51
|
Nardini M, Bedford R, Desai M, Mareschal D. Fusion of disparity and texture cues to slant is not mandatory in children. J Vis 2010. [DOI: 10.1167/10.7.494] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
|
52
|
Nardini M, Jones P, Bedford R, Braddick O. Development of optimal integration for self-motion and landmark cues in human navigation. J Vis 2010. [DOI: 10.1167/8.6.832] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
|
53
|
Nardini M, Bedford R, Mareschal D. The role of a perceptual decision rule in development of variance reduction by cue integration. J Vis 2010. [DOI: 10.1167/9.8.49] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
|
54
|
Atkinson J, Braddick OJ, Nardini M, Anker S, Cowan FM, Edwards AD, Rutherford MA. Visual and visuo-cognitive development in children born very prematurely: 'dorsal vulnerability' extended. J Vis 2010. [DOI: 10.1167/6.6.381] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
|
55
|
Atkinson J, Braddick O, Anker S, Nardini M, Bellugi U, Rose FE, Searcy Y, Bavar N. Extending the 'dorsal stream vulnerability hypothesis': Spatial reorientation and motion and form coherence in children and adults with Williams syndrome. J Vis 2010. [DOI: 10.1167/3.9.287] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
|
56
|
Carta M, Aguglia E, Balestrieri M, Bocchetta A, Drago F, Faravelli C, Morosini P, Nardini M, Hardoy M. The Use of Drugs for Mood Disorders in Italy: Preliminary Results. Eur Psychiatry 2009. [DOI: 10.1016/s0924-9338(09)71018-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
Background:Some community surveys in Italy have shown that a proportion of subjects without lifetime psychiatric diagnosis (anxiety/depression) used antidepressants. The prescription of AD in bipolar depression appears to be another largely underestimated problem in the clinical practice and is difficult to recognise by means of traditional epidemiological methods (lay interview and structured diagnostic tools).Objectives:The purpose is to use defined and validated international semi-structured interview as diagnostic instrument administered by expert clinicians to evaluate appropriateness and amount of over and under prescription of psychotropic drugs in different Italian community areas. The focus is on general antidepressant use and use in subjects with bipolar disorder and in subsyndromal depression.Methods:Study design: Community survey. Study population: sample randomly drawn, after stratification by sex and age, from the adult population of Municipal records in 6 Italian Regions: about 4000 persons will be interviewed. Tools: Questionnaire on psychotropic drugs consumption, prescription, health services utilisation;diagnostic Structured Clinical Interview np version;Mood Disorders Questionnaire; Short Form Health Survey. Ethical aspects: a signed informed consent for each candidate. The study was approved by the ethical committee of theItalain National Health Institute.Expected results:The study aims to identify the frequency of over and under prescription of psychotropic drugs in different Italian regions and the determinants of prescription related to physicians, patients, comorbidity and symptoms and to establish the basis for a cohort prospective study to assess the future changes.
Collapse
|
57
|
Marsili‐Libelli S, Nardini M. Stability and sensitivity analysis of anaerobic digestion models. ACTA ACUST UNITED AC 2008. [DOI: 10.1080/09593338509384381] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
|
58
|
Atkinson J, Braddick O, Anker S, Nardini M, Birtles D, Rutherford MA, Mercuri E, Dyet LE, Edwards AD, Cowan FM. Cortical vision, MRI and developmental outcome in preterm infants. Arch Dis Child Fetal Neonatal Ed 2008; 93:F292-7. [PMID: 18334617 DOI: 10.1136/adc.2007.116988] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
OBJECTIVES To test two measures of visual cortical function in the first year of life as early markers of functionally significant brain damage in infants born preterm: orientation-reversal visual event-related potentials (OR-VERP) and a behavioural test of cortically controlled visual attention-fixation shifts under competition (FS). Also to examine how these measures relate to (1) perinatal brain insults identified by MRI, and (2) later neurodevelopmental status. PATIENTS AND METHODS After neonatal and term-age-equivalent MRI, 26 preterm infants (<32 weeks of gestational age, mean 28.1 weeks) were given the OR-VERP and FS tests before 12 months post-term age and a neurodevelopmental assessment (Griffiths Scales) at 2 years. MRI scans examined for parenchymal lesions, intraventricular haemorrhage, ventricular dilatation and diffuse excessive high signal intensity were classified into three categories of severity. Cortical visual test results were compared across these categories and examined as predictors of developmental status at 2 years. RESULTS 26 infants were studied. 13/25 infants showed significant OR-VERP responses. 12/26 showed normal FS performance. On both tests, the proportion of infants meeting these criteria decreased significantly with MRI severity. As predictors of Griffiths developmental quotient < or =80, the FS test had a sensitivity of 100%, a specificity of 61%, and positive and negative predictive values of 50% and 100%, respectively; corresponding values for OR-VERP were 86%, 65%, 50% and 92% . CONCLUSIONS Visual cortical tests can provide early indicators of the functional impact of perinatal brain damage in the preterm infant.
