title: The growth factor from plerocercoids of Spirometra mansonoides is both a growth hormone agonist and a cysteine proteinase.
abstract: Plerocercoids of the tapeworm Spirometra mansonoides produce a substance that stimulates growth of experimental hosts. We report purification of plerocercoid growth factor (PGF) to homogeneity by a process involving isolation and solubilization of plerocercoid membranes, isoelectric point selection by chromatofocusing chromatography or preparative isoelectric focusing, and anion-exchange chromatography. A radioreceptor assay (RRA) for human growth hormone (hGH) was used to detect PGF and purity of the 27.5-kDa protein was judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Proteolytic activity was detected in the 27.5-kDa protein by gelatin substrate PAGE. Characterization of PGF as a neutral cysteine proteinase was based on substrate and inhibitor specificities and dependence on pH and thiol-containing reagents. The association of hGH agonist and proteinase activities was shown by comparing RRA and hydrolytic activities in the presence and absence of the cysteine proteinase inhibitor E-64.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha 68198-6545, USA.
authors.forename: K
authors.initials: K
authors.lastname: Phares
authors.forename: J
authors.initials: J
authors.lastname: Kubik
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001667:Binding, Competitive; D002852:Chromatography, Ion Exchange; D003546:Cysteine Endopeptidases / Q000302:isolation & purification* / Q000378:metabolism / Q000494:pharmacology; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D013006:Growth Hormone / Q000819:agonists*; D006133:Growth Substances / Q000302:isolation & purification* / Q000378:metabolism / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007525:Isoelectric Focusing; D007526:Isoelectric Point; D008565:Membrane Proteins / Q000737:chemistry / Q000302:isolation & purification; D051379:Mice; D008969:Molecular Sequence Data; D008970:Molecular Weight; D011869:Radioligand Assay; D013146:Spirometra / Q000737:chemistry* / Q000201:enzymology; D013379:Substrate Specificity
chemical_list: D015853:Cysteine Proteinase Inhibitors; D006133:Growth Substances; D008565:Membrane Proteins; D013006:Growth Hormone; D003546:Cysteine Endopeptidases