IMOBILISASI LIPASE PADA CHITOSAN BEAD DENGAN TEKNIK PENGIKATAN SILANG : PENGARUH pH DAN KONSENTRASI KITOSAN TERHADAP AKTIVITAS TRANSESTERASE

SUSAN PRIMADEVI, Dr. Tri Joko Raharjo, M.Si.

2013 | Tesis | S2 Ilmu Kimia

Telah dilakukan penelitian mengenai pengaruh pH dan konsentrasi kitosan pada proses imobilisasi lipase pada chitosan bead dengan teknik pengikatan silang. Penelitian ini bertujuan untuk mengetahui kondisi optimum proses imobilisasi. Kitosan dipreparasi dari cangkang kepiting dengan metode No dan Meyer (1989) kemudian dimodifikasi menjadi chitosan bead melalui proses swelling. Chitosan bead diikat silang dengan glutaraldehida. Imobilisasi lipase pada chitosan bead yang telah diikat silang dilakukan pada kondisi optimum seperti pH kelarutan enzim lipase dan konsentrasi kitosan. Enzim lipase terimobilisasi dan lipase bebas diuji aktivitas, stabilitas termal, stabilitas penggunaan ulang dan paramater kinetik melalui reaksi transesterifikasi minyak kelapa sawit dengan metanol. Kondisi optimum imobilisasi terjadi pada saat enzim lipase dilarutkan dalam bufer fosfat pH 6 dan konsentrasi kitosan 5%. Aktivitas transesterase enzim lipase terimobilisasi mengalami penurunan sebesar 20-40% sedangkan enzim lipase bebas sebesar 30-45% pada suhu pemanasan awal 35-45 oC. Penurunan aktivitas enzim lipase terimobilisasi dan lipase bebas terbesar terjadi pada suhu 45-50oC dengan penurunan sebesar 51,81% dan 97,29%. Enzim lipase terimobilisasi dan enzim lipase bebas mampu digunakan ulang sebanyak dua siklus reaksi dengan penurunan aktivitas sebesar 72,40% dan 56,29%. Afinitas enzim lipase terhadap substrat ditunjukkan dengan nilai KM. Nilai KM enzim lipase terimobilisasi dan enzim lipase bebas yaitu berturut-turut sebesar 0,800 dan 0,081. Lipase terimobilisasi mempunyai stabilitas termal yang lebih baik tetapi mempunyai stabilitas penggunaan ulang dan afinitas yang lebih rendah daripada enzim lipase bebas.

Effects of pH and chitosan concentration for immobilization lipase on chitosan bead by crosslinking technique has been carried out. The study was aimed to determine the optimum conditions for immobilization process. Chitosan was prepared from crab shell by No and Meyer methode (1989), then was modified into chitosan bead through swelled process. The beads were crosslinked using glutaraldehyde. Immobilization of lipase on the crosslinked chitosan beads was performed under the optimum conditions such as solubility pH of lipase and concentration of chitosan. Immobilized and free lipases were assayed its activity, thermal stability, repeated usage stability and kinetic parameters with transesterification reaction of palm oil using methanol. The optimum conditions of immobilization were achieved when lipase was dissolved in phosphate buffer at pH 6 and concentration of chitosan was 5%. Transesterase activity of the immobilized lipase decreased 20-40%, while activity of free lipase decreased 30-45% at the preheating temperature 35-45 °C. The largest decrease of immobilized lipase and free lipase activity occured at temperature of 45-50 oC with the value of decreasing were 51.81% and 97.29%. Immobilized and free lipases could be used for two reaction cycles with decreased activity of 72.40% and 56.29%. Affinity of enzyme on the substrate was shown by KM value. KM value of immobilized and free lipases were 0.800 and 0.081, respectively. Immobilized lipase has better thermal stability but has lower reuse stability and affinity than the free lipase.

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