Collapse
|
59
|
Corti S, Locatelli F, Papadimitriou D, Fortunato F, Del Bo R, Donadoni C, Nizzardo M, Nardini M, Salani S, Ghezzi S, Strazzer S, Bresolin N, Comi G. G.P.11.06 Fas siRNA mediated interference reduces motor neuron death in amyotrophic lateral sclerosis mouse model. Neuromuscul Disord 2007. [DOI: 10.1016/j.nmd.2007.06.213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
60
|
Mancuso M, Nardini M, Micheli D, Rocchi A, Nesti C, Giglioli NJ, Petrozzi L, Rossi C, Ceravolo R, Bacci A, Choub A, Ricci G, Tognoni G, Manca ML, Siciliano G, Murri L. Lack of association between mtDNA haplogroups and Alzheimer’s disease in Tuscany. Neurol Sci 2007; 28:142-7. [PMID: 17603766 DOI: 10.1007/s10072-007-0807-z] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2006] [Accepted: 04/10/2007] [Indexed: 10/23/2022]
Abstract
Mitochondrial DNA (mtDNA) haplogroup-specific polymorphisms were previously related to several neurodegenerative diseases, including Alzheimer's disease (AD). However, the precise role of mtDNA haplogroups in the neurodegenerative cascade leading to AD is still unclear. In this work we have genotyped predefined European mtDNA haplogroups in 209 patients with AD and 191 matched controls. In order to minimise the risk of "genetic contamination", which could lead to false associations between gene markers and disease, we were careful to enrol in the study only patients and controls of clear Tuscan origin (with at least three generations of Tuscanborn relatives). The frequency of the haplogroups did not differ between the two groups, and no correlation with gender, ApoE genotype, age of onset or disease status was observed. Further studies will be required to define the contribution of mtDNA haplogroups, if any, to the pathogenesis of AD. A correct population selection, in order to minimise the risk of genetic contamination, is essential in these studies.
Collapse
|
61
|
Bolognesi M, Nardini M, Pesce A, Guertin M. Structure of a group III truncated hemoglobin from Camphylobacter jejuni. Acta Crystallogr A 2006. [DOI: 10.1107/s0108767306096796] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
|
62
|
Bolognesi M, Nardini M. Structure and recognition in the BARS/CtBP-dependent transcription regulation. Acta Crystallogr A 2005. [DOI: 10.1107/s0108767305099988] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
|
63
|
Nardini M, Pesce A, Dewilde S, Moens L, Bolognesi M. Structural studies on Cerebratulus lacteusmini-Hb K(E10)W and L(G12)A mutants. Acta Crystallogr A 2005. [DOI: 10.1107/s0108767305090975] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
|
64
|
Anker S, Atkinson J, Braddick O, Nardini M, Ehrlich D. Non-cycloplegic refractive screening can identify infants whose visual outcome at 4 years is improved by spectacle correction. Strabismus 2005; 12:227-45. [PMID: 15545141 DOI: 10.1080/09273970490517935] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The Second Cambridge Population Infant Vision Screening Programme using the VPR-1 videorefractor without cycloplegia was undertaken in order to identify those infants with refractive errors who were potentially amblyogenic or strabismogenic. Infants identified at eight months were entered into a control trial of treatment with partial spectacle correction and underwent a long-term follow-up that monitored a wide range of visual, visuoperceptual, visuocognitive, visuomotor, linguistic and social development. In the present paper, the authors report on the outcome measures of visual acuity and strabismus. Poor acuity was defined as a best-corrected acuity of 6/12 or worse on crowded letters or 6/9 or worse on single letters, at age 4 years. Acuity was measured in 79 infants who were significantly hyperopic and/or anisometropic at 11-12 months of age, 23 who showed hyperopia of +3D but less than +3.5D, 196 control subjects, 14 controls with refractive errors, and 126 others who showed an accommodative lag on screening but were not significantly hyperopic on first retinoscopy. There was a poorer acuity outcome in the untreated group of hyperopes compared to controls (p < 0.0001) and to the children who were compliant in spectacle wear (p < 0.001) or who were prescribed spectacles (p < 0.05). Children who were significantly hyperopic at eight months were also more likely to be strabismic by 5.5 years compared to the emmetropic control group (p < 0.001). However, the present study did not find a significant difference in the incidence of strabismus between corrected and uncorrected hyperopic infants. Children who were not refractively corrected for significant hyperopia were four times more likely to have poor acuity at 5.5 years than infants who wore their hyperopic correction, supporting the findings of the First Cambridge Population Infant Vision Screening Programme.
