Browsing by Author "Yang, YS"

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1.2V sub-nanoampere A/D converter
(2005-04-14)
Rachmuth, G
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Yang, YS
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Poon, CS
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生物科技學系
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Department of Biological Science and Technology
CMOS-based integrated biochemical sensors generate photo currents at sub-nanoampere (nA) levels, which present a challenge for digital data acquisition. Proposed is a MOS current-mode analogue-to-digital converter with sub-nA sensitivity. Its inherent low-voltage low-power and small-size capabilities are ideal for portable chemi- or biosensor applications.
A Bayesian approach to obtain a lower bound for the C-pm capability index
(2005-10-01)
Lin, GH
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Pearn, WL
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Yang, YS
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工業工程與管理學系
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Department of Industrial Engineering and Management
The Taguchi capability index C-pm, which incorporates the departure of the process mean from the target value, has been proposed to the manufacturing industry for measuring manufacturing capability. A Bayesian procedure has been considered for testing process performance assuming mu = T, which was generalized without assuming mu = T. Statistical properties of the natural estimator of the index C-pm for normal processes have been investigated extensively. However, the investigation was restricted to processes with symmetric tolerances. Recently, a generalized C-pm, referred to as C-pm", was proposed to cover processes with asymmetric tolerances. Under the normality assumption, the statistical properties of the estimated C-pm" including the exact sampling distribution, the rth moment, expected value, variance, and the mean-squared error were obtained. In this paper, we use a Bayesian approach to obtain the interval estimation for the generalized Taguchi capability index C-pm" Consequently, the manufacturing capability testing can be performed for quality assurance. Copyright (c) 2005 John Wiley & Sons, Ltd.
A nano-switch regulates the activity of redox-responsive phenol sulfotransferase
(2004-05-14)
Yang, YS
;
Su, TM
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交大名義發表
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National Chiao Tung University
A novel cold-adapted imidase from fish Oreochromis niloticus that catalyzes hydrolysis of maleimide
(2003-12-12)
Huang, CY
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Yang, YS
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生醫工程研究所
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Institute of Biomedical Engineering
In this paper we report the first comparative study of cold-adapted imidase (EC 3.5.2.2) from the fish (Oreochromis niloticus) liver and its thermophilic counterparts taken from pig liver and Escherichia coli (overexpressed recombinant hydantoinase from Agrobacterium radiobacter NRRL B1). Approximately 6000-fold purification and a 40% yield of fish imidase activity were obtained through ammonium sulfate precipitation, octyl, chelating, DEAE, and hydroxyapatite chromatography. This cold-adapted imidase was characterized by a specific activity 10- to a 100-fold higher than those of its thermophilic counterparts below room temperature (25 degreesC or lower) conditions but less stable at elevated temperatures (40 degreesC or higher). A less organized helical structure (compared to those of pig liver and bacterial imidases) was observed by circular dichroism. Furthermore, maleimide was first identified as a novel substrate of all imidases examined, and confirmed by HPLC and NMR analysis. These results constituted a first study to discover a novel cold-adapted imidase with surprising high activity. These findings might be also helpful for industrial application of imidase. (C) 2003 Elsevier Inc. All rights reserved.
A simple and low-cost method to fabricate TFTs with poly-Si nanowire channel
(2005-09-01)
Lin, HC
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Lee, MH
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Su, CJ
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Huang, TY
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Lee, CC
A very simple and low-cost scheme is proposed for fabricating thin-film transistors with poly-Si nanowire (NW) channels. In this scheme, the poly-Si NW channel is formed by cleverly employing the poly-Si sidewall spacer technique. In addition, the poly-Si NW channel is genuinely exposed to the environment after the poly-Si sidewall spacer formation in the new scheme. This unique feature, together with its simplicity and low-cost, makes this approach very suitable for applications and manufacturing of bio-logic sensing devices. Good device performance is demonstrated in this letter.
