Je. Mellon et Pj. Cotty, PURIFICATION AND PARTIAL CHARACTERIZATION OF AN ELASTINOLYTIC PROTEINASE FROM ASPERGILLUS-FLAVUS CULTURE FILTRATES, Applied microbiology and biotechnology, 46(2), 1996, pp. 138-142
A 23-kDa protein with elastinolytic activity was purified from Aspergi
llus flavus (NRRL 18543) culture filtrates by gel-filtration chromatog
raphy. Severe inhibition of the elastinolytic activity by 1,10-phenant
hrolene (5 mM) and EDTA (0.8 mM) indicated that the protein belongs to
the metallo class of pro teases. The isoelectric point was 9.0. Natur
al substrates susceptible to cleavage by this protease, in addition to
elastin, included cottonseed storage protein, collagen, ovalbumin and
bovine serum albumin. The 23-kDa protein was thermostable to 70 degre
es C and retained its elastinolytic activity in concentrated form at 4
degrees C for 6 months. Elastinolytic activity was initially secreted
into the culture medium as a 35-kDa protein, which was subsequently c
onverted to a 23-kDa protein, presumably through autolysis. This putat
ive proteolytic degradation product appears to be identical to the 23-
kDa protein recovered from the gel-filtration column. The 23-kDa prote
ase may confer selective advantage to the fungus in the extracellular
environment because of its temperature and pH stability and wide range
of potential natural protein substrates.