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Herman A. Schreuder Alexander Liesum Katja Kroll Britta Böhnisch Christian Buning Sven Ruf Thorsten Sadowski 《Biochemical and biophysical research communications》2014
The lysosomal serine carboxypeptidase cathepsin A is involved in the breakdown of peptide hormones like endothelin and bradykinin. Recent pharmacological studies with cathepsin A inhibitors in rodents showed a remarkable reduction in cardiac hypertrophy and atrial fibrillation, making cathepsin A a promising target for the treatment of heart failure. Here we describe the crystal structures of activated cathepsin A without inhibitor and with two compounds that mimic the tetrahedral intermediate and the reaction product, respectively. The structure of activated cathepsin A turned out to be very similar to the structure of the inactive precursor. The only difference was the removal of a 40 residue activation domain, partially due to proteolytic removal of the activation peptide, and partially by an order–disorder transition of the peptides flanking the removed activation peptide. The termini of the catalytic core are held together by the Cys253–Cys303 disulfide bond, just before and after the activation domain. One of the compounds we soaked in our crystals reacted covalently with the catalytic Ser150 and formed a tetrahedral intermediate. The other compound got cleaved by the enzyme and a fragment, resembling one of the natural reaction products, was found in the active site. These studies establish cathepsin A as a classical serine proteinase with a well-defined oxyanion hole. The carboxylate group of the cleavage product is bound by a hydrogen-bonding network involving one aspartate and two glutamate side chains. This network can only form if at least half of the carboxylate groups involved are protonated, which explains the acidic pH optimum of the enzyme. 相似文献
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Gabriel Castrillo Eduardo Sánchez-Bermejo Laura de Lorenzo Pedro Crevillén Ana Fraile-Escanciano Mohan TC Alfonso Mouriz Pablo Catarecha Juan Sobrino-Plata Sanna Olsson Yolanda Leo del Puerto Isabel Mateos Enrique Rojo Luis E. Hernández Jose A. Jarillo Manuel Pi?eiro Javier Paz-Ares Antonio Leyva 《The Plant cell》2013,25(8):2944-2957
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Methylmethacrylate (MMA) is the most commonly used embedding medium for sectioning undecalcified bone; however, a number of problems exist with its use in a research laboratory. MMA requires a long infiltration time and temperature control, and it reacts with many polymers. We used Kleer Set resin? as an alternative embedding medium for sectioning undecalcified bone specimens. Fluorochrome labeled bone specimens were sectioned transversely using a ground section technique and longitudinally on a sledge macrotome. The slides were viewed using both transmitted light and epifluorescence microscopy. High quality sections were obtained using Kleer Set resin? for both sectioning techniques. We have shown that this new embedding medium is simpler, safer, quicker to use and does not interfere with visualization of fluorochromes. 相似文献
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Data on allele frequencies at six red cell blood group systems and three blood protein polymorphic loci in five goat breeds are reported. Two blood proteins, albumin and carbonic anhy-drase, were not found to be polymorphic. The B blood group system of goats, like its homologue in cattle and sheep, is highly complex. At least 44 B phenogroups (haplotypes) have been distinguished in this study. Based on the variation in allele frequencies between breeds, genetic distances were calculated. The distances estimated by four different methods were in close agreement with data from the history and geographic origins of the breeds examined. 相似文献
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Fuhai Li Xiaobo Zhou Jinmin Zhu Jinwen Ma Xudong Huang Stephen TC Wong 《BMC biotechnology》2007,7(1):66
Background
High content screening (HCS)-based image analysis is becoming an important and widely used research tool. Capitalizing this technology, ample cellular information can be extracted from the high content cellular images. In this study, an automated, reliable and quantitative cellular image analysis system developed in house has been employed to quantify the toxic responses of human H4 neuroglioma cells exposed to metal oxide nanoparticles. This system has been proved to be an essential tool in our study. 相似文献20.
Ruud van den Bos Tjard de Cock Buning 《Ethology : formerly Zeitschrift fur Tierpsychologie》1994,98(1):14-37
The behaviour of a group of female domestic cats (n = 10) under laboratory conditions is described. Behavioural observations were made on a total of 20 days during a 3-month period; only frequencies were recorded. Analysis of the winner/loser matrix revealed a linear rank order. This rank order correlated with several variables. The higher the rank, the more offensive threats a cat emitted overall, and the more defensive threats it received overall; within a pair, the higher-ranking cat displayed more offensive threats, whereas the lower-ranking cat displayed more defensive threats. The higher a rank, the more bouts of social licking a cat emitted overall, and the more bouts of social sniffing and social rubbing it received overall; within a pair, the higher-ranking cat tended to show more social licking, whereas the lower-ranking cat showed more social sniffing. The higher the rank, the more time a cat tended to spend on the floor, and the less time it spent in a 16-compartment complex; the further animals were apart in rank, the smaller were the proximity scores between them. Finally, higher-ranking cats tended to gain weight, whereas lower-ranking cats tended to lose weight. These data suggest that the concept of dominance may be applied to this group of cats. It is discussed whether the observed rank order is specific for indoor conditions under which the cats were living. The role of social licking is also discussed. 相似文献