A single mutation converts the nucleotide specificity of phenol sulfotransferase from PAP to AMP
(2002-10-29)
Hsiao, YS
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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
Sulfotransferases (STs) catalyze all the known biological sulfonations, in which a sulfuryl group from a common sulfonate donor such as 3'-phosphoadenosine 5-phosphosulfate (PAPS) is transferred to a nucleophilic acceptor. In addition to PAPS, phenol sulfotransferase (PST), a member of the ST family, utilizes other nucleotides as substrates with much less catalytic efficiency [Lin, E. S., and Yang, Y. S. (2000) Biochem. Biophys. Res. Commun. 271, 818-822]. Six amino acid residues of PST have been chosen for mutagenesis studies on the basis of a model of PST and its sequence alignment with those of available cytosolic and membrane-anchored STs. Systematic analyses of the mutants reveal that Ser134 is important for the regulation of nucleotide specificity between 3'-phosphoadenosine 5'-phosphate (PAP) and adenosine 5'-monophosphate (AMP). Kinetic studies also indicate that Ser134 plays a key role in nucleotide binding (K-m) but not in catalysis (k(cat)). Consequently, the catalytic efficiency (k(cat)/K-m) of PST can be altered by 5 orders of magnitude with a mutation of Ser134. Moreover, the change in nucleotide specificity from PAP to AMP can be achieved by mutation of Ser134 to any of the following residues: Glu, Gln, Arg, and His. Roles of Lys44, Arg126, and Arg253, which interact directly with the 5'- and 3'-phosphate of PAP, were also investigated by mutagenesis and kinetic experiments. On the basis of these findings, we suggest that Ser134 is the key residue that enables PST to discriminate PAP from AMP.
Applications of microtube array on transtlective liquid crystal displays for backlight efficiency enhancement
(2004-12-01)
Yang, YS
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Huang, YP
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Shieh, HPD
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Tsai, MC
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Tsai, CY
A novel transflective liquid crystal display (LCD) with a microtube array structure to make the most effective use of backlight was demonstrated. By redefining the area ratio of transmissive and reflective regions, high light efficiency in both transmissive and reflective subpixels can be attained. Based on the principle of light collection, a simulation model was established to characterize the features and optimize the microtube array structure. Furthermore, a typical TFT-LCD process was utilized to fabricate the optimized structure. A prototype microtube array was fabricated, and the measured enhancement of backlight utilization efficiency can be as high as a factor of 1.81.
CMOS chip as luminescent sensor for biochemical reactions
(2003-06-01)
Lu, U
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Hu, BCP
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Shih, YC
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Yang, YS
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Wu, CY
We describe a novel biochemical sensing method and its potential new biosensing applications. A light-sensitive complementary metal oxide semiconductor (CMOS) chip prepared through a standard 0.5-mum CMOS process was developed for measuring biochemical reactions. A light producing enzymatic reaction catalyzed by horseradish peroxidase (HRP) was designed as a platform reaction to determine the concentration of hydrogen. peroxide (H2O2) by the CMOS chip with a standard semiconductor parameter analyzer (HP4145). The kinetics of enzymatic reaction were determined and compared with a standard and sophisticated fluorometer (Hitachi F-4500) in a biochemical laboratory. Similar results were obtained by both instruments. Using glucose oxidase as an example, we further demonstrated that the HRP platform can be used to determine other H2O2 producing reactions with the CMOS system. The result points to an important application of the CMOS chip in biological measurements and in diagnosis of various health factors.
Colorimetric determination of the purity of 3 '-phospho adenosine 5'-phosphosulfate and natural abundance of 3 '-phospho adenosine 5 '-phosphate at picomole quantities
(1998-11-01)
Lin, ES
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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 work presents novel colorimetric methods not only to measure 3'-phospho adenosine 5'-phosphate (PAP) and 3'-phospho adenosine 5'-phosphosulfate (PAPS) in the range of picomoles, but also to determine the purity of PAPS or PAP contaminants in PAPS in the range of nanomoles. These methods exploit the availability of overexpressed phenol sulfotransferase (PST) and the fact that sulfuryl group transfer requires the use of PAP or PAPS as a cofactor or cosubstrate, Experimental results indicate that absorption at 400 nm due to the production of 4-nitrophenol (pNP) is catalyzed by PST when the sulfuryl group transfers from 4-nitrophenylsulfate (pNPS) to PAP or to 2-napthol, In the absence of an acceptor substrate, PAPS is hydrolyzed to PAP by PST and is determined by sulfation with pNPS before and after this reaction. The change of absorption of pNP at 400 nm corresponds to the amount of PAP that is hydrolyzed from PAPS. Moreover, a standard curve is constructed using authentic PAP and PAP-free PST. Furthermore, this curve is used to determine the amount of PAP in extracts of pig liver, rat liver, and Escherichia coli. (C) 1998 Academic Press.
