Fifty plaque, soft canes and calculus samples were collected from teeth. Thirty samples were considered as true bacteria, about (10 bacteria/ml), on the surface of MS-agar {Mitis-Salivmus agar) medium. Sixteen isolates were considered related to genus Streptococcus varied between S.sanguis. S.mutans and S.milleri, depending on morphological and biochemical identification systems, these isolates were tested for the production of protease enzyme by measuring their clearance zone ratios on the surface of skin milk agar medium. All isolates were able to produce this enzyme. S.sanguis (N14) was chosen as the best one for production. Separation, and purification of S.sanguis (N14) proteoiytic enzyme was done by gradua precipitation with (0-30%) and (30-60%) saturated ammonium suifate, ion exchange chromatography on DEAE cellulose column then, the active fractions of partially purified protease were also further purified through gel filtration chromatography on sepharose 6B column. Purified protease gave an activity of (100 unit/ml), protein concentration of (1.8 mg/ml), specific activity of (555.5 unit/mg) with purification folds of (4.33) and a yield of (7.2%). Determination of S.sanguis (N14) purified protease molecular weight was elucidated by the use of gel filtration chromatcgraphy on sepharose 6B column with the presence of low olecular weight standard proteins, which determined as (56231 Separation of crude (S-lgA) from human colostrum was done using (50%) saturated ammonium sulfate. and purification of crude (S-lgA) was done using gel filtration on sepharose 4B column and ion exchange chromatography on DEAE cellulose column. The presence of (S-lgA) was tested usin immunodiffusion and conventional polyacrylamide gel eiectrophoresis techniques. Protein concentration for purified (S-lgA) by ion exchange chromatography on sepharose 6B column and gel filtration chromatography techniques was estimated as (2.2 mg/ml) and (1.5 g/mI respectively. Molecular weight of (S-lgA) was determined using gel filtration chromatography with the presence of high molecular weights standard proteins, and found to be (249000 dalton). Purified protease was tested for cleavage of purified (S-lgA) substrate by -gel filtration chromatography on sepharose 6B column. Purified protease was able to cleave (S-lgA) substrate into four fractions as compared with a control of purified (S-lgA), passed through the same column of gel filtration chromatography, which absent from these fractions. Through this study, the effect of different concentrations of inhibitors (EDTA, SDS and NaF) on the activity of purified protease was determined and found that, complete inhibition of protease activity was found with (0.05 M) EDTA, (0.015M) NaF and (2%) SDS. SDS. was considered, as the best inhibitor of proteolytic activity as compared with EDTA and NaF.