ABSTRACT
Proteins equipped with flavin adenine dinucleotides (FAD) or flavin mononucleotides (FMN) are named flavoproteins and constitute about 1% of all existing proteins. They catalyze redox, acid-base and photochemical reactions in a variety of biochemical phenomena that goes from energy metabolism to DNA repair and light sensing. The versatility observed in flavoproteins is ultimately a balance of flavin intrinsic properties modulated by a protein environment. This thesis aims to investigate how flavoproteins work by systematic evaluating flavin properties and reactivity. In particular, the mechanism of fumarate reduction by the flavoenzyme fumarate reductase Fcc3 was determined. Electronic-structure calculations were used for this task based on rigorous calibration with experimental data and error assessment. Flavin properties at chemical accuracy were obtained with single reference coupled-cluster CCSD(T) calculations at the complete basis set limit. Density functional theory was demonstrated an excellent alternative with lower computational costs and slightly less accuracy. Flavin protonation and tautomerism were shown to be important modulators of flavin properties and reactivity, with the possibility of various tautomers existing at neutral pH. Regarding flavin redox properties, an analysis based on multiconfigurational wave function weights was proposed for categorizing flavin redox reactions as hydride or hydrogen-atom transfers. This analysis is an upgrade over traditional partial charges methods and can be applied not only to flavin reactions but to any protoncoupled electron transfer. In the investigation of the enzymatic mechanism of fumarate reduction, the reaction was determined as a nucleophilic addition by hydride transfer with carbanion formation. Fumarate reductase employs electrostatic catalysis in contrast to previous proposals of substrate straining and general-acid catalysis. Also, hydride transfer was shown to be vibronically adiabatic with low tunneling contribution. These findings give new insights into the mechanisms of fumarate reductases and provide a framework for future computational studies of flavoproteins in general. The analyses and benchmark studies presented can be used to build better models of properties and reactivity of flavins and flavoproteins
Proteínas equipadas com dinucleotídeos de flavina-adenina (FAD) e mononucleotídeos de flavina (FMN) são chamadas flavoproteínas e constituem cerca de 1% de todas as proteínas existentes. Elas catalisam reações redox, ácido-base e fotoquímicas numa variedade de fenômenos bioquímicos que vão desde o metabolismo energético até reparo de DNA e captação de luz. A versatilidade observada em flavoproteínas é em última instância um balanço das propriedades intrínsecas de flavinas moduladas por um ambiente proteico. Esta tese busca investigar como flavoproteínas funcionam através de avaliações sistemáticas de propriedades e reatividade de flavinas. Em particular, o mecanismo de redução de fumarato pela flavoenzima fumarato redutase Fcc3 foi determinado. Cálculos de estrutura eletrônica foram usados para esta tarefa com base em rigorosa calibração com dados experimentais e avaliação de erros. As propriedades de flavinas foram determinadas com acurácia química com cálculos monoconfiguracionais de coupled-cluster CCSD(T) no limite de conjunto base completo. A teoria do funcional da densidade mostrou-se uma alternativa excelente com menor custo computacional e um pouco menos de acurácia. Protonação e tautomerismo de flavinas mostraram-se moduladores importantes de suas propriedades e reatividade, com a possibilidade de vários tautômeros existirem em pH neutro. Em relação às propriedades redox de flavinas, uma análise baseada nos pesos de funções de onda multiconfiguracionais foi proposta para categorizar as reações redox de flavinas como transferências de hidreto ou hidrogênio. Esta análise é uma melhoria em relação aos métodos tradicionais de cargas parciais e pode ser aplicada não apenas para reações de flavinas mas para qualquer transferência de próton acoplada a elétrons. Na investigação do mecanismo enzimático de redução de fumarato, a reação foi designada como uma adição nucleofílica por transferência de hidreto e formação de carbânion. A fumarato redutase usa catálise eletrostática diferentemente de prospostas anteriores envolvendo distorção do substrato e catálise ácida geral. Além disso, a transferência de hidreto mostrou-se vibronicamente adiabática com pouca contribuição de tunelamento. Estas descobertas abrem novas perspectivas sobre os mecanismos de fumarato redutases e fornecem uma base para estudos computacionais futuros sobre flavoproteínas em geral. As análises e estudos comparativos apresentados podem ser usados para construir melhores modelos para propriedades e reatividade de flavinas e flavoproteínas
