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1.
Computer modeling of substrate binding to lipases from Rhizomucor miehei, Humicola lanuginosa, and Candida rugosa. 总被引:3,自引:3,他引:0 下载免费PDF全文
M. Norin F. Haeffner A. Achour T. Norin K. Hult 《Protein science : a publication of the Protein Society》1994,3(9):1493-1503
The substrate-binding sites of the triacyl glyceride lipases from Rhizomucor miehei, Humicola lanuginosa, and Candida rugosa were studied by means of computer modeling methods. The space around the active site was mapped by different probes. These calculations suggested 2 separate regions within the binding site. One region showed high affinity for aliphatic groups, whereas the other region was hydrophilic. The aliphatic site should be a binding cavity for fatty acid chains. Water molecules are required for the hydrolysis of the acyl enzyme, but are probably not readily accessible in the hydrophobic interface, in which lipases are acting. Therefore, the hydrophilic site should be important for the hydrolytic activity of the enzyme. Lipases from R. miehei and H. lanuginosa are excellent catalysts for enantioselective resolutions of many secondary alcohols. We used molecular mechanics and dynamics calculations of enzyme-substrate transition-state complexes, which provided information about molecular interactions important for the enantioselectivities of these reactions. 相似文献
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Mayada Achour Marc Mousli Mahmoud Alhosin Abdulkhaleg Ibrahim Jean Peluso Christian D. Muller Valérie B. Schini-Kerth Ali Hamiche Sirano Dhe-Paganon Christian Bronner 《Biochemical and biophysical research communications》2013,430(1):208-212
Ubiquitin-like containing PHD and Ring finger 1 (UHRF1) contributes to silencing of tumor suppressor genes by recruiting DNA methyltransferase 1 (DNMT1) to their hemi-methylated promoters. Conversely, demethylation of these promoters has been ascribed to the natural anti-cancer drug, epigallocatechin-3-gallate (EGCG). The aim of the present study was to investigate whether the UHRF1/DNMT1 pair is an important target of EGCG action. Here, we show that EGCG down-regulates UHRF1 and DNMT1 expression in Jurkat cells, with subsequent up-regulation of p73 and p16INK4A genes. The down-regulation of UHRF1 is dependent upon the generation of reactive oxygen species by EGCG. Up-regulation of p16INK4A is strongly correlated with decreased promoter binding by UHRF1. UHRF1 over-expression counteracted EGCG-induced G1-arrested cells, apoptosis, and up-regulation of p16INK4A and p73. Mutants of the Set and Ring Associated (SRA) domain of UHRF1 were unable to down-regulate p16INK4A and p73, either in the presence or absence of EGCG. Our results show that down-regulation of UHRF1 is upstream to many cellular events, including G1 cell arrest, up-regulation of tumor suppressor genes and apoptosis. 相似文献
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Afaf Bouchoucha Achour Terbouche Mohamed Zaouani Fazia Derridj Safia Djebbar 《Journal of trace elements in medicine and biology》2013,27(3):191-202
The synthesis and characterization by elemental analysis, emission atomic spectroscopy, TG measurements, magnetic measurements, FTIR, 1H NMR, UV–visible spectra and conductivity of a series of iron (II) and nickel (II) complexes with two heterocyclic ligands (L1(SMX): sulfamethoxazole and L2(MIZ): metronidazole) used in pharmaceutical field and with a new ligand derived benzoxazole (L3(MPBO): 2-(5-methylpyridine-2-yl)benzoxazole), were reported. The formulae obtained for the complexes are: [M(L1)2 Cl2]·nH2O, [M(L2)2Cl2(H2O)2]·H2O and [M(L3)2(OH)2]·nH2O. Stability constants of these complexes have been determined by potentiometric methods in water–ethanol (90:10, v/v) mixture at a 0.2 mol L?1 ionic strength (NaCl) and at 25.0 ± 0.1 °C. Sirko program was used to determine the protonation constants as well as the binding constants of three species [ML2H2]2+, [ML2] and [ML]2+. The antimicrobial activity of the ligands and complexes was evaluated in vitro against different human bacteria and fungi using agar diffusion method.Iron sulfamethoxazole complex showed a remarkable inhibition of bacteria growth