• Biotechnology and Bioprocess Engineering:BBE
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• v.11 no.4
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• pp.344-350
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• 2006

Thermoplasma acidophilum is a thermoacidophilic archaeon that grows optimally at $59^{\circ}C$ and pH 2. Along with another thermoacidophilic archaeon, Sulfolobus solfataricus, it is known to metabolize glucose by the non-phosphorylated Entner-Doudoroff (nED) pathway. In the course of these studies, the specific activities of glyceraldehyde dehydrogenase and glycerate kinase, two enzymes that are involved in the downstream part of the nED pathway, were found to be much higher in T. acidophilum than in S. solfataricus. To characterize glycerate kinase, the enzyme was purified to homogeneity from T. acidophilum cell extracts. The N-terminal sequence of the purified enzyme was in exact agreement with that of Ta0453m in the genome database, with the removal of the initiator methionine. Furthermore, the enzyme was a monomer with a molecular weight of 49kDa and followed Michaelis-Menten kinetics with $K_m$ values of 0.56 and 0.32mM for DL-glycerate and ATP, respectively. The enzyme also exhibited excellent thermal stability at $70^{\circ}C$. Of the seven sugars and four phosphate donors tested, only DL-glycerate and ATP were utilized by glycerate kinase as substrates. In addition, a coupled enzyme assay indicated that 2-phosphoglycerate was produced as a product. When divalent metal ions, such as $Mn^{2+},\;CO^{2+},\;Ni^{2+},\;Zn^{2+},\;Ca^{2+},\;and\;Sr^{2+}$, were substituted for $Mg^{2+}$ the enzyme activities were less than 10% of that obtained in the presence of $Mg^{2+}$. The amino acid sequence of T. acidophilum glycerate kinase showed no similarity with E. coli glycerate kinases, which belong to the first glycerate kinase family. This is the first report on the biochemical characterization of an enzyme which belongs to a member of the second glycerate kinase family.

• The Journal of the Acoustical Society of Korea
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• v.16 no.3E
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• pp.50-55
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• 1997

Based on the anthropometric data of Korea male adults, a head and torso simulator(HATS) is constructed to measure its head related transfer functions (HRTFs) which can be used for three dimensional (3-D) sound localization. The HRTFs binaural impulse responses, are measured in an anechoic chamber using a burst maximum length sequence (MLS) signal of 65,535 samples and 32,768 samples acquisition at the sampling rate of 75.47kHz. Also measured are the impulse responses of a driving loudspeaker and some headphones for sound reproduction to get the exact HRTF of the HATS-alone. Through a post-processing procedure, the impulse-version HRTFs at the sampling frequency of 44.1 kHz, which have filter lengths of 512 points, are finally obtained. As an application of the measured HRTFs, a 3-D sound processor for headphone reproduction has been developed. The signal intervals to be processed can be selected and each interval is manipulated to have its diretionality and distance information by using corresponding HRTF and energy control.

• Journal of the Korean Institute of Navigation
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• v.20 no.2
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• pp.51-58
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• 1996

For the smooth flow of traffic vehicles and its effective management, it is necessary to have an exact information on traffic condition, i.e., the volume of traffic, velocity, occupancy and classification of vehicles. In particular, for classification of vehicles, there has been only image processing method using camera, where the method can obtain much information but rather expensive. In this paper, an algorithm for the measurement of velocity and total length of vehicles has been proposed to develop a general traffic management system, which is necessary to discriminate the class of vehicles. In order to realize the proposed algorithm, we have developed an ultrasonic spatial filtering method, which has better performance than that of using the traditional vehicle detector. To have this system to be constructed, we have introduced three sets of ultrasonic devices where each has one transmitter and two receivers which are arranged to obtain the spatial difference of objects. The velocity of vehicles can be measured by analyzing the occurrence time of pulses and their time differences. The total length of vehicles can be given by multiplying velocity with time interval of pulses sequence. To confirm the effectiveness of this measuring system, the experiment by the spatial filtering method using the ultrasonic sensors has been carried out. As the results, it is found that the proposed method can be used as one of measurement tools in the general traffic management system.

• Korean Journal of Microbiology
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• v.40 no.2
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• pp.104-110
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• 2004

To determine evolution and genotype of new chromosomal AmpC $\beta$-lactamases among clinical isolates of Enterobacter species, we performed antibiotic susceptibility testing, pI determination, sequencing, and phy-logenetic analysis using developed expression/secretion vector. Six isolates have shown to produce AmpC $\beta$-lactamases. Six genes of AmpC $\beta$-lactamases that are responsible for the resistance to cephamycins (cefoxitin and cefotetan), amoxicillin, cephalothin, and amoxicillin-clavulanic acid were cloned and characterized in pMSG12119. Insert fragment containing the ampC genes was sequenced and found to have an open reading frame coding for 381-amino-acid $\beta$-lactamase. The nucleotide sequence of four ampC genes ($bla_EcloK992004.l$, $bla_EcloK995120.1$, $bla_EcloK99230$, and $bla_EareK9911729$) shared considerable homology with that of chromosomal ampC gene ($bla_EcloMHN1$) of E. cloacae MHN1 (more than 99.6% identity). The sequences of two ampC genes ($bla_EcloK9973$ and $bla_EcloK9914325$) showed close similarity to the chromosomal ampC gene ($bla_EcloQ908R$) of E. clo-acae 908R (99.7% identity). The results from phylogenetic analysis suggested that six ampC genes could be originated from $bla_EcloMHN1$ / or $bla_EcloQ908R$ / MIC patterns and exact pI values of six transformants indicated that the developed expression/secretion vector (pMSG1219) was suitable for the characterization of foreign genes in E. coli strain.

• Development and Reproduction
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• v.20 no.1
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• pp.51-61
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• 2016

Neurokinin B (NKB) and neurokinin B related peptide (NKBRP) belong to tachykinin peptide family. They act as a neurotransmitter and/or neuromodulator. Mutation of NKB and/or its cognate receptor, NK3R resulted in hypogonadotropic hypogonadism in mammals, implying a strong involvement of NKB/NK3R system in controlling mammalian reproduction. Teleosts possess NKBRP as well as NKB, but their roles in fish reproduction need to be clarified. In this study, NKB and NKBRP coding gene (tac3) was cloned from Nile tilapia and sequenced. Based on the sequence, Nile tilapia NKB and NKBRP peptide were synthesized and their biological potencies were tested in vitro pituitary culture. The synthetic NKBRP showed direct inhibitory effect on the expression of GTH subunits at the pituitary level. This inhibitory effect was confirmed in vivo by means of intraperitoneal (ip) injection of synthetic NKB and NKBRP to mature female tilapia (20 pmol/g body weight [BW]). Both NKB and NKBRP had no effect on the plasma level of sex steroids, E2 and 11-KT. However, NKBRP caused declines of expression level of GnRH I, Kiss2 and tac3 mRNAs in the brain while NKB seemed to have no distinct effect. These results indicate some inhibitory roles of NKBRP in reproduction of mature female Nile tilapia, although their exact functions are not clear at the moment.