activityThe protease activity was assayed by a modified caseinolyticPeterson’s method protocol [20] using Hammerstein casein (Merck,Darmstadt, Germany) as a substrate. Unless otherwise stated, asuitably diluted enzyme solution (0.5 ml) was mixed with 2.5 ml100 mM glycine-NaOH buffer supplemented with 3 mM CaCl2atpH 10 (Buffer A) containing 10 g/l casein, and incubated for 15 minat 70◦C. The reaction was stopped by adding 2.5 ml 20% TCA.The mixture was left at room temperature for 30 min, and theprecipitated proteins (non-digested) were removed by centrifu-gation at 10,000 × g for 20 min. After that, 0.5 ml of the clearsupernatant were mixed with 2.5 ml 500 mM Na2CO3and 0.5 mlFolin-Ciocalteu’s phenol reagent, followed by incubation at roomtemperature for 30 min. The absorbance of the resulting super-natant was measured at 660 nm against a blank control. One unitof caseinolytic activity was defined as the amount of enzyme thathydrolyzed the substrate and produced 1 g of amino acid equiva-lent to tyrosine per min under the assay conditions.The proteolytic activity present in the laundry detergent solu-tion was evaluated by the method of Jaouadi et al. [8] usingN,N-dimethylated casein as a substrate. One unit of protease activ-ity was defined as the amount of enzyme required to catalyze theliberation of 1 mol of product from N,N-dimethylated casein permin under the experimental conditions used.