Pintip RuenwongsaBhinyo PanijpanPichit TosukhowongTamrongvit Chaijaroonporn2024-08-022024-08-02199019902024Thesis (M.Sc. (Biochemistry))--Mahidol University, 1990https://repository.li.mahidol.ac.th/handle/20.500.14594/100126Biochemistry (Mahidol University 1990)Bromoperoxidase was purified from Thai red seaweeds Polycarvernosa sp. by alcohol precipitation, alkaline precipitation, DEAE cellulose column chromatography and Sephadex G-100 column chromatography. Two types of bromoperoxidase, peak I and peak II, were obtained; they were different in several properties, including kinetic property. Peak I bromoperoxidase had a molecular weingt of 71,000 daltons whereas peak II enzyme had a molecular weingt of 45,000 daltons as determined by sephadex G-100 column chromatography. The isoelectric point of peak I and pesk II bromoperoxidase were 4.7 and 6.8 respectively. The optimum pH of peak I bromoperoxidase was 5.0 whereas that of peak II enzyme was 5.8 Peak I bromoperoxidase was stable in an acidic pH range from 5 to 9 whereas peak II enzyme was stable in an alkaline pH range from 7 to 12. The optimum temperature of peak I and peak II bromoperoxidase were 50 degree C and 55 degree C respectively. Peak I and peak II enzyme had similar thermal stability; 50% fo the activity was lost after incubation at 55 C for 30 min. The spectrum of peak I bromoperoxidase showed the Soret band at 403 nm, a characteristic of hemeprotein. However, the Soret band was not found in the spectrum of peak II enzyme indication that peak II bromoperoxidase was not a hemeprotein. Both peak I and peak II enzyme catalyzed the bromination of monochlorodimedone (MCD), phenol red and xylene cyanol FF. The km values for MCD, phenol red and xylene cyanol FF of peak I were 6.9 x 10(-6)M, 4.4 x 10(-6)M and 3.1 x 10(-6)M respectively. The Km values fro MCD, phenol red and xylene cyanol FF of peak II were 6.4 x 10(-5)M, 1.5 x 10(-5)M and 2.7 x 10(-5)M respectively. The km values for H(,2)O(,2) of peak II were in the range of 10(-5)M for all three organic substrates and the Km values for KBr of peak II enzyme were in the range of 10(-3)-10(-4)M. Activities of both peak I and kpeak II bromoperoxidase were inhibited by azide and cyanide, however peak I was more susceptible to azide inhibition than peak II enzyme. Effect of some effectors on activities of both peak I and peak II bromoperoxidase were also studiedxii, 108 leaves : ill.application/pdfengผลงานนี้เป็นลิขสิทธิ์ของมหาวิทยาลัยมหิดล ขอสงวนไว้สำหรับเพื่อการศึกษาเท่านั้น ต้องอ้างอิงแหล่งที่มา ห้ามดัดแปลงเนื้อหา และห้ามนำไปใช้เพื่อการค้าEnzymesSeaweedMaster ThesisMahidol University