acid-phosphatase and ascorbate-2-phosphate

Topics: Acid Phosphatase; Ascorbic Acid; Benzidines; Chlorides; Chromogenic Compounds; Colorimetry; Fluorescent Dyes; Gold Compounds; Humans; Limit of Detection; Oxidation-Reduction; Rhodamines; Smartphone; Spectrometry, Fluorescence

Topics: Acid Phosphatase; Ascorbic Acid; Biomimetic Materials; Biosensing Techniques; Catalysis; Colorimetry; Hydrogen Peroxide; Limit of Detection; Nanostructures; Oxidoreductases

Mycobacterium tuberculosis (Mtb) SapM is a secreted virulence factor critical for intracellular survival of the pathogen. The role of SapM in phagosome maturation arrest in host macrophages suggests its potential as a drug target to assist in the clearance of tuberculosis infection. However, the mechanism of action of SapM at the molecular level remains unknown. In this study, we provide new insights into the mechanism of catalysis, substrate specificity and inhibition of SapM, and we identify the critical residues for catalysis and substrate binding. Our findings demonstrate that SapM is an atypical monoester alkaline phosphatase, with a serine-based mechanism of catalysis probably metal-dependent. Particularly relevant to SapM function and pathogenesis, is its activity towards PI(4,5)P

Topics: Acid Phosphatase; Antitubercular Agents; Ascorbic Acid; Bacterial Proteins; Catalysis; Catalytic Domain; Humans; Inhibitory Concentration 50; Mycobacterium tuberculosis; Phosphatidylinositols; Substrate Specificity; THP-1 Cells; Virulence

In this paper, we developed a sensitive fluorescence biosensor for tyrosinase (TYR) and acid phosphatase (ACP) activity detection based on nitrogen-doped graphene quantum dots (N-GQDs). Tyrosine could be catalyzed by TYR to generate dopaquinone, which could efficiently quench the fluorescence of N-GQDs, and the degree of fluorescence quenching of N-GQDs was proportional to the concentration of TYR. In the presence of ACP, l-Ascorbic acid-2-phosphate (AAP) was hydrolyzed to generate ascorbic acid (AA), and dopaquinone was reduced to l-dopa, resulting in the fluorescence recovery of the quenched fluorescence by dopaquinone. Thus, a novel fluorescence biosensor for the detection of TYR and ACP activity based on N-GQDs was constructed. Under the optimized experimental conditions, the fluorescence intensity was linearly correlated with the concentration of TYR and ACP in the range of 0.43-3.85 U mL

Topics: Acid Phosphatase; Ascorbic Acid; Benzoquinones; Biosensing Techniques; Dihydroxyphenylalanine; Fluorescence; Graphite; Humans; Limit of Detection; Monophenol Monooxygenase; Nitrogen; Quantum Dots; Sensitivity and Specificity

An enzyme electrode was prepared with acid phosphatase (ACP) for development of a new electric power generation system using ascorbic acid 2-phosphate (AA2P) as a fuel. The properties of the electrode were investigated with respect to biocatalytic dephosphorylation of AA2P and electrochemical oxidation of resulting ascorbic acid (AA). The enzyme electrode was fabricated by immobilization of ACP through amide linkage onto a self-assembled monolayer of 3-mercaptopropionic acid on a gold electrode. AA2P was not oxidized on a bare gold electrode in the potential sweep range from -0.1 to +0.5 V vs. Ag/AgCl. However, the enzyme electrode gave an oxidation current in citric buffer solution of pH 5 containing 10 mM of AA2P. The oxidation current began to increase at +0.2V, and reached to 5.0 μA cm(-2) at +0.5 V. The potential +0.2 V corresponded to the onset of oxidation of ascorbic acid (AA). These results suggest that the oxidation current observed with the enzyme electrode is due to AA resulting from dephosphorylation of AA2P. The oxidation current increased with increasing concentration of AA2P and almost leveled off at around the concentration of 5mM. Thus the enzyme electrode brought about biocatalytic conversion of AA2P to AA, followed by electrochemical oxidation of the AA. The oxidation current is likely to be controlled by the biocatalytic reaction.

Topics: Acid Phosphatase; Ascorbic Acid; Bioelectric Energy Sources; Biosensing Techniques; Electrochemical Techniques; Oxidation-Reduction; Triticum