Purification, biochemical, and structural characterization of a novel fibrinolytic enzyme from Mucor subtilissimus UCP 1262.

Fibrinolytic proteases are enzymes that degrade fibrin. They provide a promising alternative to existing drugs for thrombolytic therapy. A protease isolated from the filamentous fungus Mucor subtilissimus UCP 1262 was purified in three steps by ammonium sulfate fractionation, ion exchange, and molecular exclusion chromatographies, and characterized biochemically and structurally. The purified protease exhibited a molecular mass of 20 kDa, an apparent isoelectric point of 4.94 and a secondary structure composed mainly of α-helices. Selectivity for N-succinyl-Ala-Ala-Pro-Phe-p-nitroanilide as substrate suggests that this enzyme is a chymotrypsin-like serine protease, whose activity was enhanced by the addition of Cu2+, Mg2+, and Fe2+. The enzyme showed a fibrinolytic activity of 22.53 U/mL at 40 °C and its contact with polyethylene glycol did not lead to any significant alteration of its secondary structure. This protein represents an important example of a novel fibrinolytic enzyme with potential use in the treatment of thromboembolic disorders such as strokes, pulmonary emboli, and deep vein thrombosis.

Purification of a fibrinolytic protease from Mucor subtilissimus UCP 1262 by aqueous two-phase systems (PEG/sulfate).

A fibrinolytic protease from M. subtilissimus UCP 1262 was recovered and partially purified by polyethylene glycol (PEG)/sodium sulfate aqueous two-phase systems (ATPS). The simultaneous influence of PEG molar mass, PEG concentration and sulfate concentration on the enzyme recovery was first investigated using a 2(3) full factorial design, and the Response Surface Methodology used to identify the optimum conditions for enzyme extraction by ATPS. Once the best PEG molar mass for the process had been selected (6000g/mol), a two-factor central composite rotary design was applied to better evaluate the effects of the other two independent variables. The fibrinolytic enzyme was shown to preferentially partition to the bottom phase with a partition coefficient (K) ranging from 0.2 to 0.7. The best results in terms of enzyme purification were obtained with the system formed by 30.0% (w/w) PEG 6000g/mol and 13.2% (w/w) sodium sulfate, which ensured a purification factor of 10.0, K of 0.2 and activity yield of 102.0%. SDS-PAGE and fibrin zymography showed that the purified protease has a molecular mass of 97kDa and an apparent isoelectric point of 5.4. When submitted to assays with different substrates and inhibitors, it showed selectivity for succinyl-l-ala-ala-pro-l-phenylalanine-p-nitroanilide and was almost completely inhibited by phenylmethylsulfonyl fluoride, behaving as a chymotrypsin-like protease. At the optimum temperature of 37°C, the enzyme residual activity was 94 and 68% of the initial one after 120 and 150min of incubation, respectively. This study demonstrated that M. subtilissimus protease has potent fibrinolytic activity compared with similar enzymes produced by solid-state fermentation, therefore it may be used as an agent for the prevention and therapy of thrombosis. Furthermore, it appears to have the advantages of low cost production and simple purification.

Integrated process production and extraction of the fibrinolytic protease from Bacillus sp. UFPEDA 485.

Fibrinolytic proteases are enzymes that degrade fibrin; these enzymes are a promising alternative for thrombolytic therapy, and microorganisms produce them. The aim of this study was to evaluate the optimum conditions for the integrated production and purification of fibrinolytic protease from Bacillus sp. UFPEDA 485. Extractive fermentation was carried out in a culture medium containing soybean flour and by adding polyethylene glycol (PEG) and Na2SO4 according to a 2(3) experimental design. In all assays, the enzyme preferentially partitioned to the bottom phase (K < 1), with an optimum activity of 835 U ml(-1) in the bottom phase (salt-rich phase). The best conditions for extractive fermentation were obtained with 18 % PEG 8000 and 13 % Na2SO4. Characterization showed that it is a metalloprotease, as a strong inhibition-residual activity of 3.13 %-occurred in the presence of ethylenediaminetetraacetic acid. It was also observed that enzymatic activity was stimulated in the presence of ions: CaCl2 (440 %), MgCl2 (440 %), FeSO4 (268 %), and KCl (268 %). The obtained results indicate that the use of a low-cost substrate and the integration of fermentation with an aqueous two-phase system extraction may be an interesting alternative for the production of fibrinolytic protease.