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31.
32.
Copper amine oxidase contains a covalently bound quinonoid cofactor, 2,4,5-trihydroxyphenylalanyl quinone (TPQ), which is synthesized by post-translational modification of a specific tyrosyl residue occurring in the highly conserved sequence, Asn-Tyr-(Asp/Glu)-Tyr. To elucidate the role(s) of the conserved sequence in the biogenesis of TPQ, each of the corresponding residues at positions 401-404 in the recombinant histamine oxidase from Arthrobacter globiformis has been replaced with other amino acids by site-directed mutagenesis. When Asn-401 was changed to Asp or Gln, the rate of TPQ formation by copper-dependent self-processing was 10(3)- to 10(4)-fold slower than in the wild-type enzyme. When Tyr-402 was replaced by Phe, TPQ was not formed at all, showing that Tyr-402 is essential as the precursor to TPQ. In contrast, Asp-403 could be replaced by Glu without changes in the rate of TPQ formation, whereas its replacement by Asn led to a marked decrease. Furthermore, when Tyr-404 was changed to Phe, TPQ was formed swiftly on incubation with copper ions, but the TPQ enzyme exhibited very low activity with altered substrate specificity. These results collectively indicate that a very rigorous structural motif is required for efficient formation of TPQ and for the catalytic activity in the active site of copper amine oxidases. 相似文献
33.
O Motohashi M Suzuki N Shida K Umezawa T Ohtoh Y Sakurai T Yoshimoto 《Canadian Metallurgical Quarterly》1995,136(1-2):88-91
Subarachnoid haemorrhage (SAH) often leads to subarachnoid fibrosis and resultant normal pressure hydrocephalus; however, how subarachnoid fibrosis occurs is unknown. We examined the changes within arachnoid granulations (AGs) and the subarachnoid space (SAS) chronologically at the parasagittal region obtained from patients with SAH at autopsy and made comparison with controls by immunostaining for cytokeratin, specific marker for leptomeningeal cells and by the elastica Masson-Goldner methods. Within a week some AGs were torn, and many inflammatory cells filled the AGs and SAS. Cytokeratin positive cells were scarce. During the next two weeks cytokeratin positive cells increased. After three weeks, AGs and SAS were filled by dense deposits of extracellular matrices surrounded by multiple layers of leptomeningeal cells. 相似文献
34.
A potential barrier model along the grain boundaries in ultrathin tin dioxide (SnO2) gas sensors is presented. It is assumed that the negatively charged oxygens are adsorbed only on the grain boundaries. The
potential barrier depth is expressed as functions of grain size, donor concentration and surface coverage of adsorbed oxygen
ions at the boundaries. A direct consequence is that the conduction electrons are effectively confined in a grain when the
film thickness becomes smaller than a critical value. This indicates a drastic increase in resistivity with decreasing film
thickness in air, and thus an occurrence of an extremely high gas sensitivity. 相似文献
35.
H Matsubara N Oya Y Suzuki S Kajiura K Suzumori Y Matsuo T Suzuki T Hashimoto 《Canadian Metallurgical Quarterly》1997,12(5):306-308
Both choledochal cyst and congenital biliary atresia (type I cyst) may share the same ultrasonographic pattern. We report 2 cases which were shown to have cystic structures on the upper abdomen by antenatal ultrasonography. The size of the choledochal cyst found at 24 weeks' gestation increased steadily as gestational age advanced. But the size of the cyst in congenital biliary atresia found at 29 weeks' gestation remained unchanged throughout the remaining pregnancy. Cyst enlargement, therefore, may suggest the possibility of a choledochal cyst. 相似文献
36.
Sexual dysfunction is a well-documented complication among male hemodialysis patients. To evaluate it in detail, we conducted a sexual function survey using the Sapporo Medical University Sexual Function Questionnaire. Two hundred five male patients receiving outpatient hemodialysis were entered into this study. Patients with diabetes mellitus and severe anemia (Hb value < 8.0 g/dl) were excluded. The control group consisted of 3,462 healthy male subjects. Of male hemodialysis patients, 33.7% showed deterioration of libido, while 44.4% showed deterioration of potency, both of them decreased greatly with age. Ejaculatory ability correlated with potency. We compared the frequency of sexual intercourse in male hemodialysis patients with that in normal males. Twelve point nine percent of hemodialysis patients (HP) ranging from 30 to 39 in age versus 3.5% of age-matched normal males had no sexual intercourse and 22.4% of HPs from 40 to 49 versus 3.0% of age-matched normal males, 52.2% of HPs from 50 to 59 versus 7.5% of age-matched normal males, and 89.3% of HPs from 60 to 69 versus 18.0% of age-matched normal males had no sexual intercourse. These results revealed that the sexual frequency in hemodialysis patients decreased more than that in normal males in all age groups and with age. 相似文献
37.