Collapse
|
65
|
Nardini M, Macone A, Matarese RM. Determination of aminoethylcysteine ketimine decarboxylated dimer in human plasma and cultured cells by high-performance liquid chromatography with electrochemical detection. J Chromatogr B Analyt Technol Biomed Life Sci 2003; 795:319-27. [PMID: 14522036 DOI: 10.1016/s1570-0232(03)00597-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Aminoethylcysteine ketimine decarboxylated dimer (AECK-DD) is a natural compound with antioxidant properties of a new family of sulfur-containing amino acids. It has been detected in human urine and plasma, in mammalian cerebellum and, more recently, in dietary vegetables. In the present study, a simple, highly sensitive method using a high-performance liquid chromatography system with electrochemical detection (ECD) has been developed. The method showed excellent precision and accuracy. It has been found to be about 100-fold more sensitive than gas chromatographic method and 2000-fold more sensitive in respect to the liquid chromatography method with UV detection. The method showed the required features of specificity and sensitivity to detect aminoethylcysteine ketimine decarboxylated dimer in human plasma and in cultured cells after in vitro supplementation.
Collapse
|
66
|
Nardini M, Cirillo E, Natella F, Scaccini C. Absorption of phenolic acids in humans after coffee consumption. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2002; 50:5735-5741. [PMID: 12236707 DOI: 10.1021/jf0257547] [Citation(s) in RCA: 216] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Despite extensive literature describing the biological effects of polyphenols, little is known about their absorption from diet, one major unresolved point consisting of the absorption of the bound forms of polyphenols. In this view, in the present work we studied the absorption in humans of phenolic acids from coffee, a common beverage particularly rich in bound phenolic acids, such as caffeic acid, ferulic acid, and p-coumaric acid. Coffee brew was analyzed for free and total (free + bound) phenolic acids. Chlorogenic acid (5'-caffeoylquinic acid), a bound form of caffeic acid, was present in coffee at high levels, while free phenolic acids were undetectable. After alkaline hydrolysis, which released bound phenolic acids, ferulic acid, p-coumaric acid, and high levels of caffeic acid were detected. Plasma samples were collected before and 1 and 2 h after coffee administration and analyzed for free and total phenolic acid content. Two different procedures were applied to release bound phenolic acids in plasma: beta-glucuronidase treatment and alkaline hydrolysis. Coffee administration resulted in increased total plasma caffeic acid concentration, with an absorption peak at 1 h. Caffeic acid was the only phenolic acid found in plasma samples after coffee administration, while chlorogenic acid was undetectable. Most of caffeic acid was present in plasma in bound form, mainly in the glucuronate/sulfate forms. Due to the absence of free caffeic acid in coffee, plasma caffeic acid is likely to be derived from hydrolysis of chlorogenic acid in the gastrointestinal tract.
