Luís António Passarinha

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Catechol-O-methyltransferase (COMT, EC is an enzyme that catalyzes the methylation of catechol substrates, and while structural and functional studies of its membrane-bound isoform (MBCOMT) are still hampered by low recombinant production, Pichia pastoris has been described as an attractive host for the production of correctly folded and inserted(More)
The goal of this work was to develop and validate an analytical method for the detection and quantification of the biogenic amines serotonin (5-HT), dopamine (DA) and norepinephrine (NE), using microextraction in packed syringe (MEPS) and liquid chromatography coupled to electrochemical detection (HPLC-ED) in urine. The method was validated according to(More)
The aim of this work was to optimize the temperature, pH and stirring rate of the production of human soluble catechol-O-methyltransferase (hSCOMT) in a batch Escherichia coli culture process. A central composite design (CCD) was firstly employed to design the experimental assays used in the evaluation of these operational parameters on the hSCOMT activity(More)
Membrane proteins constitute 20-30% of all proteins encoded by the genome of various organisms. While large amounts of purified proteins are required for pharmaceutical and crystallization attempts, there is an unmet need for the development of novel heterologous membrane protein overexpression systems. Specifically, we tested the application of(More)
During the last few decades, it has become evident that the compatibility of the yeast biochemical environment with the ability to process and translate the RNA transcript, along with its capacity to modify a translated protein, are relevant requirements for selecting this host cell for protein expression in several pharmaceutical and clinical applications.(More)
The obtention of high yields of purified plasmid DNA is viewed as an essential issue to be considered towards efficient production of DNA vaccines and therapeutic plasmids. In this work, Escherichia coli DH5alpha bearing the pVAX1-LacZ plasmid was grown in a developed semi-defined medium at different temperatures and tryptone concentrations. Analysis of(More)
Chitosan, a natural biopolymer presents antifungal activity that seems to be dependent on the interaction of its cationic amino groups and yeast cell surface. In this work we used ion-exchange chromatography to assess the surface charge density of Candida species and subsequently to relate this with their sensitivity profile to chitosan. The ability of(More)
The main scope of this work is the evaluation and potential application of hydrophobic interaction chromatography in the isolation of recombinant human soluble catechol-O-methyltransferase (hSCOMT) from an Escherichia coli cell extract. Therefore, a comparative study on the interaction of recombinant hSCOMT with different hydrophobic adsorbents (butyl-,(More)
The enzyme catechol-O-methyltransferase (COMT) plays an important role in the metabolism of catechol estrogens and degradation of the catecholamine neurotransmitters, such as epinephrine. Several analytical methods, mainly high-performance liquid chromatography with electrochemical amperometric detection, have been reported for the analysis of(More)
The vitreous humor (VH) is the largest component of the eye. It is a colorless, gelatinous, highly hydrated matrix that fills the posterior segment of the eye between the lens and retina in vertebrates. In VH, a diversity of proteins that can influence retinal physiology is present, including growth factors, hormones, proteins with transporter activity, and(More)