| Study of protein which catalyzed formation of biosilica has opened up the opportunity to make the regular and specific silica structure in vitro. In this study, the silica protein was isolated from Marines sponge, Minsel 1 (Halichondria panacea), Minsel 2 (Halichondria sp) originated from Bunaken Island and Violet Sponge/SV (Haliclona sp) from Seribu Island. The protein was isolated through chemical extraction using hydrofluoric acid (HF 5%) and ammonium fluoride buffer (HF 2MINH4F 8M) and then analyzed with SDS-PAGE (12%). The estimated molecular weight of the protein were 43 kDafrom Minsel 1; 284 kDa and 38 kDa from Minsel 2; and 29 kDa dan 18 kDa from Violet Sponge. The silicatein like protein were able to catalyze formation of biosilica in vitro. The accumulation of TEOS for Minsel 1 was 90.24 nmol/ml, 545.24 mnol/ml for Minsel 2 and 190.59 nmol/rnl from SV when incubated at pH 6.8 for 24 hours. When the pH 4 was changed to pH 8 the TEOS accumulated with sample Minsel I dan Violet Sponge were similar. With Minsel 2 the TEOS accumulation was decreased down to 179.12 nmollml at pH acid (pH 4). |