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排序方式: 共有209条查询结果,搜索用时 15 毫秒
21.
Maria Teresa Massucci Francesco Giansanti Giovanna Di Nino Manola Turacchio Maria Federica Giardi Dario Botti Rodolfo Ippoliti Barbara De Giulio Rosa Siciliano Giovanna Donnarumma Piera Valenti Alessio Bocedi Fabio Polticelli Paolo Ascenzi Giovanni Antonini 《Biometals》2004,17(3):249-255
Bovine lactoferrin catalyzes the hydrolysis of synthetic substrates (i.e., Z-aminoacyl-7-amido-4-methylcoumarin). Values of Km and kcat for the bovine lactoferrin catalyzed hydrolysis of Z-Phe-Arg-7-amido-4-methylcoumarin are 50 microM and 0.03 s(-1), respectively, the optimum pH value is 7.5 at 25 degrees C. The bovine lactoferrin substrate specificity is similar to that of trypsin, while the hydrolysis rate is several orders of magnitude lower than that of trypsin. The bovine lactoferrin catalytic activity is irreversibly inhibited by the serine-protease inhibitors PMSF and Pefabloc. Moreover, both iron-saturation of the protein and LPS addition strongly inhibit the bovine lactoferrin activity. Interestingly, bovine lactoferrin undergoes partial auto-proteolytic cleavage at positions Arg415-Lys416 and Lys440-Lys441. pKa shift calculations indicate that several Ser residues of bovine lactoferrin display the high nucleophilicity required to potentially catalyze substrate cleavage. However, a definitive identification of the active site awaits further studies. 相似文献
22.
23.
Gregor Stiglic Petra Povalej Brzan Nino Fijacko Fei Wang Boris Delibasic Alexandros Kalousis Zoran Obradovic 《PloS one》2015,10(12)
Different studies have demonstrated the importance of comorbidities to better understand the origin and evolution of medical complications. This study focuses on improvement of the predictive model interpretability based on simple logical features representing comorbidities. We use group lasso based feature interaction discovery followed by a post-processing step, where simple logic terms are added. In the final step, we reduce the feature set by applying lasso logistic regression to obtain a compact set of non-zero coefficients that represent a more comprehensible predictive model. The effectiveness of the proposed approach was demonstrated on a pediatric hospital discharge dataset that was used to build a readmission risk estimation model. The evaluation of the proposed method demonstrates a reduction of the initial set of features in a regression model by 72%, with a slight improvement in the Area Under the ROC Curve metric from 0.763 (95% CI: 0.755–0.771) to 0.769 (95% CI: 0.761–0.777). Additionally, our results show improvement in comprehensibility of the final predictive model using simple comorbidity based terms for logistic regression. 相似文献
24.
Evelina Colacino Antonella Converso Antonio De Nino Antonella Leggio Angelo Liguori Loredana Maiuolo 《Nucleosides, nucleotides & nucleic acids》2013,32(4-5):581-583
Abstract The complete set of the 4′-aza analogues of 2′,3′-dideoxynucleosides was synthesized by cycloaddition of N-tetrahydropiranyl or N-trityl methylene nitrones on suitably protected vinyl nucleobases. The convertible nucleoside approach was used in the preparation of cytosine and 5-methyl cytosine analogues. 相似文献
25.
Mavericks are virus-like mobile genetic elements found in the genomes of eukaryotes. Although Mavericks encode capsid morphogenesis homologs, their viral particles have not been observed. Here, we provide new evidence supporting the viral nature of Mavericks and the potential existence of virions. To this end, we conducted a phylogenomic analysis of Mavericks in hundreds of vertebrate genomes, discovering 134 elements with an intact coding capacity in 17 host species. We reveal an extensive genomic fossil record in 143 species and date three groups of elements to the Late Cretaceous. Bayesian phylogenetic analysis using genomic fossil orthologs suggests that Mavericks have infected osteichthyans for ∼419 My. They have undergone frequent cross-species transmissions in cyprinid fish and all core genes are subject to strong purifying selection. We conclude that vertebrate Mavericks form an ancient lineage of aquatic dsDNA viruses which are probably still functional in some vertebrate lineages. 相似文献
26.
