The alkaline proteinase of Brevibacterium linens was partially purified through ultrafiltration and chromatography on Sephacryl S-200. The molecular weight of this enzyme was determined by gel electrophoresis in polyacrylamide to be 52 000 – 55 000. The proteinase hydrolyses natural polypeptides such as casein, haemoglobin, bovine serum albumin, and ovalbumin. An apparent Km for casein was determined to be 1.3 mg∙mL−1. The optimal pH for caseinolytic activity was between 7.0 and 8.5 at the optimal temperature of 45 °C. The isolated enzyme is thermolabile: incubation at 50 °C destroyed proteolytic activity. Substrate proteins have a stabilizing effect. Our inhibition studies revealed that the B. linens proteinase belongs to the serine proteinase class. Key words: Brevibacterium linens, proteinase, purification.
The influence of ozone on some properties of fruit jams was studied. Ozone did not influence the pH value, the contents of reducing sugars and organic acids, or the sensoric properties of the fruit jams tested. It may be used as a source of sterile air over the jam surfaces in yoghurt production.
Brevibacterium linens produces proteolytic enzymes in cultivation broth. One of them was purified by application of a two step procedure involving ultrafiltration and molecular sieving. The isolated enzyme hydrolyzed natural substrates: casein, hemoglobin, ovalbumin and bovine serum albumin with rations 22.2, 3.5, 1.6, 1.2 nkat mg-1, respectively. For casein the apparent Km 1.8 mg ml-1 was determined. The proteinase is fairly stable at pH 8.0 at 30 °C. Short term incubation at 50 °C denaturated the proteinase. SDS PAGE revealed an Mr of the proteolytic enzyme about 52 000 to 55 000.
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