Pemurnian Parsial dan Karakterisasi Urease dari Biji Kacang Panjang (Vigna unguiculata subsp sesquipedalis L.)

Abstract

<p>Urease merupakam enzim yang digunakan dalam hidrolisis urea menjadi amoniak dan asam bikarbonat dan telah banyak digunakan dalam proses industri. Tujuan penelitian adalah isolasi dan pemurnian urease dari kacang panjang serta karakterisasinya. Penelitian dimulai dengan melakukan perkecambahan biji kacang panjang selama 8 hari. Kecambah biji kacang panjang selanjutnya diekstraksi dengan menggunakan buffer fosfat pH 7 dan dipisahkan menggunakan sentrifugasi sehingga diperoleh ekstrak kasar urease. Ekstrak kasar urease selanjutnya difraksinasi menggunakan aseton pada tingkat konsentrasi 20, 40, 60 dan 80%. Fraksi yang mempunyai aktivitas spesifik paling tinggi selanjutnya dianalisis menggunakan metode SDS-PAGE untuk menentukan berat molekulnya dan dikarakterisasi lanjut meliputi: pengaruh suhu, pH, konsentrasi substrat dan penambahan ion logam terhadap aktivitas urease. Aktivitas urease ditentukan dengan metode Nessler. Hasil penelitian menunjukkan aktivitas spesifik urease dari kacang panjang paling tinggi ditemukan pada fraksi aseton (FA) 20. Hasil analisis berat molekul dengan metode SDS-PAGE diperoleh beberapa pita protein yang diduga berukuran sekitar 25 KDa dan 17 KDa. Kondisi optimum dari aktivitas urease diperoleh pada suhu 30 ºC, pH 7 dan konsentrasi urea 16,6 mM dengan nilai aktivitas 407,62 U/mL. EDTA dan ion logam dalam CaCl₂, NaCl, NiCl₂ dan CuCl₂pada variasi konsentrasi 10^-3, 10^-4 dan 10^-5M merupakan inhibitor urease FA 20 dari kacang panjang.</p><p><strong><span lang="EN-US">Partial Purification and Characterization of Urease from Asparagus Bean (<em>Vigna unguiculata subsp sesquipedalis </em>L<em>.</em>). </span></strong><span lang="EN-US">Urease is an enzyme used in urea hydrolysis to ammonia and bicarbonate acid and has been widely used in industrial processes. The study focused on isolation and purification of urease from asparagus beans and its characterization. The study was started with germination of asparagus beans for 8 days. Germinated asparagus beans were further extracted using phosphate buffer pH 7 and separated by centrifugation to obtain a crude extract of urease. The crude extract of urease was further fractionated using acetone at concentrations of 20, 40, 60 and 80%. The fraction with highest specific activity was then </span><span>analyzed using SDS-PAGE method to determine its molecule weight and characterized further including the influence of </span><span lang="EN-US">temperature, pH, substrate concentration, and metal ion addition to urease activity. The urease activity was determined by the Nessler̕ s method. The results showed that the specific activity of urease from asparagus beans was found with highest activity in fraction of acetone (FA) 20. Analytical result using SDS-PAGE method was obtained some protein bands having molecular weights about 25 KD and 17 KDa. The optimum conditions of urease activity was obtained at 30 °C, pH 7, incubation time 20 min and urea concentration 16.6 mM with activity value 407.62 U/mL. EDTA and </span><span>metal ions contained in </span><span lang="EN-US">CaCl₂, NaCl, NiCl₂ and CuCl₂ at concentrations of 10^-3, 10^-4 and 10^-5 M were FA 20 urease inhibitors.</span></p>