Partial characterization of proteolytic activity in Giardia duodenalis purified proteins

This report describes a preliminary characterization of proteolytic activity of proteins isolated from lysate of Giardia trophozoites of an axenic Brazilian strain. Fractions obtained by high-performance liquid chromatography (FPLC) were tested in SDS-polyacrylamide gel for the protein profiles, and the proteases activity was analyzed using gelatin impregnated SDS-PAGE. The proteases characterization was based on inhibition assays employing synthetic inhibitors for cysteine (E-64, IAA), serine (PMSF, TPCK, TLCK, and elastatinal), metalo (EDTA) and aspartic (pepstatin) proteases. Among thirty eluted fractions, polypeptide bands were observed in eight of them, however, proteolytic activity was detected in four ones (F23, F24, F25 and F26). Protein profiles of these fractions showed a banding pattern composed by few bands distributed in the migration region of 45 to < 18 kDa. The zymograms revealed proteolytic activity in all the four fractions assayed, mainly distributed in the migration region of 62 to 35 kDa. Among the profiles, the main pronounced zones of proteolysis were distinguished at 62, 55, 53, 50, 46 and 40 kDa. In inhibition assays, the protease activities were significantly inhibited by cysteine (E-64) and serine proteases (TPCK, TLCK and elastatinal) inhibitors. Gels incubated with other cysteine and serine protease inhibitors, IAA and PMSF, respectively, showed a decrease in the intensity of hydrolysis zones. Indeed, in the assays with the inhibitors EDTA for metalloproteases and pepstatin for aspartic proteases, none inhibition was detected against the substrate. These observations are relevants, especially if we consider that to define the real role of the proteases in host-parasite interaction, the purification of these enzymes for detailed studies may be warranted.

Analysis of Synaptic Proteins in the Cerebrospinal Fluid as a New Tool in the Study of Inborn Errors of Neurotransmission

Abstract In a few rare diseases, specialised studies in cerebrospinal fluid (CSF) are required to identify the underlying metabolic disorder. We aimed to explore the possibility of detecting key synaptic proteins in the CSF, in particular dopaminergic and gabaergic, as new procedures that could be useful for both pathophysiological and diagnostic purposes in investigation of inherited disorders of neurotransmission. Dopamine receptor type 2 (D2R), dopamine transporter (DAT) and vesicular monoamine transporter type 2 (VMAT2) were analysed in CSF samplesfrom 30 healthy controls (11 days to 17 years) by western blot analysis. Because VMAT2 was the only protein with intracellular localisation, and in order to compare results, GABA vesicular transporter, which is another intracellular protein, was also studied. Spearman’s correlation and Student’s t tests were applied to compare optical density signals between different proteins. All these synaptic proteins could be easily detected and quantified in the CSF. DAT, D2R and GABA VT expression decrease with age, particularly in the first months of life, reflecting the expected intense synaptic activity and neuronal circuitry formation. A statistically significant relationship was found between D2R and DAT expression, reinforcing the previous evidence of DAT regulation by D2R. To our knowledge, there are no previous studies on human CSF reporting a reliable analysis of these proteins. These kinds of studies could help elucidate new causes of disturbed dopaminergic and gabaergic transmission as well as understanding different responses to L-dopa in inherited disorders affecting dopamine metabolism. Moreover, this approach to synaptic activity in vivo can be extended to different groups of proteins and diseases.

