Judul: Purification and Characterization of Extracellular Mananase Streptomyces purpurascens
Abstrak: Manan is the major component of plant hemicellulose is the second most abundant polysaccharide in nature. As a renewable subtance, there is abundance of hemicellulose in nature that can be degraded as useful end product. Mananase is a group of enzyme that has ability to hydrolyse hemicellulose into manan or polymer of manosa and manooligosaccharides. Streptomyces purpurascens produce extracelluler mananase that has unique characteristic; optimum temperature and pH is 50°C and 6.5 respectively. The purpose of this research was to purify and characterize the mananase Streptomyces purpurascens. Crude extract of mananase was precipitated with 70% acetone gradually, purified with ion exchange chromatography (DEAE cellulosa) and continue with gel filtration chromatography (Sephadex G-IOO). The molecular mass of the purified mananase after ion-exchange and gel filtration was estimated 95.072 kDa and 81.606 kDa. The optimum temperature and pH was 50°C and 6.5 respectively.
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Judul: Purifikasi Parsial dan Karakterisasi Enzim Mananase dari Bacillus pumilus
Abstrak: Bacillus pumilus isolate is one of bacterial collection from Biotechnology Culture Collection (BTCC) LIPI, isolated from Pari island waters was examined to determine the ability of bacteria to degrade mannan from Locust Bean Gum (LBG). Based on qualitative analysis, this isolate showed the abilities to degrade mannan while the quantitative analysis showed the highest mannanase activity was obtained on the third day of incubation time at 3,2 U/mL with 0,9 U/mg specific activity. Initial purification using ultrafiltration 5000 WMCO showed mannanase activity at 5,1 U/mL with 1,44 U/mg specific activity. Enzyme purification by gel filtration produced a peak in fraction no.31 with mannanase activity at 4,2 U/mL with 4,00 U/mg specific activity. Analysis of hydrolitic products by thin layer chromatography showed that the main products from Locust Bean Gum are manobiose, manotetraose and manohexaose. Maximum activity of the mannanase enzyme produced by B. pumilus isolate occurred at pH 5,0 and temperature of 40°C. This enzyme has 30,17 kDa single protein band when running with SDS PAGE with Michaelis Menten (Km) and maximum velocity (Vmax) at 0,076 mg/mL and 0,02 U/mg respectively.
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Judul: Integration of Islamic Stock Markets of OIC Countries Before and During the Russia-Ukraine War Crisis
Abstrak: Pasar saham yang terintegrasi memberikan dampak negatif seperti percepatan co-movement (pergerakan bersama) yang rentan terhadap guncangan ekonomi, maupun krisis pasar global ke pasar domestik. Salah satu krisis yang terjadi pada tahun 2022 adalah perang Rusia-Ukraina yang berdampak pada pasar saham, termasuk pada saham syariah yang dipercaya lebih tahan terhadap guncangan krisis global. Penelitian ini bertujuan untuk meneliti perkembangan, integrasi dan respon lima pasar saham syariah negara OKI pada perang Rusia-Ukraina. Metode yang digunakan adalah VAR/VECM pada indeks DJIMMT25, SPSADS, SPSUAEDS, JII, DJIMT, SPBMIR, dan SPBMIU. Hasil penelitian menunjukkan pergerakan yang sama pada pasar saham UAE dan Arab Saudi, sedangkan Turki mengalami tren positif selama perang. Pasar saham syariah negara OKI selama periode perang Rusia-Ukraina terkointegrasi, sementara pasar saham Malaysia memengaruhi pasar saham syariah empat negara OKI lainnya. Hasil IRF menunjukkan terdapat efek permanen pada volatilitas pasar saham syariah negara OKI akibat guncangan yang diberikan. Namun, respon volatilitas relatif kecil karena kontribusi guncangan lebih didominasi oleh pasar saham itu sendiri, An integrated stock market has negative impacts, such as accelerating co-movement, which is vulnerable to economic shocks and global market crises on the domestic market. One of the crises in 2022 was the Russia-Ukraine war which impacted the stock market, including Sharia stocks which were believed to be more resistant to the shocks of the global crisis. This study examines the development, integration, and response of OIC countries five Islamic stock markets in the Russia-Ukraine war. The method used is VAR/VECM on the DJIMMT25, SPSADS, SPSUUAEDS, JII, DJIMT, SPBMIR, and SPBMIU indices. The results show the same movement in the UAE and Saudi Arabia stock markets, while Turkey experienced a positive trend during the war. The Islamic stock market of the OIC countries during the Russia-Ukraine war was cointegrated. In contrast, the Malaysian stock market influenced the Islamic stock markets of the other four OIC countries. The IRF results show a permanent effect on the volatility of the Islamic stock market in OKI countries due to the shocks given. However, the volatility response is relatively small because the stock market itself dominates the contribution of shocks.
Keyword: co-movement, OIC, Rusia-Ukraine war, sharia stock market integration