VOPROSY MEDITSINSKOI KHIMII (ISSN 0042-8809)

Comparative characteristics of membrane bound and cytoplasmic monoamine oxidases in human placenta

   
Kirkel' A.Z., Tishchenko L.A., Aksenova L.N., Pekkel' V.A., Gorkin V.Z.
PubMed Id: 1750204
Year: 1991  Volume: 37  Issue: 4  Pages: 25-28
Catalytic and physico-chemical properties of human placental monoamine oxidases (MAO) were studied. Both forms of the enzyme, membrane-bound and soluble, exhibited similar properties: optimal activity at pH8.3, equal rate of inhibition with selective MAO inhibitors, identical substrate specificity (the best substrate--serotonin). Some specific differences were found only for cytoplasmic (soluble) MAO: lower affinity for substrates as compared with membrane-bound enzymes, reversible interaction with an inhibitor Lilly 51641 even after long-term preincubation, whereas the mitochondrial MAO bound Lilly 51641 irreversibly. The property of cytoplasmic MAO to form aggregates during storage and/or in gel filtration and concentration did not affect the main catalytic properties of soluble enzyme. Analysis of isoenzyme spectra of membrane-bound and cytoplasmic MAO by means of selective inhibitors and electrophoresis showed that MAO of the two types--A and B were detected in all the subcellular fractions studied. Subunits of MAO of the A type had molecular masses 62, 61 and 61 kDa and of MAO of the B type--51, 55 and 55 kDa in mitochondria, microsomes and cytosol, respectively.
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Kirkel', A. Z., Tishchenko, L. A., Aksenova, L. N., Pekkel', V. A., Gorkin, V. Z. (1991). Comparative characteristics of membrane bound and cytoplasmic monoamine oxidases in human placenta. Voprosy Meditsinskoi Khimii, 37(4), 25-28.
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