Collapse
|
67
|
Pesce A, Nardini M, Dewilde S, Ascenzi P, Riggs AF, Yamauchi K, Geuens E, Moens L, Bolognesi M. Crystallization and preliminary X-ray analysis of neural haemoglobin from the nemertean worm Cerebratulus lacteus. ACTA CRYSTALLOGRAPHICA SECTION D: BIOLOGICAL CRYSTALLOGRAPHY 2001; 57:1897-9. [PMID: 11717510 DOI: 10.1107/s0907444901015815] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2001] [Accepted: 09/26/2001] [Indexed: 02/22/2023]
Abstract
The nemertean worm Cerebratulus lacteus neural tissue haemoglobin (109 amino acids, the shortest known haemoglobin) has been overexpressed in Escherichia coli, purified and crystallized. A highly redundant native data set has been collected at the Cu K(alpha) wavelength to 2.05 A resolution. The crystals belong to the orthorhombic P2(1)2(1)2(1) space group, with unit-cell parameters a = 42.5, b = 43.1, c = 60.2 A and one molecule per asymmetric unit. The anomalous difference Patterson map clearly reveals the position of the haem Fe atom, thus paving the way for MAD/SAD structure determination.
Collapse
|
68
|
Finkelstein EI, Nardini M, van der Vliet A. Inhibition of neutrophil apoptosis by acrolein: a mechanism of tobacco-related lung disease? Am J Physiol Lung Cell Mol Physiol 2001; 281:L732-9. [PMID: 11504702 DOI: 10.1152/ajplung.2001.281.3.l732] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Cigarette smoking is known to contribute to inflammatory diseases of the respiratory tract by promoting recruitment of inflammatory-immune cells such as neutrophils and perhaps by altering neutrophil functional properties. We investigated whether acrolein, a toxic unsaturated aldehyde found in cigarette smoke, could directly affect neutrophil function. Exposure of freshly isolated human neutrophils to acrolein markedly inhibited spontaneous neutrophil apoptosis as indicated by loss of membrane asymmetry and DNA fragmentation and induced increased neutrophil production of the chemokine interleukin-8 (IL-8). Acrolein (1--50 microM) was found to induce marked activation of extracellular signal-regulated kinase (ERK) and p38 mitogen-activated protein kinases (MAPKs), and inhibition of p38 MAPK activation by SB-203580 prevented acrolein-induced IL-8 release. However, inhibition of either ERK or p38 MAPK did not affect acrolein-dependent inhibition of apoptosis. Acrolein exposure prevented the activation of caspase-3, a crucial step in the execution of neutrophil apoptosis, presumably by direct inhibition of the enzyme. Our results indicate that acrolein may contribute to smoke-induced inflammatory processes in the lung by increasing neutrophil recruitment and reducing neutrophil clearance by apoptosis.
Collapse
|
69
|
Marazziti D, Ori M, Nardini M, Rossi A, Nardi I, Cassano GB. mRNA expression of serotonin receptors of type 2C and 5A in human resting lymphocytes. Neuropsychobiology 2001; 43:123-6. [PMID: 11287788 DOI: 10.1159/000054878] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We investigated the presence of mRNA for serotonin receptors of type 2C (5-HT(2C)) in resting lymphocytes by means of RT-PCR and Southern blotting analyses, given their possible role in the pathophysiology of anxiety and eating disorders. At the same time, we explored also the presence of the specific mRNA for 5-HT(5A) receptors, a novel subtype for which still no functional data exist. Healthy subjects and patients with obsessive-compulsive or bipolar disorders were included in the study. The results showed the presence of the specific mRNAs for both 5-HT(2C) and 5-HT(5A) receptors in resting lymphocytes of the three groups of subjects. An additional band was also observed after the amplification of the 5-HT(5A) cDNA in each sample. These findings, while revealing the presence of 5-HT(2C) and 5-HT(5A) receptor mRNAs in an easily available tissue, can be considered preliminary for future quantitative analyses in patients with different psychiatric conditions.
Collapse
|
70
|
Altamura M, Pepe M, Tafaro A, Munno I, Bertolino A, Labriola D, Vacca A, Jirillo E, Nardini M. A syndrome characterized by psychiatric disorders, recurrent mucosal infections and natural immunity deficits: clinical approach. Immunopharmacol Immunotoxicol 2001; 23:303-6. [PMID: 11417856 DOI: 10.1081/iph-100103868] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The authors summarize their own previous work on the identification of a subset of patients characterized by psychiatric disorders, recurrency of mucosal infections and impaired natural immunity. The diagnostic approach to these patients based on the close collaboration between infectivologists, immunologists and psychiatrists is described with the aim to find out combined treatments for the amelioration of clinical manifestations.