especially on Staphylococcus aureus and P. aeruginosa. The iron metronidazole complex is active against yeasts especially on Candida tropicalis strain. Nickel complexes presented different antibacterial and antifungal behavior's against bacteria and fungal.The acute toxicity study revealed that the iron complexes are not toxic at 2000 mg/kg dose orally administrated.LD50 for nickel complexes was determined using graphical method.No significant differences in the body weights between the control and the treated groups of both rat sexes in subacute toxicity study using for iron complexes. Hematological and clinical blood chemistry analysis revealed no toxicity effects of the iron complexes. Pathologically, neither gross abnormalities nor histopathological changes were observed for these complexes. 相似文献
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In the present study, we have tested the sera of sixty five diabetic patients treated with insulin, researching the action of some physiologic and therapeutic factors (sex, age, insulin dose and time of treatment), to production of anti-insulin antibodies. Our results have shown that an important percentage of diabetic patients treated by porcine insulin produce antibodies: 72% of studied patients, concerning chiefly all the women and patients under-fourty years old. However our results have not pointed out any relation between the administered insulin dose versus the anti-insulin antibodies production, in spite of the early production of these antibodies in a great part of the patients. 相似文献
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Anis Raddaoui Alexandra S. Sim?es Rekaya Baaboura Sofia Félix Wafa Achour Tarek Ben Othman Mohamed Béjaoui Raquel Sá-Le?o Assia Ben Hassen 《PloS one》2015,10(10)
BackgroundPneumococcal disease, a major cause of morbidity and mortality globally, has higher incidence among young children, the elderly and the immunocompromised of all ages. In Tunisia, pneumococcal conjugate vaccines (PCVs) are not included in the national immunization program. Also, few studies have described the epidemiology of S. pneumoniae in this country and, in particular, no molecular typing studies have been performed. The aim of this study was to evaluate serotype distribution, antimicrobial resistance and clonality of Streptococcus pneumoniae isolated from neutropenic patients in Tunisia.MethodsFifty-nine S. pneumoniae were isolated from infection (n = 31) and colonization (n = 28) sites of patients (children and adults) attending the National Centre of Bone Marrow Transplantation in Tunis between 2005–2011. All isolates were characterized by serotype, antimicrobial resistance pattern and multilocus sequence typing (MLST).ResultsThe majority (66.1%) of the isolates belonged to five serotypes all included in PCVs: 6B, 9V, 14, 19F and 23F. The potential coverage of the 10-valent and 13-valent PCV was of 71.2% and 76.3% respectively. Resistance rates were very high and 69.5% of the isolates were multidrug resistant: non-susceptibility rates to penicillin, amoxicillin and cefotaxime were 66.1%, 40.7% and 27.1%, respectively; resistance rates to erythromycin, clindamycin, tetracycline, chloramphenicol and trimethoprim-sulfamethoxazole, were 69.5%, 61.0%, 37.3%, 22.0% and 67.8%, respectively. The most frequent serotypes had STs characteristic of multidrug resistant international clones known to be highly successful and important causes of pneumococcal infection: Spain 23F-ST81, France 9V/14-ST156, Spain 6B-ST90, 19F-ST320, and Portugal 19F-ST177.ConclusionsThe majority of S. pneumoniae strains recovered from immunocompromised patients in Tunisia are representatives of multidrug resistant pandemic clones that express serotypes targeted by PCVs. To contain the burden of pneumococcal disease and improve treatment choices among Tunisian immunocompromised patients PCVs should be offered to all of them. 相似文献
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Fabrice Neiers Chaithanya Madhurantakam Stefan Fälker Clothilde Manzano Staffan Normark Adnane Achour 《Journal of molecular biology》2009,393(3):704-352
