Enkapsulasi enzim Dehidrogenase Laktat (DHL) dalam silika dengan bahan dasar Natrium SIlikat dari Abu Sekam Padi

HINDRYAWATI, Noor, Dr. Nuryono, MS

2005 | Tesis | S2 Ilmu Kimia

Telah dilakukan penelitian tentang enkapsulasi enzim Dehidrogenase Laktat (DHL) dalam silika melalui proses sol-gel dengan bahan dasar natrium silikat dari abu sekam padi. Beberapa parameter yang mempengaruhi aktivitas enzimatis dari hasil enkapsulasi juga dipelajari yaitu konsentrasi substrat L-laktat dan koenzim NAD+, pH, stabilitas termal dan kandungan ion natrium. Enkapsulasi dilakukan dengan mencampur larutan natrium silikat (NaSiO3) sol dan larutan bufer fosfat pH 7 yang berisi enzim DHL dan nikotinamida adenina dinukleotida (NAD+). Campuran digojok (shaker) selama 2-6 menit pada temperatur 4 °C kemudian dimasukkan dalam plat sumur mikro isi 96 dan dilakukan penuaan (aging) selama satu malam. Uji aktivitas enzimatis dari hasil enkapsulasi dilakukan dengan mengukur absorbansi NADH pada λ = 340 nm menggunakan instrument ELISA (Enzyme Linked Immunosorbent Assay) reader. Hasil uji aktivitas enzim terenkapsulasi dibandingkan dengan hasil uji aktivitas enzim bebas. Hasil penelitian menunjukkan bahwa enkapsulasi enzim DHL ke dalam silika tidak menurunkan aktivitas enzimatis secara signifikan. Stabilitas termal enzim DHL yang terenkapsulasi meningkat, walaupun setelah digunakan beberapa kali aktivitas enzimatis tinggal 30% dari aktivitas awal. Selain itu, aktivitas enzim DHL meningkat secara signifikan ketika koenzim NAD+ dan enzim DHL terenkapsulasi bersama. Adanya ion natrium dalam hasil enkapsulasi menurunkan aktivitas enzimatis enzim DHL secara signifikan.

In this research, Lactate dehydrogenase (LDH) enzyme was encapsulated in silica by sol-gel process using sodium silicate resulted from rice hull ash. Several parameters affecting the enzymatic activity of the encapsulated product were also studied; i.e. substrate and coenzyme concentration, medium acidity, thermal stability, and sodium content. The encapsulation was carried out by mixing sodium silicate (Na2SiO3) sol solution and phosphate buffer pH 7 containing both LDH enzyme and coenzyme of nicotinamide adenine dinucleotide (NAD+). After 2-6 minute of shaking, the mixture was then transferred into a 96-microwell plate and stored overnight. The encapsulation activity of encapsulation product was quantified by measuring absorption of NADH, as coenzyme hydrogenation product, at 340 nm utilizing an ELISA (Enzyme Linked Immunosorbent Assay) reader. For comparison similar experiment was also carried out for free enzyme. In the present study, it was observed that the encapsulation enzyme LDH in silica did not reduce the enzymatic activities significantly. The thermal stability of the encapsulated enzyme increased, eventhough it was used several times the activity of the enzyme still remained 30 % from the previous activity. Moreover, A significant improvement on the encapsulation activity of LDH was obtained when the NAD+ coenzyme and the LDH enzyme were encapsulated together. The presence of sodium in the encapsulation product, however, decreased the enzymatic activity of the LDH significantly.

Kata Kunci : Natrium Silikat, Abu Sekam Padi, DHL, enzyme encapsulation, lactate dehydrogenase, rice hull ash, sol-gel process.