Collapse
|
71
|
Nardini M, Leonardi F, Scaccini C, Virgili F. Modulation of ceramide-induced NF-kappaB binding activity and apoptotic response by caffeic acid in U937 cells: comparison with other antioxidants. Free Radic Biol Med 2001; 30:722-33. [PMID: 11275472 DOI: 10.1016/s0891-5849(00)00515-3] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Ceramide acts as second messenger in the signal transduction triggered by a variety of stress stimuli and extracellular agents. Stress response through ceramide is involved in the development of many human diseases, such as atherosclerosis, inflammation, neurodegenerative disorders, and acquired immunodeficiency syndrome. Dietary polyphenols have been reported to exert a beneficial effect on the onset and development of most of these human chronic-degenerative pathologies. However, the mechanisms underlying this beneficial effect are mostly not understood at the present. To investigate the ability of polyphenols in modulating fundamental cellular functions, we studied the effect of caffeic acid, a widespread phenolic acid largely present in human diet, in the modulation of ceramide-induced signal transduction pathway leading to apoptosis in U937 cells, in comparison with other established antioxidants of nutritional interest (N-acetylcysteine, d-alpha-tocopherol acetate and ascorbic acid). Our results indicate that caffeic acid efficiently inhibits both ceramide-induced NF-kappaB binding activity and apoptosis at micromolar concentration. Other antioxidants tested are totally ineffective in inhibiting apoptosis, although affecting NF-kappaB activation. Caffeic acid was found to inhibit protein tyrosine kinase activity, suggesting that this mechanism can be on the basis of the inhibition of apoptosis. Our results suggest that dietary caffeic acid might modulate ceramide-induced signal transduction pathway and NF-kappaB activation through either antioxidant and nonantioxidant mechanisms.
Collapse
|
72
|
Atkinson J, Anker S, Bobier W, Braddick O, Durden K, Nardini M, Watson P. Normal emmetropization in infants with spectacle correction for hyperopia. Invest Ophthalmol Vis Sci 2000; 41:3726-31. [PMID: 11053269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023] Open
Abstract
PURPOSE The development of emmetropic refraction is known to be under visual control. Does partial spectacle correction of infants' refractive errors, which has been shown to have beneficial effects in reducing strabismus and amblyopia, impede emmetropization? The purpose of the present study was to perform the first longitudinal controlled trial to investigate this question in human subjects. METHODS Children identified as having significant hyperopia in a population screening program at age 8 to 9 months were assigned to treated (partial spectacle correction) or untreated groups. A control group of infants with no significant refractive errors at screening was also recruited. Measurements of retinoscopic refraction under cycloplegia were taken at 4- to 6-month intervals up to the age of 36 months, and changes in refraction of 148 subjects were analyzed longitudinally. RESULTS Refractive error decreased toward low hyperopic values between 9 and 36 months in both hyperopic groups. By 36 months, this reduction of hyperopia showed no overall difference between children who were treated with partial spectacle correction and those who were not. Despite the improvement, both hyperopic groups' mean refractive error at 36 months remained higher than that of the control group. When infants in all three groups were considered together, the rate of reduction of refractive error was, on average, a linear function of the initial level of hyperopia. CONCLUSIONS The benefits of spectacle correction for infants with hyperopia can be achieved without impairing the normal developmental regulation of refraction.
