TABLE 4.

Specific activities of CFEs of E. coli DH5α expressing L. helveticus CNRZ32 endopeptidases toward αS1-CN (f1-9) and β-CN (f193-209)1

PeptidasebMean (SD) sp act towarda:
αS1-CN (f1-9)β-CN (f193-209)
Control46 (19)0.3 (0.2)§
PepENDND
PepE2NDND
PepFND14 (3.0)*
PepONDND
PepO23,700 (125)*290 (19)
PepO385 (21)88 (5.0)
  • a Specific activity is measured in nmoles of substrate hydrolyzed per h per mg of protein. Values were corrected by subtracting the mean values obtained in the control treatments from CFE of E. coli DH5α (pJDC9). Means with different symbols are statistically different within a column at an α value of ≤0.05. Assays were performed under cheese-ripening conditions (pH 5.0 to 5.2, 4% NaCl, 10°C). ND, not detected.

  • b CFEs were prepared from E. coli DH5α(pJDC9) (control), E. coli DH5α(pSUW653) (PepE), E. coli DH5α(pSUW652) (PepE2), E. coli DH5α(pSUW651) (PepF), E. coli DH5α(pSUW51) (PepO), E. coli DH5α(pSUW29) (PepO2), or E. coli DH5α(pSUW650) (PepO3).