No abstract

Phlebia radiata strain BP-12-2, isolated from forest soil, decolorized fungal melanin and produced an extracellular laccase in culture. The enzyme was purified to homogeneity and characterized. It showed no absorption bands in the ultraviolet above 300 nm or visible regions. It differed from the reported laccases in substrate specificity, kinetic parameters, and NH2-terminal amino acid sequences.

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Eggshell membrane is a mechanically stable and insoluble cross-linked fibrous protein. Pseudomonas aeruginosa strain ME-4 synthesizes a metalloprotease that degrades the eggshell membrane. We cloned the encoding gene in Escherichia coli. The recombinant protease, over-expressed in E. coli, was inactive but addition of acetone to crude cell extracts restored the activity and removed many E. coli proteins. We purified the active, acetone-treated protease to homogeneity in a single chromatography step with 57% recovery. The recombinant protease partially hydrolyzed eggshell membrane and produced more soluble peptides and proteins than commercial elastase, α-chymotrypsin, and collagenase. The soluble peptides produced from hydrolyzed eggshell membrane inhibited angiotensin-I-converting enzyme activity. The degradation of eggshell membrane by the recombinant elastase could be applied to the production of soluble bioactive peptides.