Judul: Pemurnian dan pencirian protease dari isolat bakteri W-1 yang dihasilkan oleh tauco hitam
Abstrak: Enzim protease dari isolat bakteri W-1 yang diisolasi dari tauco hitam memiliki aktivitas fibrinolitik. Penelitian ini bertujuan memurnikan dan mencirikan protease dari isolat bakteri yang diisolasi dari tauco hitam yang merupakan salah satu makanan fermentasi tradisional Indonesia. Ekstrak enzim dimurnikan dengan presipitasi amonium sulfat kejenuhan 70%, dialisis (cut off 10 kD), dan kromatografi penukar ion DEAE Sepharose. Pemurnian menghasilkan satu fraksi enzim aktif. Aktivitas spesifik fraksi aktif adalah 3.860 U/mg dengan tingkat kemurnian 11.42 kali dibandingkan dengan ekstrak enzim kasar. Hasil analisis SDS-PAGE 15% memperlihatkan fraksi aktif protease terdiri atas 2 pita protein (29.7 dan 33.3 kD). Aktivitas optimum protease dicapai pada suhu 50oC dan pH 7. Uji zimogram 15% memperlihatkan bahwa protease mampu menghidrolisis substrat kasein dan fibrinogen dengan konsentrasi 0,01% (b/v). Aktivitas enzim protease menurun dengan adanya penambahan ion Na+, K+, Mg2+, Mn2+, dan Cu2+ (5 mM). Protease ekstrak kasar dihambat spesifik oleh inhibitor fenilmetilsulfonilklorida, N-p-tosil-L-lisin klorometilketon, dan soybean trypsine inhibitor sehingga digolongkan ke dalam kelompok protease serina.
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Judul: Pemilihan dan karakterisasi bakteri penghasil enzim proteolik dari terasi medan
Abstrak: Enzim protease yang diproduksi oleh isolat bakteri D1T2 diisolasi dari Terasi medan makanan fermentasi tradisonal Indonesia, menunjukkan aktivitas fibrinolitik. Penelitian bertujuan memperoleh isolat yang berpotensi memproduksi enzim protease dari isolat Terasi Medan dan mengkaji karakterisasi enzim tersebut. Ekstrak enzim protease dilakukan beberapa tahapan pemurnian dengan presipitasi ammonium sulfat 55%, dialisis menggunakan kantung dialisis (cut off 10 kD) dan pemekatan dengan polietilenglikol (PEG). Hasil penelitian menunjukkan bahwa aktivitas spesifik dialisat adalah 4.6461 U/mg dengan tingkat kemurnian 3.01 kali dibandingkan dengan ekstrak enzim kasar (1.5434 U/mg). Analisis SDS-PAGE 10% menunjukkan bahwa ekstrak kasar protease mempunyai 2 buah pita protein (34.70 kD dan 9.62 kD) dan dialisat dengan 1 buah pita (23.86 kD). Uji zimografi 10 % menunjukkan bahwa enzim protease ini mempunyai aktivitas kaseinolitik, fibrinolitik, dan gelatinolitik. Aktivitas protease meningkat dengan penambahan ion Ca2+ 1mM. Protease ini dihambat spesifik oleh TLCK (N-p-tosil-L-lisinklorometil keton), PMSF (Fenil Metil Sulfonil Fluorida), dan STI (Soybean Trypsin Inhibitor) sehingga digolongkan kedalam kelompok protease serin.
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Judul: The Effects of Variance of Interest rate to Variance of Annuity Future Values
Abstrak: Time value of money is a concept that refers to the difference of the value of money due to time difference. The value of money for present time would not be the same as the value of money in the future. The value of money for present time is called as Present Value (PV) of the money and the value of money for future time is called Future Value (FV) of the money. Determination the value of money, for present and future time, depends on the time and rate of return. The value of money is determined by several factors such as inflation, fluctuation of interest rates, and government policy in securities and taxation. Due to fluctuation of the value of money we need a FV formulation, it is useful for knowing whether an investment can be profitable or not, and this information is useful also in budget analysis. Annuity is defined as a series of payments made for a specific period. The payment, fixed or varied, can be made at the beginning or at the end of the period. Annuity paid at the beginning of the period is called annuity-due and annuity paid at the end of the period is called immediate annuity-certain. The accumulated value of the annuity after few years later is called as a final value or a future value. Burnecki et al. (2003) have discussed about the FV of a fixed-rate annuity in which payments are made according to the arithmetic or geometric series. They have also examined FV for annuities in which payments are made according to arithmetic or geometric series with random rates of interest. This paper examines FV for annuity-due in which payments are made according to arithmetic or geometric series with interest rates as a random variable, which is normal distribution ,  . Future value formula is expressed in recursive form. FV for annuity-due which payments are made according to the arithmetic or geometric series with random rates of interest is calculated by theoretical way and simulation way. The random rates of interest is denoted as k k i  i  , where k i an independent random variable; i is a constant and k  is a random variable which has normal distribution ,  . By using the determined parameters, a sequence of random rates of interest are generated for theoretical calculation. Meanwhile for the simulation, the random rates of interest is generated 1000 times for the simulation. The generated data give mean value, variance, and standard deviation. Moreover, error of mean value, variance, and standard deviation from the theoretical and simulation results are calculated. Error calculation uses Symmetric Mean Absolute Percentage Error (SMAPE). The smaller the value of SMAPE is the more accurate the simulation. The interest rate variances are varied from 0.000036 to 0.0001 to study the relationship between variance of rates of interest and variance of future value. The theoretical and simulation results show that when the variance of random rates of interest increases, then the variance of FV increases linearly. FV of the annuity-due in
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