Expressão em Escherichia coli de antigénios do Cell fusing agent virus (Flaviviridae: Flavivirus) como proteína de fusão

RESUMO: O Cell Fusing Agent Vírus (CFAV), considerado como o primeiro “flavivírus específicos de insectos” (ISF), parece estar exclusivamente adaptado aos seus hospedeiros, não replicando em células de vertebrados. Apesar de ter sido identificado há mais de três décadas (1975), a verdade é que muito pouco se conhece sobre a sua biologia. Dado o seu parentesco filogenético com alguns outros flavivírus encontrados naturalmente em mosquitos de diferentes géneros colhidos em diferentes regiões do globo, este vírus poderá ser usado como modelo para o estudo de ISF. No entanto, necessitam do desenvolvimento de ferramentas básicas, tais como clones moleculares ou baterias de soros contendo anticorpos que reconheçam uma ou mais proteínas codificadas pelo genoma viral, produzidas, por exemplo, a partir de antigénios virais produzidos de forma recombinante. Com este trabalho pretendeu-se a optimização de protocolos que permitiram a expressão e purificação parcial de quatro proteínas [duas proteínas estruturais (C e E) e duas não estruturais (NS3hel e NS5B)] do CFAV em E. coli, todas elas produzidas como proteínas de fusão com “caudas” (tags) de hexahistidina nos seus extremos carboxilo. Para a expansão do CFAV foram utilizadas células Aedes albopictus (C6/36). Após a realização da extracção do RNA viral e a obtenção de cDNA, procedeu-se amplificação, por RT-PCR, das regiões codificantes das proteínas C, E, NS3hel e NS5B, utilizando primers específicos. Os quatro fragmentos de DNA foram independentemente inseridos no vector pJTE1.2/blunt usando E. coli NovaBlue como hospedeira de clonagem e, posteriormente, inseridos em vectores de expressão pET-28b e pET-29b usando E. coli BL21(DE3)pLysS e Rosetta(DE3)pLysS como hospedeiras de expressão. Após da indução, expressão e purificação das proteínas recombinantes C, E, NS3hel e NS5B, foi confirmada a autenticidade destas proteínas produzidas através do método Western Blot com um anticorpo anti-histidina. --------- ABSTRACT: The Cell Fusing Agent virus (CFAV) considered as the first "insect- specific flavivirus" (ISF) and seems to be uniquely adapted to their hosts, not replicating in vertebrate cells. Although it has been known for more than three decades (1975), the truth is very little is known about its biology. Given its close phylogenetic relationship with other flavivirus naturally circulating in various genera of mosquitoes collected from different regions of the globe, this virus could be used as a model for the study of ISF. However, such studies require the development of experimental basic tools, such as molecular clones or serum batteries containing antibodies that recognize one or more proteins encoded by the viral genome, produced, for example, from viral antigens recombinant produced. In this work, we carried out the optimization of protocols that allowed the expression and partial purification of four proteins [two structural proteins (C and E) and two nonstructural proteins (NS3hel and NS5B)] CFAV in E. coli as fusion protein for c-terminal hexahistidine tags. For the expansion of the CFAV we used Aedes albopictus (C6/36) cells. After completion of the viral RNA extraction and cDNA obtained, amplification of the coding regions of the C, E, NS5B and NS3hel proteins was carried out by RT-PCR using specific primers. The four DNA fragments were independently inserted into the vector pJTE1.2/blunt using E. coli NovaBlue as cloning host and then inserted into expression vectors pET-28b and pET-29b using E. coli BL21(DE3)pLysS and Rosetta(DE3)pLysS as expression host. After induction, expression and purification of recombinant C, E, NS3hel and NS5B proteins Western Blot analyses with an anti-histidine antibody confirmed the authenticity of these proteins produced.

The role of Di-iron proteins in pathogen resistance

Dissertation presented to obtain the Ph.D. degree in Biochemistry

Artefacts induced on c-type haem proteins by electrode surfaces

J Biol Inorg Chem (2011) 16:209–215 DOI 10.1007/s00775-010-0717-z

Kinetics studies of the superoxide-mediated electron transfer reactions between rubredoxin-type proteins and superoxide reductases

J Biol Inorg Chem (2006) 11: 433–444 DOI 10.1007/s00775-006-0090-0

Tauroursodeoxycholic acid prevents Bax-induced membrane perturbation and cytochrome C release in isolated mitochondria

