Abstract Fibrinolytic proteases are a promising alternative in the pharmaceutical industry, they are used in the treatment of cardiovascular diseases, especially thrombosis. Microorganisms are the most interesting source of fibrinolytic proteases. The aim of this study was the production of fibrinolytic protease from Streptomyces parvulus DPUA 1573, the recovery of the protease by aqueous two-phase system and partial biochemical characterization of the enzyme. The aqueous two-phase system was performed according to a 24-full factorial design using polyethylene glycol molar mass, polyethylene glycol concentration, citrate concentration and pH as independent variables. It was analyzed the effect of different ions, surfactants, inhibitors, pH and temperature on enzyme activity. The best conditions for purifying the enzyme were 17.5% polyethylene glycol 8,000, 15% Phosphate and pH 8.0, it was obtained a partition coefficient of 7.33, a yield of 57.49% and a purification factor of 2.10-fold. There was an increase in enzyme activity in the presence of Fe2+ and a decrease in the presence of $\beta$-Mercaptoethanol, phenylmethylsulfonyl fluoride and Iodoacetic acid. The optimum pH was 7.0 and the optimum temperature was 40 ºC. The purified protease exhibited a molecular mass of 41 kDa. The fibrinolytic protease from Streptomyces parvulus proved to be a viable option for the development of a possible drug with fibrinolytic action.

RESUMO: A mastite causa significativas perdas econômicas à indústria leiteira bovina. O presente estudo teve como objetivo avaliar as propriedades antibacterianas de 39 derivados heterocíclicos (1,3-tiazóis e 4-tiazolidinonas) contra isolados clínicos de mastite em vacas leiteiras. Amostras de leite foram coletadas de vacas com mastite clínica e as espécies bacterianas isoladas foram identificadas por PCR. A atividade antibacteriana foi avaliada pelo método de microdiluição em caldo. Primeiramente, os 39 compostos heterocíclicos foram testados contra quatro isolados bacterianos (Staphylococcus aureus, Streptococcus agalactiae, Corynebacterium bovis e Escherichia coli) escolhidos aleatoriamente dentre os recuperados das amostras de leite (Estudo 1). Posteriormente, compostos com atividade antibacteriana mais forte foram testados contra todos os isolados bacterianos recuperados das amostras de leite (Estudo 2). Os compostos 1,3-tiazóis apresentaram a maior atividade antibacteriana, principalmente os compostos 30 e 38, que também apresentaram propriedades bactericidas de acordo com seus valores de concentração inibitória mínima (CIM) e concentração bactericida mínima (CBM). Os isolados Corynebacterium spp. e Enterobacteriaceae foram os mais suscetíveis aos compostos 30 e 38. Os compostos 30 e 38 mostraram-se promissores como novos agentes antimicrobianos.

ABSTRACT: Mastitis causes significant economic losses to the dairy cattle industry. The present study aimed to evaluate the antibacterial properties of 39 heterocyclic derivatives (1,3-thiazoles and 4-thiazolidinones) against clinical mastitis isolates from dairy cows. Milk samples were collected from cows with clinical mastitis and the bacterial species were identified by PCR. Antibacterial activity was assessed using the broth microdilution method. First, 39 heterocyclic compounds were tested against four bacterial isolates (Staphylococcus aureus, Streptococcus agalactiae, Corynebacterium bovis and Escherichia coli) randomly chosen from those recovered from the milk samples (Study 1). Subsequently, the compounds with the strongest antibacterial activity were tested against all the bacterial isolates recovered from the milk samples (Study 2). 1,3-thiazoles showed the strongest antibacterial activity, specially compounds 30 and 38, which also showed bactericidal properties according to their minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) values. Corynebacterium spp. and Enterobacteriaceae isolates were the most susceptible to compounds 30 and 38. Compounds 30 and 38 are promising targets for new antimicrobial agents.