Judul: Uricase activity and kinetics of various cells of Lactobacillus plantarum
Abstrak: Uric acid concentration could be determined by spectrophotometry method. Uric acid was oxidized into allatonin in the presence of uricase and calculated by measuring the decrease of uric acid absorbance at 293 nm. These uricase were obtained from cells of Lactobacillus plantarum. L. plantarum K. Mar. E was isolated from passion fruit skin and L. plantarum Mgs. Psmb and Mgs. Bst from mangosteen. This research was conducted to observe the activity and kinetics of uricase from various cells of L. plantarum by spectrophotometric method. The plate assay method indicated that L. plantarum produced uricase, based on the clear zone about 0,2 mm on glucose yeast peptone medium contained 0,2% uric acid. The optimum condition of uricase activity from the three different sources occured in physiological condition. Uricase activity generated from cells of L. plantarum K. Mar. E, Mgs. Psmb, and Mgs. Bst were 0,1073; 0,0867; and 0,0842 U/mL, respectively. The kinetic parameters for uricase, determined with uric acid as the substrate. Vmax produced by L. plantarum K. Mar. E, Mgs. Psmb, and Mgs. Bst were 1,3635; 0,0316; and 0,0418 U/mL of bacterial culture, respectively and KM 0,1541; 0,0061; and 0,0054 mM, respectively. Uricase activity in various bacterial cells of L. plantarum was stable until the second day.
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Judul: Penentuan kinetika urikase dari sel Bacillus subtilis, B. megaterium, dan B. cereus
Abstrak: Uric acid concentration could be determined based on the oxidation of uric acid into alantoin with the presence of uricase. Determination is needed to diagnose the occurrence of kidney disease in gout patients. This research used uricase cells derived from Bacillus subtilis, B. megaterium, and B. cereus to study their kinetics using spectrophotometry method to measures the decrease of uric acid absorbance at 293 nm. The optimum conditions of uricase activity from the three bacterial cells occured in physiological conditions and uricase activity was stable until the second day. The values of maximum velocity (Vmax) for B. subtilis, B. megaterium, and B. cereus were 0.0853, 0.0824, and 0.0412 mM/min, respectively. The values of Michaelis-Menten constant (Km) for B. subtilis, B. megaterium and B. cereus were 0.0029, 0.0036, and 0.0036 mM, respectively. The value of catalytic constant (kkat) for B. subtilis, B. megaterium, and B. cereus were 266.4109, 171.6797, and 257.6257 mM/min mL OD=1, respectively. Based on these results that the most powerful bacteria bind the substrate was B. subtilis with the least Km value, and the highest Vmax and kkat.
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Judul: Klasifikasi Imbalanced data menggunakan algoritma klasifikasi voting feature intervals
Abstrak: Imbalanced data atau data yang tak berimbang merupakan suatu kondisi dimana pada sebuah himpunan data terdapat satu kelas yang memiliki jumlah instance yang kecil bila dibandingkan dengan kelas lainnya. Contohya pada suatu himpunan data yang terdiri dari dua kelas dimana rasio jumlah instance antara kedua kelas sebesar 1 : 100, 1 : 1000, dan 1 : 10.000. Kondisi imbalanced data dapat menyebabkan pengklasifikasian data yang tidak optimal (Barandela et al. 2002).
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