Subject(s)
Comparative Study , Flavins/analysis , Flavoproteins/analysis , Calculi/chemistry , Static Electricity/adverse effects , FumaratesABSTRACT
The relationship between the levels of renalase and changes in proteinuria,hypertension,renal function,renal tubular epithelial cell apoptosis and B-cell lymphoma-2 (Bcl-2) expression was investigated in patients (chronic nephritis,primary nephrotic syndrome or other kidney disease) that underwent renal biopsy.The study group comprised 72 patients undergoing renal biopsy.Patient profiles and renal function were collected.Concentrations of renalase and Bcl-2 were measured by immunohistochemistry.Tubular injury was detected by periodic acid Schiff staining (PAS) and renal tubular epithelial cell apoptosis was assessed by TUNEL assay.The expression of renalase was significantly lower in renal biopsy specimens than in normal kidney tissues.There was a positive linear relationship between renalase and some serum and cardiac indices;a negative correlation was found between age,eGFR,Ccr and 24-h urinary protein.Renal tubule injury index and tubular epithelial cell apoptosis index showed a negative linear correlation with renalase.The results showed that renalase probably increased the expression of Bcl-2.By two independent samples t-test,renalase levels were significantly increased in the non-hypertension group than in the hypertension group.One-way ANOVA showed that renalase expression was higher in samples with Lee's grade Ⅲ than in those with Lee's grade V.The expression of renalase was significantly decreased in patients who underwent renal biopsy,and was also associated with blood and renal function.The research proved that renalase may reduce renal tubular injury and apoptosis of renal tubular epithelial cells through the mitochondrial apoptosis pathway,finally achieving the purpose of delaying the progress of renal failure.
ABSTRACT
The relationship between the levels of renalase and changes in proteinuria,hypertension,renal function,renal tubular epithelial cell apoptosis and B-cell lymphoma-2 (Bcl-2) expression was investigated in patients (chronic nephritis,primary nephrotic syndrome or other kidney disease) that underwent renal biopsy.The study group comprised 72 patients undergoing renal biopsy.Patient profiles and renal function were collected.Concentrations of renalase and Bcl-2 were measured by immunohistochemistry.Tubular injury was detected by periodic acid Schiff staining (PAS) and renal tubular epithelial cell apoptosis was assessed by TUNEL assay.The expression of renalase was significantly lower in renal biopsy specimens than in normal kidney tissues.There was a positive linear relationship between renalase and some serum and cardiac indices;a negative correlation was found between age,eGFR,Ccr and 24-h urinary protein.Renal tubule injury index and tubular epithelial cell apoptosis index showed a negative linear correlation with renalase.The results showed that renalase probably increased the expression of Bcl-2.By two independent samples t-test,renalase levels were significantly increased in the non-hypertension group than in the hypertension group.One-way ANOVA showed that renalase expression was higher in samples with Lee's grade Ⅲ than in those with Lee's grade V.The expression of renalase was significantly decreased in patients who underwent renal biopsy,and was also associated with blood and renal function.The research proved that renalase may reduce renal tubular injury and apoptosis of renal tubular epithelial cells through the mitochondrial apoptosis pathway,finally achieving the purpose of delaying the progress of renal failure.