Collapse
|
73
|
Nardini M, Lang DA, Liebeton K, Jaeger KE, Dijkstra BW. Crystal structure of pseudomonas aeruginosa lipase in the open conformation. The prototype for family I.1 of bacterial lipases. J Biol Chem 2000; 275:31219-25. [PMID: 10893416 DOI: 10.1074/jbc.m003903200] [Citation(s) in RCA: 204] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The x-ray structure of the lipase from Pseudomonas aeruginosa PAO1 has been determined at 2.54 A resolution. It is the first structure of a member of homology family I.1 of bacterial lipases. The structure shows a variant of the alpha/beta hydrolase fold, with Ser(82), Asp(229), and His(251) as the catalytic triad residues. Compared with the "canonical" alpha/beta hydrolase fold, the first two beta-strands and one alpha-helix (alphaE) are not present. The absence of helix alphaE allows the formation of a stabilizing intramolecular disulfide bridge. The loop containing His(251) is stabilized by an octahedrally coordinated calcium ion. On top of the active site a lid subdomain is in an open conformation, making the catalytic cleft accessible from the solvent region. A triacylglycerol analogue is covalently bound to Ser(82) in the active site, demonstrating the position of the oxyanion hole and of the three pockets that accommodate the sn-1, sn-2, and sn-3 fatty acid chains. The inhibited enzyme can be thought to mimic the structure of the tetrahedral intermediate that occurs during the acylation step of the reaction. Analysis of the binding mode of the inhibitor suggests that the size of the acyl pocket and the size and interactions of the sn-2 binding pocket are the predominant determinants of the regio- and enantio-preference of the enzyme.
Collapse
|
74
|
Pesce A, Battistoni A, Stroppolo ME, Polizio F, Nardini M, Kroll JS, Langford PR, O'Neill P, Sette M, Desideri A, Bolognesi M. Functional and crystallographic characterization of Salmonella typhimurium Cu,Zn superoxide dismutase coded by the sodCI virulence gene. J Mol Biol 2000; 302:465-78. [PMID: 10970746 DOI: 10.1006/jmbi.2000.4074] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The functional and three-dimensional structural features of Cu,Zn superoxide dismutase coded by the Salmonella typhimurium sodCI gene, have been characterized. Measurements of the catalytic rate indicate that this enzyme is the most efficient superoxide dismutase analyzed so far, a feature that may be related to the exclusive association of the sodCI gene with the most pathogenic Salmonella serotypes. The enzyme active-site copper ion is highly accessible to external probes, as indicated by quenching of the water proton relaxation rate upon addition of iodide. The shape of the electron paramagnetic resonance spectrum is dependent on the frozen or liquid state of the enzyme solution, suggesting relative flexibility of the copper ion environment. The crystal structure (R-factor 22.6%, at 2.3 A resolution) indicates that the dimeric enzyme adopts the quaternary assembly typical of prokaryotic Cu,Zn superoxide dismutases. However, when compared to the structures of the homologous enzymes from Photobacterium leiognathi and Actinobacillus pleuropneumoniae, the subunit interface of Salmonella Cu,Zn superoxide dismutase shows substitution of 11 out of 19 interface residues. As a consequence, the network of structural water molecules that fill the dimer interface cavity is structured differently from the other dimeric bacterial enzymes. The crystallographic and functional characterization of this Salmonella Cu,Zn superoxide dismutase indicates that structural variability and catalytic efficiency are higher in prokaryotic than in the eukaryotic homologous enzymes.
Collapse
|
75
|
Liebeton K, Zonta A, Schimossek K, Nardini M, Lang D, Dijkstra BW, Reetz MT, Jaeger KE. Directed evolution of an enantioselective lipase. CHEMISTRY & BIOLOGY 2000; 7:709-18. [PMID: 10980451 DOI: 10.1016/s1074-5521(00)00015-6] [Citation(s) in RCA: 202] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
BACKGROUND The biocatalytic production of enantiopure compounds is of steadily increasing importance to the chemical and biotechnological industry. In most cases, however, it is impossible to identify an enzyme that possesses the desired enantioselectivity. Therefore, there is a strong need to create by molecular biological methods novel enzymes which display high enantioselectivity. RESULTS A bacterial lipase from Pseudomonas aeruginosa (PAL) was evolved to catalyze with high enantioselectivity the hydrolysis of the chiral model substrate 2-methyldecanoic acid p-nitrophenyl ester. Successive rounds of random mutagenesis by ep-PCR and saturation mutagenesis resulted in an increase in enantioselectivity from E=1.1 for the wild-type enzyme to E=25.8 for the best variant which carried five amino acid substitutions. The recently solved three-dimensional structure of PAL allowed us to analyze the structural consequences of these substitutions. CONCLUSIONS A highly enantioselective lipase was created by increasing the flexibility of distinct loops of the enzyme. Our results demonstrate that enantioselective enzymes can be created by directed evolution, thereby opening up a large area of novel applications in biotechnology.
Collapse
|