PURIFICATION AND CHARACTERIZATION OF A PROTEINASE FROM LACTOBACILLUS-PLANTARUM DPC2739

A proteinase from Lactobacillus plantarum DPC2739 was purified by a co mbination of ion exchange chromatography on DEAE-Sephacel and gel filt ration on Sephacryl-S-300 HR and TSK G3000SW. The enzyme had propertie s typical of an alkaline serine proteinase. It was optimally active at pH 9.5 and between 45 and 50 degrees C. The enzyme was monomeric with a molecular mass of similar to 42 kDa. It was strongly inhibited by p henylmethylsulphonyl fluoride, Cu2+ and Zn2+. The N-terminal amino aci d sequence showed no homology with known Lactococcus or Lactobacillus proteinases. The proteinase hydrolysed both alpha(s1)- and beta-casein s at approximately the same rate. (C) 1998 Elsevier Science Ltd. All r ights reserved.