## 3 Results and Discussion
### Evaluation of the Ability of Protease to Resist Stain Redeposition  
The reaction solution was analyzed by SDS-PAGE (Figure 4), the molecular weight of alkaline protease was approximately 30 kDa, and the molecular weight of keratinase was approximately less than 15 kDa. After the reaction of protein stain and alkaline protease, the molecular weight of the protein was concentrated in 50-80 kDa, and a small part of the molecular weight was concentrated in 25-30 kDa. After the protein stain liquid was hydrolyzed by keratinase, only a small amount of protein had a molecular weight of 30 kDa. This result indicates that the protein-decomposing effect of keratinase is significantly better than that of alkaline protease. The 4 U enzyme activity of trypsin was reacted with the protein stain solution. The molecular weight of the protein after the reaction was less than 25-35 kDa. The amount of trypsin added was much smaller than those of alkaline protease and keratinase, but the protein stains were decomposed effectively. A comparison \begin{table}
\begin{tabular}{c c c} \hline \hline \multirow{2}{*}{**Washing Performance**} & \multicolumn{2}{c}{**Reflectivity (\%)**} \\ \cline{2-3}  & **Protein-Fouling Cloth** & **Blood-Dirty Cloth** \\ \hline Before washing & 13.23 \(\pm\) 1.12 & 10.33 \(\pm\) 1.0 \\ Basal detergent & 20.90 \(\pm\) 0.56 & 26.20 \(\pm\) 1.76 \\ Alkaline protease & 25.60 \(\pm\) 0.59 & 25.20 \(\pm\) 1.39 \\ Keratinase & 29.38 \(\pm\) 0.79 & 29.58 \(\pm\) 2.50 \\ Trypin & 32.90 \(\pm\) 1.90 & 41.08 \(\pm\) 0.60 \\ Weak alkaline protease & 21.95 \(\pm\) 0.75 & 18.43 \(\pm\) 1.72 \\ Neutral protease & 19.10 \(\pm\) 0.91 & 21.45 \(\pm\) 2.10 \\ Acid protease & 20.85 \(\pm\) 0.96 & 22.48 \(\pm\) 2.12 \\ Aminopeptidase & 20.83 \(\pm\) 0.51 & 19.93 \(\pm\) 1.98 \\ Flavour protease & 23.90 \(\pm\) 1.53 & 30.40 \(\pm\) 0.71 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Washing performance of protease on protein-fouling and blood-dirty cloths. of the SDS-PAGE results with the application results showed that the protease with a better washing effect could break down protein stains from large molecules into small molecules, and the stains were easier to remove under the action of detergents. Figure 1: Surface image of protein-fouling cloth. (**a**) Unwashed protein-fouling cloth (\(500\times\)). (**b**) Protein-fouling cloth after washing with alkaline protease (\(500\times\)). (**c**) Protein-fouling cloth after washing with keratinase (\(500\times\)). (**d**) Protein-fouling cloth after washing with trypsin (\(500\times\)). Surface image of blood-dirty cloth (**e**) Unwashed blood-dirty cloth (\(500\times\)). (**f**) Blood-dirty cloth after washing with alkaline protease (\(500\times\)). (**g**) Blood-dirty cloth after washing with keratinase (\(500\times\)). (**h**) Blood-dirty cloth after washing with trypsin (\(500\times\)). SEM images of protein-fouling cloth before and after washing. (**i**) Unwashed protein-fouling cloth (\(420\times\)). (**j**) Protein-fouling cloth after washing with alkaline protease (\(420\times\)). (**k**) Protein-fouling cloth after washing with keratinase (\(420\times\)). (**l**) Protein-fouling cloth after washing with trypsin (\(420\times\)). (**m**) Blood-dirty cloth after washing with keratinase (\(440\times\)). (**n**) Blood-dirty cloth after washing with trypsin (\(410\times\)). The bloodstains on the surface of the cloth treated with alkaline protease, keratinase, and trypsin were compared (Figure 5). Protein molecular weights after treatment with alkaline protease were 70 and 25 kDa. Bloodstains were deposited on the surface of the  
Figure 4: SDS-PAGE result graph. (**A**) M is Marker. (i) Protein stain and alkaline protease. (ii) Alkaline protease and double-distilled water. (iii) Protein stain and keratinase. (iv) Keratinase and double-distilled water. (v) Protein stain and alkaline protease and keratinase. (vi) Alkaline protease and keratinase and double-distilled water. (vii) Protein stain and trypsin. (viii) Trypsin and double-distilled water. (**B**) M is Marker.