Crystallization and preliminary X-ray diffraction analysis of thermophilic imidase from pig liver
(2003-05-01)
Huang, CY
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Chiang, SK
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Yang, YS
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Sun, YJ
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生物科技學系
Imidase is an enzyme, also known as dihydropyrimidinase (EC 3.5.2.2), hydantoinase, dihydropyrimidine hydrase or dihydropyrimidine amidohydrolase, that catalyzes the reversible hydrolysis of 5,6-dihydrouracil to 3-ureidopropionate and many other imides. Substrate specificity, metal content and amino-acid sequence all differ significantly between bacterial and mammalian imide-hydrolyzing enzymes. In this study, a thermophilic imidase was isolated from pig liver and crystallized. Two kinds of imidase crystals were grown by the hanging-drop vapour-diffusion method using polyethylene glycol MME 5000 and 2-propanol as precipitants. One belongs to the triclinic P-1 space group, with unit-cell parameters a = 96.35, b = 96.87, c = 154.87 Angstrom, alpha = 82.10, beta = 72.54, gamma = 77.19degrees, and the other belongs to the orthorhombic C222(1) space group, with unit-cell parameters a = 113.92, b = 157.22, c = 156.21 Angstrom.
Cytosolic sulfotransferases and environmental estrogenic chemicals
(2005)
Suiko, M
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Sakakibara, Y
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Liu, MY
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Yang, YS
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Liu, MC
Over the past three decades, a substantial body of evidence has accumulated on the estrogenic activities of numerous environmental compounds. These "environmental estrogens," consisting of pesticides and a variety of industrial chemicals and their by-products, are becoming ubiquitous in the environment and are making their way into the food chain. An important issue is whether vertebrate animals are equipped with mechanisms for the inactivation and/or disposal of environmental estrogens. This review attempts to summarize the currently available data concerning the sulfation of environmental estrogenic compounds by the cytosolic sulfotransferases in vertebrate animals. (c) Pesticide Science Society of Japan.
Detection of serum uric acid using the optical polymeric enzyme biochip system
(2004-07-15)
Huang, SH
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Shih, YC
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Wu, CY
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Yuan, CJ
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Yang, YS
An optical polymeric biochip system based on the complementary metal oxide semiconductor (CMOS) photo array sensor and polymeric enzyme biochip for rapidly quantitating uric acid in a one-step procedure was developed. The CMOS sensor was designed with N+/P-well structure and manufactured using a standard 0.5 mum CMOS process. The polymeric enzyme biochip was immobilized with uricase-peroxidase and used to fill the reacting medium with the sample. This study encompasses the cloning of the Bacillus subtilis uricase gene and expression in Escherichia coli, as well as the purification of uricase and measurement of its activity. The cloned uricase gene included an open reading frame of 1491 nucleotides that encodes a protein of approximately 55 kDa. The expression of the putative MBP-fusion protein involved approximately 98 kDa of the protein. The CMOS sensor response was stronger at a higher temperature range of 20-40degreesC, with optimal pH at 8.5. The calibration curve of purified uric acid was linear in the concentration range from 2.5 to 12.5 mg/dL. The results obtained for serum uric acid correlated quite closely with those obtained using the Beckman Synchron method. (C) 2004 Elsevier B.V All rights reserved.
Discovery of a novel N-iminylamidase activity: substrate specificity, chemico selectivity and catalytic mechanism
(2005-03-01)
Huang, CY
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Yang, YS
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生醫工程研究所
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Institute of Biomedical Engineering
Enzymatic hydrolysis of the N-iminylamide was investigated in this study. An enzyme possessing N-iminylamidase activity from pig liver was purified to electrophoretic homogeneity. This enzyme was also active, however, with imides and appears to be identical to pig liver imidase. The identification was confirmed by copurification of enzyme activities and by specificities of typical substrates of mammalian imidase, such as phthalimide, dihydrouracil, and maleimide. The hydrolysis of 3-iminoisoindolinone was further analyzed by HPLC, C-13 NMR spectrometry, and LC-MS measurements to determine its chemicoselectivity. All data indicated that this enzyme chemicoselectively catalyzed the hydrolysis of the N-iminylamide to produce the compound bearing the diamine and carboxylate group. The pH profiles of this enzyme suggest that one of the protons of 3-iminoisoindolinone was important to promote the ring-opening process of this substrate. These results constituted a first study on the enzymatic hydrolysis of compounds bearing the N-iminylamide functional group. (c) 2004 Elsevier Inc. All rights reserved.
