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Lígia O. Martins

Bio: Lígia O. Martins is an academic researcher from Universidade Nova de Lisboa. The author has contributed to research in topics: Laccase & Peroxidase. The author has an hindex of 35, co-authored 90 publications receiving 4242 citations. Previous affiliations of Lígia O. Martins include Universidade Lusófona & University of Coimbra.


Papers
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Journal ArticleDOI
TL;DR: This model of CotA contains all the structural features of a laccase, including the reactive surface-exposed copper center (T1) and two buried copper centers (T2 and T3), and shows a half-life of inactivation at 80 °C of about 4 and 2 h, indicating that CotA is intrinsically highly thermostable.

502 citations

Journal ArticleDOI
TL;DR: Comparisons with the structure of other monomeric multicopper oxidases containing four copper atoms suggest that CotA may accept the largest substrates of any known laccase, and unlike other laccases, CotA appears to have a flexible lidlike region close to the substrate-binding site that may mediate substrate accessibility.

357 citations

Journal ArticleDOI
TL;DR: EPR and resonance Raman data indicate that, presumably, folding in the presence of copper is indispensable for the correct structure of the trinuclear copper-containing site.
Abstract: The copper content of recombinant CotA laccase from Bacillus subtilis produced by Escherichia coli cells is shown to be strongly dependent on the presence of copper and oxygen in the culture media. In copper-supplemented media, a switch from aerobic to microaerobic conditions leads to the synthesis of a recombinant holoenzyme, while the maintenance of aerobic conditions results in the synthesis of a copper-depleted population of proteins. Strikingly, cells grown under microaerobic conditions accumulate up to 80-fold more copper than aerobically grown cells. In vitro copper incorporation into apoenzymes was monitored by optical and electron paramagnetic resonance (EPR) spectroscopy. This analysis reveals that copper incorporation into CotA laccase is a sequential process, with the type 1 copper center being the first to be reconstituted, followed by the type 2 and the type 3 copper centers. The copper reconstitution of holoCotA derivatives depleted in vitro with EDTA results in the complete recovery of the native conformation as monitored by spectroscopic, kinetic and thermal stability analysis. However, the reconstitution of copper to apo forms produced in cultures under aerobic and copper-deficient conditions resulted in incomplete recovery of biochemical properties of the holoenzyme. EPR and resonance Raman data indicate that, presumably, folding in the presence of copper is indispensable for the correct structure of the trinuclear copper-containing site.

179 citations

Journal ArticleDOI
TL;DR: The accumulation of organic solutes under optimum growth conditions in 12 species of thermophilic and hyperthermophilic Archaea belonging to the Crenarchaeota and Eury Archaeota was examined, and prominent among them was a compound identified as di-glycerol-phosphate.
Abstract: We examined the accumulation of organic solutes under optimum growth conditions in 12 species of thermophilic and hyperthermophilic Archaea belonging to the Crenarchaeota and Euryarchaeota. Pyrobaculum aerophilum, Thermoproteus tenax, Thermoplasma acidophilum, and members of the order Sulfolobales accumulated trehalose. Pyrococcus furiosus accumulated di-myo-inositol-1,1(prm1)(3,3(prm1))-phosphate and (beta)-mannosylglycerate, Methanothermus fervidus accumulated cyclic-2,3-bisphosphoglycerate and (beta)-mannosylglycerate, while the only solute detected in Pyrodictium occultum was di-myo-inositol-1,1(prm1)(3,3(prm1))-phosphate. Methanopyrus kandleri accumulated large concentrations of cyclic-2,3-bisphosphoglycerate. On the other hand, Archaeoglobus fulgidus accumulated three phosphorylated solutes; prominent among them was a compound identified as di-glycerol-phosphate. This solute increased in concentration as the salinity of the medium and the growth temperature were raised, suggesting that this compound serves as a general stress solute. Di-myo-inositol-1,1(prm1)(3,3(prm1))-phosphate accumulated at supraoptimal temperature only. The relationship between the accumulation of unusual solutes and high temperatures is also discussed.

