Isolation and characterization of Dipeptidyl Peptidase IV from human placenta

  • Human placenta is surprisingly rich in post-proline dipeptidyl peptidase activity. Among various cell fractions, microsomes have the highest specific activity. A homogeneous enzyme preparation is obtained in a six-step purification procedure. The final preparation appears homogeneous upon dodecyl sulfate electrophoresis, but analytical isoelectric focussing reveals various active bands with isoelectric points in the range of pH 3 - 4. The enzyme is a glycoprotein containing about 30% carbohydrate. Treatment with neuraminidase lowers the isoelectric points but does not reduce the heterogeneity of the band pattern. The subunit molecular weight is 120000 as estimated by dodecyl sulfate electrophoresis, whereas Mr of the native enzyme is > 200000, as can be concluded from gel filtration experiments. The purified dipeptidyl peptidase cleaves various synthetic and natural peptides, including substance P, kentsin, casomorphin and a synthetic renin inhibitor. In general, the specificity of the placenta peptidase is similar to that ofHuman placenta is surprisingly rich in post-proline dipeptidyl peptidase activity. Among various cell fractions, microsomes have the highest specific activity. A homogeneous enzyme preparation is obtained in a six-step purification procedure. The final preparation appears homogeneous upon dodecyl sulfate electrophoresis, but analytical isoelectric focussing reveals various active bands with isoelectric points in the range of pH 3 - 4. The enzyme is a glycoprotein containing about 30% carbohydrate. Treatment with neuraminidase lowers the isoelectric points but does not reduce the heterogeneity of the band pattern. The subunit molecular weight is 120000 as estimated by dodecyl sulfate electrophoresis, whereas Mr of the native enzyme is > 200000, as can be concluded from gel filtration experiments. The purified dipeptidyl peptidase cleaves various synthetic and natural peptides, including substance P, kentsin, casomorphin and a synthetic renin inhibitor. In general, the specificity of the placenta peptidase is similar to that of post-proline dipeptidyl peptidase from other sources. Phenylalanylprolyl-P-naphthylamide (Km = 0.02 mM, I/ = 92 Ujmg) is the best substrate among various synthetic peptide derivatives. Only peptides with a free N-terminal amino group and proline, hydroxyproline, or alanine in position 2 of the N-terminal sequence are cieaved. However, X-Pro-Pro- . . . structures, e. g. as in bradykinin, are not attacked. 1 mM bis-(6nitrophenyI)phosphate or 1 mM diisopropylfluorophosphate completely inactivate the peptidase within 30 min at 30°C (pH 8). The peptidase is also completely inhibited by 1 mM Zn²⁺ and by other heavy metals.show moreshow less

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Metadaten
Author details:Gerhard Paul PüschelORCiDGND, Rolf Mentlein, Eberhard Heymann
URN:urn:nbn:de:kobv:517-opus-45875
Publication series (Volume number):Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe (paper 114)
Publication type:Postprint
Language:English
Publication year:1982
Publishing institution:Universität Potsdam
Release date:2010/08/04
Source:European Journal of Biochemistry 126 (1982), 2, p. 359-365, DOI 10.1111/j.1432-1033.1982.tb06788.x, ISSN 0014-2956
Organizational units:Mathematisch-Naturwissenschaftliche Fakultät / Institut für Ernährungswissenschaft
DDC classification:5 Naturwissenschaften und Mathematik / 57 Biowissenschaften; Biologie / 570 Biowissenschaften; Biologie
License (German):License LogoKeine öffentliche Lizenz: Unter Urheberrechtsschutz
External remark:
first published in:
FEBS Journal - 126 (1982), 2, p. 359-365
ISSN: 0014-2956
doi: 10.1111/j.1432-1033.1982.tb06788.x
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