ABSTRACT
Objective To analyze the clinical and imaging features of 2 siblings with leukoencephalopathy due to NADH dehydrogenase (ubiquinone)flavoprotein 2 (NDUFV2) gene mutation,in order to better understand and diagnose it earlier.Methods Clinical and follow-up data of the proband and his brother were collected.Clinical features including symptoms,signs and cranial magnetic resonance imaging (MRI) were analyzed,and 2 patients were followed up for a long time.Sanger sequencing,targeted next generation sequencing,and whole exome sequencing were performed to identify potential genetic variations in the 2 patients and their parents.Results (1) Clinical characteristics and follow-up:ages of onset were 4 months and 1 year respectively.Both of the patients presented rapid motor regression hyperinyotonia,positive pathological character.During the follow-up the condition became stable,motor function and cognition improved gradually after cocktail therapy.(2) Brain MRI of the 2 patients showed prominent abnormalities in deep cerebral white matter,presenting T1 hypointense,T2 and fluid attenuated inversion recovery (FLAIR) hyperintense in the periventricular area.FLAIR images revealed that the abnormal white matter was partially rarefied and cavitated.Diffusion weighted images (DWI) showed high signals along the periphery of the involved areas.The follow-up MRI showed the cavitation still existed and even expanded,and DWI showed regional linear or spotty high signals around the original lesions.(3) Novel mutations in NDUFV2 gene,c.467T>A and c.404G>C,were identified in proband and his brother.The former inherited from his father,while the latter inherited from his mother,which was the new mutation not reported in the international.Conclusions The clinical features of the brothers presented subacute leukoencephalopathy with relatively stable or improved outcome.This was distinctive from the phenotypic features reported in 12 cases with hypertrophic cardiomyopathy or Leigh syndrome.The finding expanded the phenotypic spectrum of NDUFV2 mutations.Pathogenic gene of these patients which is the basis of genetic counseling for this family was determined.
ABSTRACT
Background: 3-Ketosteroid-∆¹-dehydrogenase (KSDD), a flavoprotein enzyme, catalyzes the bioconversion of 4-androstene-3,17-dione (AD) to androst-1,4-diene-3,17-dione (ADD). To date, there has been no report about characterization of KSDD from Mycobacterium neoaurum strains, which were usually employed to produce AD or ADD by fermentation. Results: In this work, Corynebacterium crenatum was chosen asa new host for heterologous expression of KSDD from M. neoaurum JC-12 after codon optimization of the KSDD gene. SDS-PAGE and western blotting results indicated that the recombinant C. crenatum harboring the optimized ksdd (ksdd n) gene showed significantly improved ability to express KSDD. The expression level of KSDD was about 1.6-fold increased C. crenatum after codon optimization. After purification of the protein, we first characterized KSDD from M. neoaurum JC-12, and the results showed that the optimum temperature and pH for KSDD activity were 30°C and pH 7.0, respectively. The Km and Vmax values of purified KSDD were 8.91 µM and 6.43 mM/min. In this work, C. crenatum as a novel whole-cell catalyst was also employed and validated for bioconversion of AD to ADD. The highest transformation rate of AD to ADD by recombinant C. crenatum was about 83.87% after 10 h reaction time, which was more efficient than M. neoaurum JC-12 (only 3.56% at 10 h). Conclusions: In this work, basing on the codon optimization, overexpression, purification and characterization of KSDD, we constructed a novel system, the recombinant C. crenatum SYPA 5-5 expressing KSDD, to accumulate ADDfromADefficiently. This work provided new insights into strengthening sterol catabolism by overexpressing the key enzyme KSDD, for efficient ADD production.
Subject(s)
Androstadienes/metabolism , Corynebacterium/enzymology , Mycobacterium/enzymology , Oxidoreductases/metabolism , Codon , Recombinant ProteinsABSTRACT
Multiple acyl-CoA dehydrogenase deficiency (MADD) is a common inborn error of fatty-acid metabolism characterized by vomiting, acidosis and lipid storage myopathy, and the clinical manifestations of MADD are highly heterogeneous. MADD can be diagnosed by the elevation of multiple acyl-carnitine in blood and glutaric acid or other organic acid in urine. The neonatal-onset patients have severe symptoms and poor prognosis. However, oral riboflavin supplementation (can completely rescue) ameliorate the clinical and laboratory disorders rapidly especially to the riboflavin responsive MADD. Additionally, patients not sensitive to riboflavin should also take low lipid, low protein and high carbonhydrate diet besides riboflavin.