Enzyme-dextran conjugates

Enzymes are widely used in medicine, many fields of biotechnology and industry. In these fields, enzymes being stable against high temperature, pH and other media conditions are desired. Conjugates of natural and synthetic macromolecules with enzymes provides wide usage in medicine and in many fields of biotechnology. In this study, Horseradish Peroxidase-Dextran and Glucose Oxidase-Dextran covalent conjugates were synthesized whose resistance was increased against high temperature and extreme pH?s. The obtained conjugates were examined with GPC system and FTIR spectroscopy. Activities of synthesized conjugates and purified enzymes at pH:7 is determined after keeping them for 0, 15, 30 ve 60 minutes in different temparatured waterbaths. In all keeping periods, a slight decline in the activities of HRP-Dextran conjugates against increasing temperatures is observed when it is compared to purified enzyme. Especially the conjugate with 1/10 molar ratio displayed quite well stability against high temperatures. Analogous condition is valid for GOD/Dextran conjugates and especially the conjugate with 1/5 molar ratio showed greater activity compared to purified enzyme. Activities of HRPDextran conjugate with 1/10 molar ratio and GOD-Dextran conjugate with 1/5 molar ratio at different pHs and temperatures were determined. The activities of pure HRP and GOD were changed sharply depending on pH, whereas their conjugates were more stable. In higher temperatures (70oC) and in pH values in which pure enzyme lost its activity, it is seen that GOD-Dextran conjugate with 1/5 molar ratio showed activity. Storage stability of HRPDextran( nHRP/nD=1/10; Mw 75.000) and GOD-Dextran(nGOD/nD:1/5; Mw:75.000 and nGOD/nD:1/1; Mw:188.000) conjugates at room temperature and 4 oC were also studied and showed better stability than purchased and pure enzymes. Keywords: ?Horseradish? peroxidase (Armoracia rusticana), glucose oxidase, dextran aldehyde, conA, HRP-dextran conjugates, GOD-dextran conjugates, activity, storage stability, GPC, FTIR.