title: A laccase with antiproliferative and HIV-I reverse transcriptase inhibitory activities from the mycorrhizal fungus Agaricus placomyces.
abstract: A novel 68 kDa laccase was purified from the mycorrhizal fungus Agaricus placomyces by utilizing a procedure that comprised three successive steps of ion exchange chromatography and gel filtration as the final step. The monomeric enzyme exhibited the N-terminal amino acid sequence of DVIGPQAQVTLANQD, which showed only a low extent of homology to sequences of other fungal laccases. The optimal temperature for A. placomyces laccase was 30°C, and optimal pH values for laccase activity towards the substrates 2,7'-azinobis[3-ethylbenzothiazolone-6-sulfonic acid] diammonium salt (ABTS) and hydroquinone were 5.2 and 6.8, respectively. The laccase displayed, at 30°C and pH 5.2, K(m) values of 0.392 mM towards hydroquinone and 0.775 mM towards ABTS. It potently suppressed proliferation of MCF 7 human breast cancer cells and Hep G2 hepatoma cells and inhibited human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) activity with an IC(50) of 1.8 μM, 1.7 μM, and 1.25 μM, respectively, signifying that it is an antipathogenic protein.
authors.affiliation: Key Laboratory of Urban Agriculture (North) of Ministry of Agriculture, Beijing University of Agriculture, Beijing 102206, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Sun
authors.forename: Qing-Jun
authors.initials: QJ
authors.lastname: Chen
authors.forename: Qing-Qin
authors.initials: QQ
authors.lastname: Cao
authors.forename: Ying-Ying
authors.initials: YY
authors.lastname: Wu
authors.forename: Li-Jing
authors.initials: LJ
authors.lastname: Xu
authors.forename: Meng-Juan
authors.initials: MJ
authors.lastname: Zhu
authors.forename: Tzi-Bun
authors.initials: TB
authors.lastname: Ng
authors.forename: He-Xiang
authors.initials: HX
authors.lastname: Wang
authors.forename: Guo-Qing
authors.initials: GQ
authors.lastname: Zhang
mesh_terms: D000364:Agaricus / Q000201:enzymology*; D049109:Cell Proliferation / Q000187:drug effects; D005656:Fungal Proteins / Q000378:metabolism / Q000494:pharmacology; D054303:HIV Reverse Transcriptase / Q000037:antagonists & inhibitors*; D056945:Hep G2 Cells; D006801:Humans; D042845:Laccase / Q000008:administration & dosage* / Q000378:metabolism*; D061986:MCF-7 Cells; D009374:Neoplasms, Experimental / Q000188:drug therapy* / Q000473:pathology; D018894:Reverse Transcriptase Inhibitors / Q000737:chemistry*
chemical_list: D005656:Fungal Proteins; D018894:Reverse Transcriptase Inhibitors; D042845:Laccase; C514824:reverse transcriptase, Human immunodeficiency virus 1; D054303:HIV Reverse Transcriptase