technology
Sulfotransferase catalyzes sulfuryl group transfer between a nucleotide and a variety of nucleophiles that may be sugar, protein, xenobiotics, and other small molecules. Nucleotides may serve as cosubstrate, cofactor, inhibitor, or regulator in an enzyme catalyzed sulfuryl group transfer reaction. We are trying to understand how nucleotide regulates the activity of phenol sulfotransferase (PST) through the expression of two enzyme forms. The homogeneous rat recombinant PST was obtained from Escherichia coli, and the nucleotide copurified was examined. The nucleotide was completely removed from inactive PST in high salt and oxidative condition. Total enzyme activity was recovered following incubation in reductive environment. Many nucleotides are known to tightly bind to PST but only one nucleotide, 3'-phosphoadenosine 5'-phosphate (PAP), was identified to combine with PST by ion-pair RP-HPLC, UV-visible spectra, P-31 NMR, and ESI-MS and MS-MS spectrometry. In addition to the presence or absence of PAP, oxidation following reduction of PST was required to completely interconvert the two forms of PST. According to the experimental results, a mechanism for the formation of the two enzyme forms was proposed.
Robust environmental change detection using PTZ camera via spatial-temporal probabilistic modeling
(2005)
Hu, JS
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Su, TM
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電控工程研究所
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Institute of Electrical and Control Engineering
This paper presents a novel approach to detect environmental change using a Pan-Tilt-Zoom (PTZ) camera. Conventional pixel-based comparison methods require precision PTZ mechanisms and a large memory for background scene storage. The proposed method represents each scene captured by the camera using a spatial-temporal statistical model with much less parameters. Although the detail of the environment covered by the camera is lost, this model is efficient and robust in detecting the changes in the environment. The effectiveness of the method is demonstrated by experiments in a complex environment and relationship between the environmental change and the feature space parameters are observed.