164 citations

Journal ArticleDOI
TL;DR: X-ray structural comparison of M502L and M502F mutants with the wild-type CotA shows that the geometry of the T1 copper site is maintained as well as the overall fold of the proteins, indicating a key role in the regulation of CotA laccase activity.
Abstract: Site-directed mutagenesis has been used to replace Met502 in CotA laccase by the residues leucine and phenylalanine. X-ray structural comparison of M502L and M502F mutants with the wild-type CotA shows that the geometry of the T1 copper site is maintained as well as the overall fold of the proteins. The replacement of the weak so-called axial ligand of the T1 site leads to an increase in the redox potential by approximately 100 mV relative to that of the wild-type enzyme (E 0=455 mV). However the M502L mutant exhibits a twofold to fourfold decrease in the k cat values for the all substrates tested and the catalytic activity in M502F is even more severely compromised; 10% activity and 0.15–0.05% for the non-phenolic substrates and for the phenolic substrates tested when compared with the wild-type enzyme. T1 copper depletion is a key event in the inactivation and thus it is a determinant of the thermodynamic stability of wild-type and mutant proteins. Whilst the unfolding of the tertiary structure in the wild-type enzyme is a two-state process displaying a midpoint at a guanidinium hydrochloride concentration of 4.6 M and a free-energy exchange in water of 10 kcal/mol, the unfolding for both mutant enzymes is clearly not a two-state process. At 1.9 M guanidinium hydrochloride, half of the molecules are in an intermediate conformation, only slightly less stable than the native state (approximately 1.4 kcal/mol). The T1 copper centre clearly plays a key role, from the structural, catalytic and stability viewpoints, in the regulation of CotA laccase activity.

163 citations


Cited by
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28 Jul 2005
TL;DR: PfPMP1)与感染红细胞、树突状组胞以及胎盘的单个或多个受体作用,在黏附及免疫逃避中起关键的作�ly.
Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1(PfPMP1)与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用,在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员,通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

18,940 citations

01 Aug 2000
TL;DR: Assessment of medical technology in the context of commercialization with Bioentrepreneur course, which addresses many issues unique to biomedical products.
Abstract: BIOE 402. Medical Technology Assessment. 2 or 3 hours. Bioentrepreneur course. Assessment of medical technology in the context of commercialization. Objectives, competition, market share, funding, pricing, manufacturing, growth, and intellectual property; many issues unique to biomedical products. Course Information: 2 undergraduate hours. 3 graduate hours. Prerequisite(s): Junior standing or above and consent of the instructor.

4,833 citations

Journal ArticleDOI
TL;DR: The fact that laccases only require molecular oxygen for catalysis makes them suitable for biotechnological applications for the transformation or immobilization of xenobiotic compounds.
Abstract: Laccases of fungi attract considerable attention due to their possible involvement in the transformation of a wide variety of phenolic compounds including the polymeric lignin and humic substances. So far, more than a 100 enzymes have been purified from fungal cultures and characterized in terms of their biochemical and catalytic properties. Most ligninolytic fungal species produce constitutively at least one laccase isoenzyme and laccases are also dominant among ligninolytic enzymes in the soil environment. The fact that they only require molecular oxygen for catalysis makes them suitable for biotechnological applications for the transformation or immobilization of xenobiotic compounds.

1,925 citations

Journal ArticleDOI
TL;DR: Different treatment methods to treat the textile wastewater have been presented along with cost per unit volume of treated water, and the possible remedial measures to treat different types of effluent generated from each textile operation are recommended.

1,335 citations

Journal ArticleDOI
Wei Wang1
TL;DR: The basic behavior of proteins, their instabilities, and stabilization in aqueous state in relation to the development of liquid protein pharmaceuticals is discussed.

1,288 citations