Partial purification and characterization of a peroxidase activity from human placenta

Abstract

Peroxidases can metabolize a variety of xenobiotics to reactive intermediates capable of binding to protein or DNA. The potential role of these enzymes in fetotoxicity has not been explored. In this study, the presence of peroxidase activity was observed in human term and pre-term placenta. Human term placental peroxidase activity (HTPP) was partially purified by concanavalin A affinity chromatography from CaCl2 extracts of the particulate fraction. HTPP appears to be a membrane-bound glycoprotein. Arachidonic acid-dependent oxidation of guaiacol was not observed, suggesting that the peroxidase activity was not due to prostaglandin synthase. Moreover, HTPP preparations were devoid of catalase and spectrally dissimilar from human haemoglobin, cytochrome P-450, eosinophil peroxidase and myloperoxidase, suggesting an endogenous origin. An Mr of approx. 119,000 was determined for HTPP by gel filtration. Cathodic slab-PAGE of cetyltrialkylammonium bromide-solubilized HTPP yielded two peroxidase-staining bands.

Role of Biotransformation in Conceptal Toxicity of Drugs and Other Chemicals

“…Peroxidase activity also occurs in animal embryos throughout gestation [199,204]. In contrast to uterine, the titer of embryonic enzyme increases logarithmically towards term [199]. (Table 5).…”

“…Although the physiological function of this enzyme is not firmly established, it is speculated that it provides protection from the infection of conceptal tissues by the invading microbes. In the mouse, nonpregnant uterus possesses high peroxidase titer which dramatically declines with advancing pregnancy [199]. Rat uterine peroxidase has been purified and characterized [200].…”

“…Since the striatal dopamine deficiency in the brain neurones is a hallmark of Parkinsonism, levodopa (L-dopa), which yields dopamine in vivo epoxide, an ultimate animal teratogen from (+) BPdiol by the rat uterine peroxidase. Peroxidase activity also occurs in animal embryos throughout gestation [199,204]. In contrast to uterine, the titer of embryonic enzyme increases logarithmically towards term [199].…”

Evaluation of Oxidative Stress during Toxoplasmosis in Pregnant Women

“…Glutathione peroxidase activity in serum was assayed colorimetrically, a method used by Nelson and Kulkarni. [11] Serum glutathione was measured by a modified procedure utilizing Ellman`s reagent and determined from a standard curve and expressed as nmol/mg protein. [11] Catalase activity was measured spectrophotometrically at 240 nm by calculating the rate of degradation of H2O2 as the substrate of the enzyme using the Aebi method.…”

“…[11] Serum glutathione was measured by a modified procedure utilizing Ellman`s reagent and determined from a standard curve and expressed as nmol/mg protein. [11] Catalase activity was measured spectrophotometrically at 240 nm by calculating the rate of degradation of H2O2 as the substrate of the enzyme using the Aebi method. [12] A molar absorption of 43.6 Mcm−1 was used to determine catalase activity.…”