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排序方式: 共有59条查询结果,搜索用时 15 毫秒
21.
Domenico Fulgione Valeria Maselli Giuseppe Pavarese Daniela Rippa Rakesh K. Rastogi 《European Journal of Wildlife Research》2009,55(4):385-396
During the last years, the population of Italian hare decreased significantly in central and south Italy. This is imputable
to harvest, poaching, habitat fragmentation, and the probable competition with congeneric European hare introduced in the
last decades by man for hunt. The goal of our work is to define the ecological characteristics of the two aforementioned species
in order to understand how landscape facilitates or impedes movement. Spatially explicit models are used to identify a species
ecological niche and to build a landscape model of suitability. To validate ecological modeling of landscape, we performed
a population genetic analysis. Results suggest that the Italian hare shows an ecological requirement close to average of available
resources in the considered landscape. The genetic structure of this autochthonous species validates the habitat suitability
model and highlights the differences with European hare. This work analyzes for the first time the ecological relationship
between those two sympatric species. 相似文献
22.
Rippa V Amoresano A Esposito C Landini P Volkert M Duilio A 《Journal of bacteriology》2010,192(23):6136-6142
Upon exposure to alkylating agents, Escherichia coli increases expression of aidB along with three genes (ada, alkA, and alkB) that encode DNA repair proteins. While the biological roles of the Ada, AlkA, and AlkB proteins have been defined, despite many efforts, the molecular functions of AidB remain largely unknown. In this study, we focused on the biological role of the AidB protein, and we demonstrated that AidB shows preferential binding to a DNA region that includes the upstream element of its own promoter, PaidB. The physiological significance of this specific interaction was investigated by in vivo gene expression assays, demonstrating that AidB can repress its own synthesis during normal cell growth. We also showed that the domain architecture of AidB is related to the different functions of the protein: the N-terminal region, comprising the first 439 amino acids (AidB "I-III"), possesses FAD-dependent dehydrogenase activity, while its C-terminal domain, corresponding to residues 440 to 541 (AidB "IV"), displays DNA binding activity and can negatively regulate the expression of its own gene in vivo. Our results define a novel role in gene regulation for the AidB protein and underline its multifunctional nature. 相似文献
23.
Affinity labelling of the NADP+-binding site of glucose 6-phosphate dehydrogenase from Candida utilis.
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1. Periodate-oxidized NADP+ inhibits the catalytic activity of glucose 6-phosphate dehydrogenase from Candida utilis, competing with NADP+. 2. Incubation of the enzyme with the coenzyme analogue causes partial reversible inactivation of the enzyme as a result of affinity labelling of the coenzyme-binding site. 3. Some kinetic values of the reaction were calculated. 4. The inactivation can be made irreversible by treatment with NaBH4, which reduces a Schiff base formed between an aldehyde group on the coenzyme analogue and a lysine residue on the enzyme. 5. Complete inactivation can be correlated with the binding of only one inhibitor to each enzyme subunit. 6. The lysine residue involved in the binding of the inhibitor is present at the coenzyme-binding site. 相似文献
24.
M Rippa T Bellini M Signorini F Dallocchio 《Archives of biochemistry and biophysics》1979,196(2):619-623
The reaction of NADP+ with periodate yields a coenzyme analog that can be bound to the NADP+ binding site of 6-phosphogluconate dehydrogenase from Candida utilis. This coenzyme analog can be irreversibly bound to the enzyme by reduction with sodium borohydride. The binding of one molecule of inhibitor to only one of the two subunits of the enzyme causes the inactivation of this subunit but does not alter the catalytic activity of the other subunit. Thus the two subunits do not have apparent catalytic interactions. When the reaction between the enzyme and the coenzyme analog is carried out in the presence of the substrate, the covalent modification of only one subunit causes the inactivation of both subunits. In this case the two subunits show an extreme negative cooperativity. It is suggested that the binding of the substrate induces in the enzyme molecule a conformational change that is stabilized by the irreversible binding of the coenzyme analog. 相似文献
25.
Fluorescein 5'-isothiocyanate binds almost selectively at the active site of lamb liver NADP-dependent 6-phosphogluconate dehydrogenase causing the inactivation of the enzyme. The substrate and the coenzyme protect against the loss of catalytic activity. The enzyme derivative was digested with trypsin, the labelled peptide was isolated by h.p.l.c. and its amino acid analysis allowed to establish that the inactivator binds to lysine 166 at the active site of the protein. 相似文献
26.
27.
Khasdan V Sapojnik M Zaritsky A Horowitz AR Boussiba S Rippa M Manasherob R Ben-Dov E 《Archives of microbiology》2007,188(6):643-653
The genes cry1Ac and cry1Ca from Bacillus thuringiensis subsps. kurstaki HD-73 and aizawai 4J4, respectively, encoding δ-endotoxins against lepidopteran larvae were isolated, cloned and expressed in Escherichia coli, with and without cyt1Aa (encoding cytolytic protein) and p20 (accessory protein) from subsp. israelensis. Nine combinations of the genes under control of an early T7, P
A1
inducible promoter, produced the encoding proteins. Toxicities were examined against larvae of three major agricultural pests:
Pectinophora gossypiella, Helicoverpa armigera and Spodoptera littoralis. The clones expressing cyt1Aa, with or without p20, were not toxic. The clone expressing cry1Ac (pBt-1A) was the most toxic to P. gossypiella (LC50 of 0.27 × 108 cells g−1). Clone pBt-1CA expressing cry1Ca and cry1Ac displayed the highest toxicity (LC50 of 0.12 × 108 cells ml−1) against S. littoralis. Clone pBt-1CARCy expressing all four genes (cry1Ca, cry1Ac, p20, cyt1Aa) in tandem exhibited the highest toxicity to H. armigera (LC50 of 0.16 × 108 cells ml−1). Cyt1Aa failed to raise the toxicity of these Cry toxins against P. gossypiella and S. littoralis but significantly enhanced toxicity against H. armigera. Two additional clones expressing either cry1Ac or cry1Ca under tandem promoters, P
A1
and P
psbA
(constitutive), displayed significantly higher toxicities (7.5- to 140-fold) than their counterparts with P
A1
alone, reducing the LC50 values to below 107 cells ml−1.
Vadim Khasdan and Maria Sapojnik are contributed equally to this work. 相似文献
28.
29.
Periodate-oxidized NADP+ binds specifically and reversibly to the NADP+ binding site of 6-phosphogluconate dehydrogenase (EC 1.1.1.44) from Candida utilis. The inhibition can be stabilized by reduction with sodium borohydride. It has been shown that an aldehydic group of the inhibitor forms a Schiff base with a lysine residue of the enzyme. 相似文献
30.
Changes of the "representative" maximum spatial cardiac vector were followed daily from the 1st till the 3th postnatal day of life in a group of 70 guinea-pigs. This vector representing the spatial vectorcardiographic loop shifted gradually during the observation period from the right caudal quadrant to the left caudal quadrant attaining its new spatial orientation on the 7th day. This shift is accompanied by a transitory tilt in the cranial direction with a peak on the 7th day and a transitory decrease of the spatial magnitude with a peak on the 4th day. There was no significant difference between the spatial magnitude of the "representative" maximum vector on the 1st and the last (13th) day of observation. 相似文献