Biochemistry, 2003, 42 (10), pp 3070–3080 DOI: 10.1021/bi026979d

Integrated study by NMR and X-ray Crystallography on the analysis of the molecular interactions in heme-binding proteins

Dissertação para obtenção do Grau de Doutor em Bioquímica, Especialidade Bioquímica Estrutural

Cerebrospinal Fluid Synaptic Proteins as Useful Biomarkers in Tyrosine Hydroxylase Deficiency

Tyrosine hydroxylase (TH) deficiency is an inborn error of dopamine biosynthesis and a cause of early parkinsonism. Two clinical phenotypes have been described. Type “B”: early onset severe encephalopathy; type “A”: later onset, less severe and better response to L-dopa. We aimed to study the expression of several key dopaminergic and gabaergic synaptic proteins in the cerebrospinal fluid (CSF) of a series of patients with TH deficiency and their possible relation with the clinical phenotype and response to L-DOPA. Dopamine transporter (DAT), D2-receptor and vesicularmonoamine transporter (VMAT2)weremeasured in the CSF of 10 subjectswith THdeficiency byWestern blot analysis. In 3 patients, data of pre- and post-treatmentwith L-DOPA were available, and in one of them, GABA vesicular transporter was determined. Results were compared to an age-matched control population. The concentration of D2-receptors in CSFwas significantly higher in patients with TH deficiency than in controls. Similarly, DAT and vesicular monoamine transporter type 2 were up-regulated. Studies performed before LDOPA, and on L-DOPA therapy showed a paradoxical response with D2 receptor expression increase as L-Dopa doses and homovanillic concentration gradually raised in a B phenotype patient. The opposite results were found in two patients with A phenotype. However, this is a very small sample, and further studies are needed to conclude robust differences between phenotypes. Synaptic proteins are detectable in the CSF and their quantification can be useful for understanding the pathophysiology of neurotransmitter defects and potentially to adjust and personalize treatments in the future.

Renal Transplantation in HIV-Infected Patients: The First Portuguese Review

INTRODUCTION: With the introduction of combination antiretroviral therapy (cART), prognosis of human immunodeficiency virus (HIV) infection has been improved and kidney transplantation (KT) in HIV-positive patients became possible. METHODS: We reviewed the demographic, clinical, laboratory, and therapeutic data of all the HIV-infected patients who underwent KT between 2009 (first KT in Portugal in a HIV-infected patient) and May 2014. Case accrual was through all Portuguese KT centers where a KT in an HIV-infected patient was performed. Patients were transplanted following the American and Spanish guideline recommendations that included maintenance on cART, undetectable plasma HIV RNA copies, and absolute CD4 counts of ≥ 200 cells/μL in the last 6 months. RESULTS: Fourteen KT were performed on men and 3 on women. The mean age of patients at the time of transplantation was 49.9 ± 11.7 years. HIV status was known for 12 ± 5 years. Eight patients had AIDS in the past and all patients received grafts from deceased donors. Twelve patients (64.7%) underwent induction therapy with basiliximab and 2 patients experienced early graft loss. In 2 patients, humoral rejection was diagnosed and in 3 patients, cellular rejection. Two patients died and an additional patient had early graft loss. CONCLUSION: KT is a possible, but challenging, renal replacement therapy in selected HIV-positive patients. Even in those with AIDS criteria in the past, when the disease is controlled, and after the reconstitution of the immune system with cART, KT can be performed. Nevertheless, the risk-benefit ratio for each patient needs to be taken in consideration.

Production and Characterization of the biological activity of peptides obtained via hydrolysis from whey proteins by cardosins

Dissertation presented to obtain the Ph.D degree in Biochemistry, Engineering and Technological Sciences

Cyanobacterial and Protozoan Flavodiiron Proteins are nitric oxide and/or dioxygen reductases

Dissertation presented to obtain the Ph.D degree in Biochemistry.