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1.
Summary A new type of multistage fluidised-bed reactor was constructed to avoid the fluidisation irregularities by slow stirring of the bed. Aminoacylase immobilized on a polyacrylamide type bead polymer was used as biocatalyst for resolution of racemic amino acids. The efficiency was considerably higher than that of a traditional packed-bed reactor. 相似文献
2.
3-Phosphoglycerate kinase (ATP:3-phospho-d-glycerate 1-phosphotransferase, EC 2.7.2.3) has been covalently immobilized on a polyacrylamide-type support containing carboxylic groups activated by water-soluble carbodiimide. The activity was 88 units g?1 xerogel. The activity versus pH profile showed a sharper maximum at pH 6.5 in the case of the immobilized enzyme. The immobilized enzyme had a broad apparent optimum temperature range between 40 and 50°C. The apparent Km values of the immobilized 3-phosphoglycerate kinase were lower for both 3-phosphoglycerate and ATP than those of the soluble enzyme. In the case of the immobilized enzyme stabilities were enhanced. 相似文献
3.
Pig muscle lactate dehydrogenase (L-lactate:NAD oxidoreductase, EC 1.1.1.27) was covalently immobilized on polyacrylamide beads containing carboxylic functional groups activated by water-soluble carbodiimide. The effects of immobilization on the catalytic properties and stability of the lactate dehydrogenase were studied. There was no shift in the pH optimum of the immobilized enzyme compared to that of the soluble one. The apparent optimum temperature of the soluble enzyme was 65 degrees C, while that of the immobilized enzyme was between 50 and 65 degrees C. The apparent Km values of the immobilized enzyme with pyruvate and NADH substrates were higher than those of the soluble enzyme. As a result of immobilization, enhanced stabilities were found against heat treatment, changes in pH, and urea denaturation. 相似文献
4.
B. Szajáni Z. Buzás K. Dallmann I. Gimesi J. Krisch M. Tóth 《Applied microbiology and biotechnology》1996,46(2):122-125
Saccharomyces cerevisiae cells were immobilized on preformed cellulose beads by adsorption. The fermentation capacity of the immobilized yeast cells
was found to be practically independent of the hydrogen ion concentration between pH 3.1 and 6.25. The fermentation capacity
was maximal at 30 °C. The immobilized yeast cells were used for continuous production of ethanol in a fluidized-bead reactor.
The average values characteristic for the process were an ethanol concentration of 41.9±0.1 g l-1, a fermentation efficiency of 82.9±2.1% and a volumetric productivity of 3.94±0.52 g l-1 h-1.
Received: 9 October 1995/Accepted: 22 April 1996 相似文献
5.
H. Jansson § P.-I. Wyöni B. Fernholm † M. Bredwad ‡ A. Mierzykowska ‡ H. Tegelström 《Journal of fish biology》1995,47(4):599-608
Hagfish species of the genera Myxine, Eptatretus and Paramyxine were analysed for genetic variation by allozyme electrophoresis and isoelectric focusing of general proteins. Large genetic differences were observed between samples of supposed conspecifics of Myxine circifrons from off the Californian coast, and also within one sample of Paramyxine sp. from Sagami Bay, Japan. The results are convincing evidence of the existence of additional sympatric species in these two areas. In general, the highest genetic identities were found between species within the subfamilies Myxininae and Eptatretinae. Within Eptatretinae, the Japanese species Eptatretus burgeri was genetically more similar to Japanese species of Paramyxine than to American species of Eptatretus . Thus, our data indicate that the generic status of Paramyxine should be reconsidered. 相似文献
6.
Barbara Thöni 《Journal of Ornithology》1997,138(3):315-324
Zusammenfassung Im Frühjahr 1995 (Febr.–Mai) wurden auf der Schwäbischen Alb 7 Kolkrabenpaare beobachtet. Ziel der Untersuchung war es den Aufwand der Altvögel für die Jungenaufzucht zu erfassen. Der Aufwand wurde über die Aktivität der Altvögel am Nest abgeschätzt und bezüglich der Jungenzahl und des Wetters ausgewertet. Paare, die mehrere Junge hatten, sparten beim Hudern Kosten ein, da sie ihre Jungen bis zu einem geringeren Alter hudern mußten und weniger stark von der Temperatur abhängig waren. Bei den Fütterungen verringerte sich die Fütterfrequenz pro Jungvogel mit zunehmender Jungenzahl, die absolute Anzahl an Fütterungen nahm jedoch zu. Der Aufwand für die Nesthygiene war unabhängig von der Jungenzahl. Selbst bei mehreren Jungen blieb Zeit für Komfortverhalten. Jungenaufzucht war also effektiver, wenn mehrere Jungen gleichzeitig aufgezogen wurden.
