TABLE 4.

Specific activities of CFEs of E. coli DH5α expressing L. helveticus CNRZ32 endopeptidases toward α_S1-CN (f1-9) and β-CN (f193-209)¹

Peptidaseb	Mean (SD) sp act towarda:
	αS1-CN (f1-9)	β-CN (f193-209)
Control	46 (19)‡	0.3 (0.2)§
PepE	ND	ND
PepE2	ND	ND
PepF	ND	14 (3.0)*
PepO	ND	ND
PepO2	3,700 (125)*	290 (19)†
PepO3	85 (21)†	88 (5.0)‡

^aSpecific 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.

^bCFEs 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).