%A 1217011060 Syathira Assegaf %T PENINGKATAN KESTABILAN ENZIM ?-AMILASE DARI Rhizopus oligosporus DENGAN PENAMBAHAN POLIETILEN GLIKOL ( PEG ) 6000 %X ABSTRACT ?-Amylase enzyme is an enzyme that has the activity of breaking down starch molecules and glycogen. This research was aimed to increase the stability of ?- amylase enzyme from Rhizopus oligosporus with the addition of Polyethylene glycol 6000. To achieve this goal, the production and isolation of enzymes, purification of enzymes were done, including the deposition of enzyme with ammonium sulphate (fractination), dialysis and characterization the enzyme before and after addition of Polyethylene glycol 6000. The results showed that the specific activity of crude extract of ?-amylase enzyme was 393.137 U/mg while the specific activity of fractionation purification enzyme was 890.35 U/mg and dialysis was 1861.89 U/mg. These results suggest that specific activity is increasing with enzyme purification. The purified enzyme have optimum pH 6.5 and optimum temperature is 55oC; KM = 24.0 mg mL-1 and Vmaks = 0.433 ?mol mL-1 min-1 substrat ; ki = 0.0099 min-1; t1/2 = 70 min and ?Gi = 104.35 kJ/mol. The enzyme of PEG 6000 addition of 4%, 6%, and 10% have optimum pH 6.5 and optimum temperature is 55oC, KM and Vmaks were shown with following data: KM = 22.96 mg mL-1 and Vmaks = 0.448 ?mol mL-1 min-1 substrat; ki = 0.0094 min-1; t1/2 = 73.7 min and ?Gi = 104.49 kJ/mol. For PEG 6000 6% KM = 17.46 mg mL-1 and Vmaks = 0.396 ?mol mL-1 min-1 substrat; ki = 0.0087 min-1; t1/2 = 79.6 min and ?Gi = 104.70 kJ/mol. For PEG 6000 10% KM = 15.91 mg mL-1 and Vmaks = 0.385 ?mol mL-1 min-1 substrat; ki = 0.0080 min-1; t1/2 = 86.6 min and ?Gi = 104.93 kJ/mol. The addition of PEG 6000 to the ?- amylase enzyme from Rhizopus oligosporus can increase the thermal stability based on decrease the ki value, the increase on t1/2 and ?Gi. ABSTRAK Enzim ?-amilase merupakan enzim yang mempunyai aktivitas memecah molekul pati dan glikogen. Penelitian ini bertujuan untuk meningkatkan kestabilan enzim ?-amilase dari Rhizopus oligosporus dengan penambahan Polietilen glikol 6000. Untuk mencapai tujuan tersebut, dilakukan produksi dan isolasi enzim, pemurnian enzim meliputi pengendapan enzim dengan amonium sulfat (fraksinasi) dan dialisis serta karakterisasi enzim sebelum dan sesudah penambahan Polietilen glikol 6000. Hasil penelitian menunjukkan bahwa aktivitas spesifik ekstrak kasar enzim ?- amilase sebesar 393,137 U/mg sedangkan aktivitas spesifik enzim hasil pemurnian fraksinasi sebesar 890,35 U/mg dan dialisis sebesar 1861,89 U/mg. Hasil ini menunjukkan bahwa aktivitas spesifik semakin meningkat dengan pemurnian enzim. Enzim hasil pemurnian mempunyai pH optimum yaitu 6,5 dan suhu optimum 55oC; KM = 24,0 mg mL-1 danVmaks = 0,433 ?mol mL-1 menit-1 substrat ; ki = 0,0099 menit-1; t1/2 = 70 menit dan ?Gi = 104,35 kJ/mol. Enzim hasil penambahan PEG 6000 4%, 6%, dan 10% mempunyai pH optimum yaitu 6,5 dan suhu optimum 55oC nilai KM dan Vmaks berturut-turut yaitu KM = 22,96 mg mL-1 danVmaks = 0,448 ?mol mL-1 menit-1 substrat; ki = 0,0094 menit-1; t1/2 = 73,7 menit dan ?Gi = 104,49 kJ/mol. Untuk PEG 6000 6% KM = 17,46 mg mL-1 danVmaks = 0,396 ?mol mL-1 menit-1 substrat; ki = 0,0087 menit-1; t1/2 = 79,6 menit dan ?Gi = 104,70 kJ/mol. Untuk PEG 6000 10% KM = 15,91 mg mL-1 danVmaks = 0,385 ?mol mL-1 menit-1 substrat; ki = 0,0080 menit-1; t1/2 = 86,6 menit dan ?Gi = 104,93 kJ/mol. Penambahan PEG 6000 pada enzim ?-amilase dari Rhizopus oligosporus dapat meningkatkan stabilitas termal yang dapat dilihat dari penurunan nilai ki, peningkatan waktu paruh dan ?Gi. %C UNIVERSITAS LAMPUNG %D 2017 %I FAKULTAS MATEMATIKA DAN ILMU PENGETAHUAN ALAM %L eprints29151