Assignment of most genes encoding major peroxisomal polypeptides to chromosomal band V of the asporogenic yeast Candida tropicalis 总被引:1,自引:0,他引:1
The peroxisomes of the asporogenic yeast Candida tropicalis contain about 20 major polypeptides (PXPs). We have isolated a number of genes encoding them; 11 POX genes encoded independent PXPs and three POY genes were likely to encode three other PXPs. To locate these genes on the chromosomes, chromosomes of C. tropicalis were separated by pulsed-field gel electrophoresis. Eight chromosomal bands were observed over the range of 1.0 Mbp (band 1) to 2.8 Mbp (band VIII); the genome size was estimated to be about 20 Mbp. Southern blot analysis showed that ten genes were on band V, three genes were on band IV, and the other gene was on band VI. Three genes gave hybridization signals of nearly equal intensity on two different chromosomal bands: POX6A and POX8B, on bands V and VII; and POX8A, on bands IV and VI. Ribosomal RNA genes also hybridized to two bands, VI and VII. Most genes assigned to only one band hybridized to two restriction fragments produced by either NotI or SfiI endonuclease. The results suggested that C. tropicalis was diploid and that restriction sites were conserved little between homologues. The three POX genes that were found on two chromosomal bands hybridized to not more than two restriction fragments, implying that the allelic genes were present on different chromosomal bands. 相似文献
38.
Toshimitsu Suzuki Osamu Yamada Yasuhiko Takahashi Yoshihisa Watanabe 《Fuel Processing Technology》1985,10(1):33-43
Hydroliquefaction of low-sulfur Australian coals (Wandoan and Yallourn) was studied using iron carbonyl complexes as catalyst. The addition of Fe(CO)5 (2.8 wt% Fe of coal) increased coal conversion from 48.6 to 85.2% for Wandoan coal, and from 36.7 to 69.7% for Yallourn coal in 1-methylnaphthalene at 425°C under an initial hydrogen pressure of 50 kg cm?2. When molecular sulfur was added to iron carbonyls (Fe(CO)5, Fe2(CO)9 and Fe3(CO)12), higher coal converions ( > 92%) and higher oil yields (>46%) were obtained, along with an increase in the amount of hydrogen transferred to coal from the gas phase (0.2 to 2.8%, d.a.f. coal basis). In the liquefaction studies using a hydrogen donor solvent, tetralin, Fe(CO)5S catalyst increased the amount of hydrogen absorbed from the gaseous phase and decreased the amount of naphthalene dehydrogenated from tetralin. The direct hydrogen transfer reaction from molecular hydrogen to coal fragment radicals seems to be a major reaction pathway. Organic sulfur compounds, dimethyldisulfide and benzothiophene, and inorganic FeS2 and NiS were found to be good sulfur sources to Fe(CO)5. From X-ray diffraction analyses of liquefaction residues, it is concluded that Fe(CO)5 was converted into pyrrhotite (Fe1?xS) when sulfur was present, but into Fe3O4 in the absence of sulfur. 相似文献
39.
Yurak Son Takuya Kamano Takashi Yasuno Takayuki Suzuki Hironobu Harada 《Electrical Engineering in Japan》2006,155(1):35-43
This paper describes the generation of adaptive gait patterns using new Central Pattern Generators (CPGs) including motor dynamic models for a quadruped robot under various environments. The CPGs act as the flexible oscillators of the joints and adjust joint angles to required values. The CPGs are interconnected with each other and sets of their coupling parameters are adjusted by a genetic algorithm so that the quadruped robot can realize stable and adequate gait patterns. Generation of gait patterns results in the formation of the CPG networks suitable for the formation of not only a straight walking pattern but also of rotating gait patterns. Experimental results demonstrate that the proposed CPG networks are effective for the automatic adjustment of the adaptive gait patterns for the tested quadruped robot under various environments. Furthermore, the target tracking control based on image processing is achieved by combining the general gait patterns. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 155(1): 35–43, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20225 相似文献
40.