Cell-wall-associated proteinase of Lactobacillus delbrueckii subsp. bulgaricus CNRZ 397: differential extraction, purification and properties of the enzyme

Appl Microbiol Biotechnol. 1991 Nov;36(2):196-204. doi: 10.1007/BF00164419.

Abstract

Whole cells of Lactobacillus delbrueckii subsp. bulgaricus CNRZ 397 were able to hydrolyse alpha- and beta-caseins. Irrespective of the growth medium used, milk or De Man-Rogosa-Sharpe (MRS) broth, identical patterns of alpha- and beta-casein hydrolytic products, respectively, were visualized by sodium dodecyl sulphate-polyacrylamide gel electrophoresis. A soluble proteinase present in cell-wall extracts was active on caseins and displayed the same hydrolytic patterns as whole cells. It was purified from cell-wall extract to homogeneity by ultrafiltration and ion exchange chromatography. The enzyme is a monomer with a molecular mass of 170 kDa, an optimum temperature of 42 degrees C and an optimum pH of 5.5. It was strongly activated by dithiothreitol and partially inhibited by E-64. These properties indicate that cysteine residues play an important role in the enzyme mechanism. The purified proteinase was not able to hydrolyse di- or tripeptides.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Amino Acids
  • Bacterial Proteins / isolation & purification*
  • Bacterial Proteins / metabolism
  • Caseins / metabolism
  • Cell Wall / enzymology*
  • Chromogenic Compounds / metabolism
  • Endopeptidases / isolation & purification*
  • Endopeptidases / metabolism
  • Hydrolysis
  • Lactobacillus / enzymology*
  • Molecular Sequence Data
  • Substrate Specificity

Substances

  • Amino Acids
  • Bacterial Proteins
  • Caseins
  • Chromogenic Compounds
  • Endopeptidases