The respiratory tract pathogen Streptococcus pneumoniae is a primary cause of morbidity and mortality worldwide. Pili enhance initial adhesion as well as the capacity of pneumococci to cause pneumonia and bacteremia. Pilus-associated sortases (SrtB, SrtC, and SrtD) are involved in the biogenesis of pneumococcal pili, composed of repeating units of RrgB that create the stalk to which the RrgA adhesin and the preferential pilus tip subunit RrgC are covalently associated. Using single sortase-expressing strains, we demonstrate that both pilin-polymerizing sortases SrtB and SrtC can covalently link pili to the peptidoglycan cell wall, a property shared with the non-pilus-polymerizing enzyme SrtD and the housekeeping sortase SrtA. Comparative analysis of the crystal structures of S. pneumoniae SrtC and SrtB revealed structural differences explaining the incapacity of SrtC, but not of SrtB, to incorporate RrgC into the pilus. Accordingly, site-directed mutagenesis of Thr160 in SrtB to an arginine as in SrtC (Arg160) partially converted its substrate specificity into that of SrtC. Solving two crystal structures for SrtC suggests that an opening of a flexible lid and a concomitant cysteine rotation are important for catalysis and the activation of the catalytic cysteine of pilus-associated sortases. 相似文献
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Staphylococcal Cassette Chromosome mec (SCCmec) is a mobile genetic element that carries the gene mecA mediating the methicillin resistance in staphylococci. It is composed of mec and ccr gene complexes. Six SCCmec types have been defined so far. SCCmec typing of 13 methicillin-resistant Staphylococcus aureus (MRSA) out of 72 (18%) non redundant S. aureus strains recovered in 1998–2007 at the Bone Marrow Transplant Centre of Tunis was carried out. The isolates were identified
by conventional methods. Antibiotic susceptibility was determined by oxacillin and cefoxitin disks and oxacillin MIC by E-test.
Methicillin resistance was detected by mecA PCR. The SCCmec complex types were determined by PCR. The epidemiology of MRSA has been investigated by PFGE. Among 13 mecA positive strains, 12 were resistant to oxacillin (MIC = 3 to >256 μg/μl) and to cefoxitin and one strain was pre-resistant:
susceptible to oxacillin (MIC = 0.19 μg/μl) and to cefoxitin. Hospital-acquired MRSA (HA-MRSA) strains had essentially SCCmec type IV (nine strains) or III (two strains) or I (one strain). One strain shown to carry ccrAB1 and ccrAB2 genes in combination with class B mec. Seven of 13 MRSA strains isolated from 2000 to 2006 were classified with major similarity group A harbored SCCmec type IV. 相似文献
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Tim Schulte Jonas L?fling Cecilia Mikaelsson Alexey Kikhney Karina Hentrich Aurora Diamante Christine Ebel Staffan Normark Dmitri Svergun Birgitta Henriques-Normark Adnane Achour 《Open biology》2014,4(1)
Streptococcus pneumoniae is a major human pathogen, and a leading cause of disease and death worldwide. Pneumococcal invasive disease is triggered by initial asymptomatic colonization of the human upper respiratory tract. The pneumococcal serine-rich repeat protein (PsrP) is a lung-specific virulence factor whose functional binding region (BR) binds to keratin-10 (KRT10) and promotes pneumococcal biofilm formation through self-oligomerization. We present the crystal structure of the KRT10-binding domain of PsrP (BR187–385) determined to 2.0 Å resolution. BR187–385 adopts a novel variant of the DEv-IgG fold, typical for microbial surface components recognizing adhesive matrix molecules adhesins, despite very low sequence identity. An extended β-sheet on one side of the compressed, two-sided barrel presents a basic groove that possibly binds to the acidic helical rod domain of KRT10. Our study also demonstrates the importance of the other side of the barrel, formed by extensive well-ordered loops and stabilized by short β-strands, for interaction with KRT10. 相似文献
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Identification and quantification of blood–brain barrier transporters in isolated rat brain microvessels 下载免费PDF全文
Hajar Al Feteisi Zubida M. Al‐Majdoub Brahim Achour Narciso Couto Amin Rostami‐Hodjegan Jill Barber 《Journal of neurochemistry》2018,146(6):670-685