Evidence of a coupled mechanism between monoamine oxidase and peroxidase in the metabolism of tyramine by rat intestinal mitochondria
摘要:
The relationship between monoamine oxidase (EC 1.4.3.4; MAO) and peroxidase (EC 1.11.1.7; POD) in the metabolism of tyramine was investigated using the crude mitochondrial fraction of rat intestine. When tyramine was incubated with mitochondria, the formation of the peroxidase-catalysed oxidation product, 2,2'-dihydroxy-5,5'-bis(ethylamino)diphenyl (dityramine), identified by mass spectrometric analysis, was monitored spectrophotometrically. After an initial lag time, the formation rate of dityramine was linear up to 2 hr, amounting to 17 nmol X hr(-1) X mg protein(-1). A similar value was found for the oxidative deamination of tyramine catalysed by intestinal MAO. Either 10(-3) M clorgyline or 10(-3) M NaCN suppressed this reaction by completely inhibiting MAO or POD, respectively. In the former case, however, addition of H2O2 to the incubation mixture promptly started the reaction. Selective inhibition of MAO-A and MAO-B was achieved with 3 X 10(-7) M clorgyline and 3 X 10(-7) M deprenyl, respectively, and the formation rate of dityramine decreased in a corresponding manner. Preincubation with histamine or spermidine reduced the lag time without affecting the steady-state reaction rate. Higher levels of dityramine were also detected in vivo in rat intestine after oral administration of tyramine. These results indicate that the peroxidase-dependent metabolism of tyramine in the gut may be driven by H2O2 produced by MAO activities and that MAO-A is mainly responsible for this process, as well as for the oxidative deamination of tyramine. (C) 1998 Elsevier Science Inc.
Regulative peroxidase activity of DNA-linked hemin by graphene oxide for fluorescence DNA sensing
作者:Quanbo Wang、Nan Xu、Jianping Lei、Huangxian Ju
DOI:10.1039/c4cc02273d
日期:——
The inhibition effect of graphene oxide toward the peroxidase activity of DNA-linked hemin was identified for fluorescence DNA sensing.
翻译结果:鉴于荧光DNA传感,氧化石墨烯对DNA-血红素连接的过氧化物酶活性的抑制作用被确定。
Exploitation of Luminescent Lanthanide Nanoparticles for a Sensitivity-Enhanced ELISA Detection Method
作者:Ali A. Kassir、Clémence Cheignon、Loïc J. Charbonnière
DOI:10.1021/acs.analchem.3c04821
日期:2024.2.6
on the photoluminescenceproperties of dye-sensitized lanthanide nanoparticles (Ln NPs) was developed for enzyme-linked immunosorbent assays (ELISAs). In this method, the horseradish peroxidase (HRP) enzyme catalyzes the oxidation of phenol derivatives in the presence of hydrogen peroxide, providing dimers that are able to interact with the Ln NP surface and to efficiently photosensitize the Ln ions
The method described characterizes each DNA segment to be mapped by cleaving it to produce DNA fragments which are then end labeled with a reporter(s) specific to the end nucleotides of each fragment. The labeled fragments are again cleaved to produce short fragments which are separated according to size. The short fragments are analyzed as to reporter identity and size which is indicative of the character of each fragment. By derivatizing the cleaved ends of the primary cleaved fragments, the labeling may be delayed until the second cleavage. Prior to labeling the derivatized fragments, all underivatized fragments are removed, the derivatized fragments being immobilized.
所述方法通过裂解 DNA 片段产生 DNA 片段,然后用特异于每个片段末端核苷酸的报告物对其进行末端标记,从而确定要绘制的每个 DNA 片段的特征。标记后的片段再次裂解,产生短片段,并根据大小将其分离。对短片段进行分析,以确定报告基因的特性和大小,这表明了每个片段的特性。通过对初级裂解片段的裂解末端进行衍生处理,可将标记延迟到第二次裂解。在对衍生片段进行标记之前,先移除所有未充分活化的片段,然后固定衍生片段。