title: Purification and Characterization of an Extracellular Acid Proteinase from the Ectomycorrhizal Fungus Hebeloma crustuliniforme.
abstract: Hebeloma crustuliniforme produced an extracellular acid proteinase in a liquid medium containing bovine serum albumin as the sole nitrogen source. The proteinase was purified 26-fold with 20% activity recovery and was shown to have a molecular weight of 37,800 (as indicated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis) and an isoelectric point of 4.8 +/- 0.2. The enzyme was most active at 50 degrees C and pH 2.5 against bovine serum albumin and was stable in the absence of substrates at temperatures up to 45 degrees C and pHs between 2.0 and 5.0. Pepstatin A, diazoacetyl-dl-norleucine methylester, metallic ions Fe and Fe, and phenolic acids severely inhibited the enzyme activity, while antipain, leupeptin, N-alpha-p-tosyl-l-lysine chloromethyl ketone, and trypsin inhibitor inhibited the activity moderately. The proteinase hydrolyzed bovine serum albumin and cytochrome c rapidly compared with casein and azocasein but failed to hydrolyze any of the low-molecular-weight peptide derivatives tested.
authors.affiliation: Department of Forest Science and Department of Plant Science, University of Alberta, Edmonton, Alberta, Canada T6G 2H1.
authors.forename: H
authors.initials: H
authors.lastname: Zhu
authors.forename: D C
authors.initials: DC
authors.lastname: Guo
authors.forename: B P
authors.initials: BP
authors.lastname: Dancik