Distributional and inferential properties of the estimated precision C-p based on multiple samples
(2003-11-01)
Pearn, WL
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Yang, YS
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工業工程與管理學系
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Department of Industrial Engineering and Management
Process precision index C-p has been widely used in the manufacturing industry to provide numerical measures on process potential. Pearn et al. ( 1998) considered an unbiased estimator of C-p for one single sample. They showed that the unbiased estimator is the UMVUE. They also proposed an efficient test for C-p based on one single sample, and showed that the test is the UMP test. In this paper, we consider an unbiased estimator of C-p for multiple samples. We show that the unbiased estimator is the UMVUE of C-p, which is asymptotically efficient. We also consider an efficient test for C-p, and show that the test is the UMP test for multiple samples. The practitioners can use the proposed test on their in-plant applications to obtain reliable decisions.
Effect of pH, metal and temperature on the substrate specificity of a thermophilic imidase from pig liver
(2001-03-07)
Yang, YS
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Lin, SW
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Huang, CY
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交大名義發表
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National Chiao Tung University
Effects of 3 '-phosphoadenosine 5 '-phosphate on the activity and folding of phenol sulfotransferase
(1998-02-20)
Yang, YS
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Tsai, SW
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Lin, ES
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生物科技學系
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Department of Biological Science and Technology
Known spectroscopic and kinetic data are used to formulate pathways of the physiological and transfer reactions and the substrate inhibition of phenol sulfotransferase. Kinetic mechanisms indicate that release of PAP from enzyme complex is required for the physiological reaction but not for the transfer reaction. The pathways explain rate difference between the physiological and transfer reactions since the release of PAP is the rate-limiting step of the former reaction. Two enzyme species of phenol sulfotransferase which distinguish the physiological and transfer reaction were found to involve the binding of PAP. Differences between two forms of phenol sulfotransferase, alpha and beta, indicate that they assemble through different folding process. It is demonstrated that only alpha enzyme renatures in the presence of PAP and beta enzyme renatures only ir. the absence of PAP in vitro. In the over-expressed system, formation of alpha and beta phenol sulfotransferase is also dependent on the availability of PAP in Escherichia coli. It is concluded that folding of phenol sulfotransferase is assisted by PAP to form alpha enzyme. In the absence of PAT, beta form of phenol sulfotransferase is produced. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.
Fluorometric assay for alcohol sulfotransferase
(2005-04-01)
Chen, WT
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Liu, MC
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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
A sensitive fluorometric assay was developed for alcohol sulfotransferase (AST). This was the first continuous fluorometric assay reported for AST. It used 3 '-phosphoadenosine 5 '-phosphosulfate regenerated from 3-phosphoadenosine 5 '-phosphate by a recombinant phenol sulfotransferase (PST) using 4-methylumbelliferyl sulfate as the sulfuryl group donor. The recombinant PST did not use the alcohol substrate under the designed condition, and the sensitivity for AST activity was found to be comparable to that of radioactive assay as reported in the literature. The change of fluorescence intensity of 4-methylumbelliferone corresponded directly to the amount of active AST and was sensitive enough to measure nanogram or picomole amounts of the enzyme activity. This fluorometric assay was used to determine the activities of AST as purified form and in crude extracts of pig liver, rat liver, and Escherichia coli. Some properties of human dehydroepiandrosterone sulfotransferase were determined by this method and were found to be comparable to published data. Under similar assay conditions, the contaminated activities of arylsulfatase in crude extracts were also determined. This method not only is useful for the routine and detailed kinetic study of this important class of enzymes but also has the potential for the development of a high-throughput procedure using microplate reader. (c) 2004 Elsevier Inc. All rights reserved.
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.
Micro-tube array on transflective liquid crystal displays for enhancing the backlight utilization efficiency
(2004)
Yang, YS
;
Huang, YP
;
Shieh, HPD
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光電工程學系
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Department of Photonics
A novel transflective LCD with micro-tube array structure is demonstrated to make most backlight be utilized effectively. By redistributing the area ratio of transmissive and reflective regions, high light efficiency in both transmissive and reflective sub-pixels can be yielded. Based on the principle of light collecting, a simulation model was established to characterize the features and optimize micro-tube array structure. Furthermore, a typical TFT-LCD process was utilized to fabricate the optimized structure. A prototype of inicro-tube array was fabricated, and the measured enhancement of back-light utilization efficiency can be a factor of 1.81.