Fortuna?Ponte Gloria?MazzoneEmail authorView authors OrcID profile Nino?Russo Emilia?Sicilia 《Journal of molecular modeling》2018,24(7):183
Density functional theory and its time-dependent extension (DFT, TDDFT) were employed to establish the feasibility of using a series of 4,4-difluoro-4-bora-3a,4a-diaza-s-indacenes (BODIPYs) in photodynamic therapy. Their absorption electronic spectra, singlet–triplet energy gaps, and spin–orbit matrix elements were computed and are discussed here. The effects of bromine substitution on the photophysical properties of BODIPY were elucidated. The investigated compounds were found to possess different excited triplet states that lie below the energy of the bright excited singlet state (S1 or S2), depending on the positions occupied by the bromine atoms. The computed spin–orbit matrix elements for the radiationless intersystem crossing Sn?→ ?Tm and the relative singlet–triplet energy gaps allowed the prediction of plausible nonradiative decay pathways for the production of singlet excited molecular oxygen, the key cytotoxic agent in photodynamic therapy. 相似文献
27.
E Colacino A Converso A De Nino A Leggio A Liguori L Maiuolo A Napoli A Procopio C Siciliano G Sindona 《Nucleosides & nucleotides》1999,18(4-5):581-583
The complete set of the 4'-aza analogues of 2',3'-dideoxynucleosides was synthesized by cycloaddition of N-tetrahydropiranyl or N-trityl methylene nitrones on suitably protected vinyl nucleobases. The convertible nucleoside approach was used in the preparation of cytosine and 5-methyl cytosine analogues. 相似文献
28.
Vladimir Elisashvili Eva Kachlishvili Nino Tsiklauri Eka Metreveli Tamar Khardziani Spiros N. Agathos 《World journal of microbiology & biotechnology》2009,25(2):331-339
The production of lignocellulolytic enzymes by eleven basidiomycetes species isolated from two ecosystems of Georgia was investigated
for the first time under submerged (SF) and solid-state fermentation (SSF) of lignocellulosic by-products. Notable intergeneric
and intrageneric differences were revealed with regard to the extent of hydrolase and oxidase activity. Several fungi produced
laccase along with hydrolases in parallel with growth during the trophophase, showing that the synthesis of this enzyme is
not connected with secondary metabolism. The lignocellulosic substrate type had the greatest impact on enzyme secretion. Some
of the substrates significantly stimulated lignocellulolytic enzyme synthesis without supplementation of the culture medium
with specific inducers. Exceptionally high carboxymethyl cellulase (CMCase, 122 U ml−1) and xylanase (195 U ml−1) activities were revealed in SF of mandarin peelings by Pseudotremella gibbosa IBB 22 and of residue after ethanol production (REP) by Fomes fomentarius IBB 38, respectively. The SSF of REP by T. pubescens IBB 11 ensured the highest level of laccase activity (24,690 U l−1), whereas the SSF of wheat bran and SF of mandarin peels provided the highest manganese peroxidase activity (570–620 U l−1) of Trichaptum biforme IBB 117. Moreover, the variation of lignocellulosic growth substrate provides an opportunity to obtain enzyme preparations
containing different ratios of individual enzymes. 相似文献
29.
Salzano A Kochiashvili N Nergadze SG Khoriauli L Smirnova A Ruiz-Herrera A Mondello C Giulotto E 《DNA Repair》2009,8(1):19-28
Gene amplification, a key mechanism for oncogene activation and drug resistance in tumour cells, involves the generation and joining of DNA double-strand breaks. Amplified DNA can be carried either on intra-chromosomal arrays or on extra-chromosomal elements (double minutes). We previously showed that, in rodent cells deficient in DNA-PKcs, intra-chromosomal amplification is significantly enhanced. In the present work, we studied gene amplification in human HeLa cell lines in which the expression of the DNA-PKcs gene was constitutively inhibited by shRNAs. These cell lines showed an increased sensitivity to ionizing radiations, an enhanced frequency of chromosomal aberrations and an increased rate of occurrence of methotrexate resistant colonies compared to the control cell lines (6-18 times). The main mechanism of resistance to methotrexate was extra-chromosomal amplification of the dihydrofolate reductase gene. These results indicate that, in human cells, inhibition of DNA-PKcs gene expression favours gene amplification occurring via the production of double minutes. In addition, they show that cell lines constitutively expressing shRNAs are good model systems to study the role of specific functions in gene amplification. 相似文献
30.
Nino Künzli Michael Jerrett Raquel Garcia-Esteban Xavier Basaga?a Bernardo Beckermann Frank Gilliland Merce Medina John Peters Howard N. Hodis Wendy J. Mack 《PloS one》2010,5(2)