Parental expenditure for rearing nestlings by ravensCorvus corax
In spring 1995 (Feb.–May) I observed seven pairs of Raven in southern Germany on the Schwäbischen Alb. The aim was to record parental expenditure for rearing nestlings. Expenditure was assessed by recording the activities of the adults at their nest (mainly brooding and feeding the offspring) and was analysed with respect to the number of nestlings per brood and with respect to the weather. Pairs with more than one nestling saved effort by stopping brooding their offspring at a lower nestling age. Also brooding was less dependent on the ambient temperature for pairs with more than one nestling than for pairs with only one nestling. The feeding frequency per nestling has been lower, if there were more nestlings to feed. The total frequency of feeding increased with increasing number of nestlings per brood. The effort for the hygiene of the nest was independent upon the number of offspring per nest. Nevertheless, pairs with more than one nestling spent time for comfort behaviour. Thus, it was more effective to reare more than one nestling at a time.相似文献
7.
The calcium hypothesis of cystic fibrosis 总被引:1,自引:0,他引:1
Data have been presented which suggests that various CF cell types show evidence of alterations in calcium homeostasis. The significance of these observations and the exact nature of the putative calcium defect in CF remains to be elucidated. It must also be determined whether this possible defect is primary, or is secondary or tertiary to some more basic lesion. The data reviewed suggests that altered calcium homeostasis may play some focal role in the aetiology or the pathogenesis of CF. 相似文献
8.
N Macková P Fedorocko P Brezáni 《Physiological research / Academia Scientiarum Bohemoslovaca》1991,40(5):503-512
The culture medium administered to C57Bl/6 mice 18 h and 8 h before a single irradiation (9 Gy) had a radioprotective effect and clearly influenced postirradiation changes in haemopoiesis. Haemopoiesis recovery appeared to be faster in culture medium-pretreated animals than in those irradiated without such pretreatment. By 12-15 days after irradiation, the thymus cortex appeared to be repaired, on day 21 a multiple increase in extramedullary erythropoiesis, myelopoiesis and megakaryocytopoiesis in the red pulp was found and later, on day 28, the lymphopoiesis in the white pulp of spleen was restored. The rate of haemopoiesis proliferation of predominantly myeloid cells which reached a control level on day 28 following irradiation. Consequently, the regenerative processes in blood-forming organs were accompanied by considerable reticulocytosis and complete recovery of neutrophil and platelet counts in the peripheral blood as seen on day 21. Despite a slower rate complete recovery of the total leukocyte count was reached by day 180 after irradiation. 相似文献
9.
1. A cationic protease has been purified from the granule fraction of blood-donor leukocytes by a preparative method including precipitation by acetone and chromatography on Bio-Gel A 1.5 m, CM-Sephadex C-50 and Sephadex G-G-75. 2. The pH optimum against denatured bovine hemoglobin is 7.4. Gel chromatography indicated a molecular weight close to 23 000. 3. This neutral protease (EC 3.4.-.-) is able to split the synthetic esters Z-Ala-NPh and AcAla3OMe, its activity on the former substrate being 2.2 times greater than that of pancreatic elastase, on the latter the same. It differs crucially from pancreatic elastase in having small elastinolytic activity. 4. In cationic disk electrophoresis, neutral protease resolves into three protein bands with lower mobility than lysozyme: all bands exhibit esterolytic activity against 2-acetoxy-3-naphthoic acid o-toluidide, strongly suggesting that they represent isoenzymes. 5. The enzyme is completely inhibited by iPr2P-F, partially so by soybean trypsin inhibitor and Trasylol. Cysteine, EDTA and TosLysCH2Cl have no effect. 6. During chromatography on CM-Sephadex C-50 a more positively charged enzyme(s) was identified. This had hemoglobinolytic activity at pH 7.4 but only a small esterolytic effect on Z-Ala-NPh; it showed only traces of activity against AcAla3OMe. 相似文献
10.