290. Acid phosphatase activity in developing human placenta
About: This article is published in Journal of Steroid Biochemistry.The article was published on 1978-09-01. It has received 3 citation(s) till now. The article focuses on the topic(s): Acid phosphatase & Alkaline phosphatase.
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TL;DR: The presence of phosphodiesterase IV has been demonstrated in the human fetal brain, liver and placenta as early as in the 6th week of intrauterine development and enzyme activity in each tissue increases with gestation, being maximum at 18-21 wk and then decreases.
Abstract: The presence of phosphodiesterase IV has been demonstrated in the human fetal brain, liver and placenta as early as in the 6th week of intrauterine development. The enzyme activity in each tissue increases with gestation, being maximum at 18–21 wk and then decreases. The K m values of this enzyme for bis-( p -nitrophenyl)-phosphate hydrolysis in the brain, liver and placenta are 2.94 mM, 1.47 mM and 1.66 mM, respectively. Presence of sulfhydryl group in the active center of the placental enzyme has been demonstrated with the help of cationic study. EDTA inhibits the enzyme in all the three tissues. Effect of concanavalin A reveals the absence or unexposition of glucose, mannose and N -acetylglucosamine moieties in the active site of the enzyme in each of the three tissues. Maximum enzyme activity has been found to be localized in the soluble supernatant fraction obtained on centrifuging the brain and liver homogenate at 105,000 × g and in 20,000 × g pellet of the placenta.
11 citations
TL;DR: Alkaline phosphatase from a late stage of gestation appeared to be almost heat-stable and an appreciable part of 5’-nucleotidase was also resistant to heat inactivation and this fraction varied with gestational age of the tissue.
Abstract: Activities and a few properties of alkaline phosphatase and 5’-nucleotidase were compared in the developing human placenta. Both the enzymes were mostly membrane-bound and displayed similar developmental patterns with the highest activities at 24/26 weeks of the placenta. L-Phenylalanine, L-tryptophan and L-leucine were inhibitors of alkaline phosphatase, whereas they had no effect on the 5’-nucleotidase. Alkaline phosphatase from a late stage of gestation appeared to be almost heat-stable. An appreciable part of 5’-nucleotidase was also resistant to heat inactivation and this fraction varied with gestational age of the tissue. For both the enzymes, Vmax changed without alteringK
m values with periods of gestation. Ca2+, Mg2+ and Mn2+ ions stimulated the alkaline phosphatase activity and Hg2+, Zn2+, Cu2+, Ni2+ were inhibitory. 5’-Nucleotidase was not activated by any of these cations. EDTA and Concanavalin A inhibited both the enzymes, although the extent of inhibition was different and also varied with gestation.
4 citations
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...Similar observations have also been reported with ∝-glucosidase (Thanavala et al., 1974), acid phosphatase (Kushari et al., 1978), acetyl cholinesterase (Sastry et al., 1976) and ATPase (Chakraborti and Mukherjea, 1980)....
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TL;DR: The enzyme activities in the placenta increase steadily with gestational age until the 18th to 21st week, and decrease in the second half of pregnancy, and Vmax of the enzymes decline at term.
Abstract: Activities and some properties of microsomal ATPases have been studied in developing human placenta. The enzyme activities (Na+ + K+ + Mg2+, Mg2+, and Ca2+ dependent) in the placenta increase steadily with gestational age until the 18th to 21st week, and decrease in the second half of pregnancy. Mg2+-dependent and Na+ + K+ + Mg2+-dependent ATPases possess nearly the same Km (apparent) for ATP, while the Ca2+-dependent enzyme shows a different one. Mg2+-dependent ATPase shows higher substrate affinity than Ca2+-dependent ATPase, although the Vmax of the Mg2+-dependent enzyme is lower than that of the latter. However, for each enzyme, the Km remains almost constant and Vmax varies during ontogenic development. Vmax of the enzymes decline at term. The enzymes are heat-labile, unaffected by amino acids, namely, L-phenylalanine, L-leucine, and L-tryptophan, and deoxycholate inhibits the enzyme activities by about 50%.
1 citations