Judul: Pengaruh Garam pada Stabilitas Enzim Amiloglukosidase dari Aspergillus niger L 51/NRRL A-11, 264
Abstrak: Penelitian ini bertujuan untuk rnempelajari pengaruh jenis dan konsentrasi berbagai macam garam, pH dan suhu terhadap stabilitas enzim amiloglulrosidase dari kapang Aspergillus niger L51/Nrrl A-11, 264. Perlakuan yang diterapkan dalam penelitian i n i adalah penarnbahan CaC12 0 g/l, 0.5 g/l, "10 g/l dan 1.5 g/l; penambahai~ K2S04 0 11, 0.2 M, O.l+ Pf, 0.6 M; penambahan KC1 0 M, 0.2 M, 0.4 M dan 0,6 M. Perlakuan pengaruh pH terhadap stab i l i t a s l i ~ e l i p u t i pH 3,0, !t,O, ii ,5, 5,0, 6,O dan 7.0, sedangkan perlakuan pengaruh suhu terliadap s t a b i l i t a s meliputi suhu 60, 65, 70,dan 75'~. Pengamatan dilakukan terhadap a k t i f i t a s r e s i du, a ! r t i f i t z s awal dan khndungan protein enzim,
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Judul: Kestabilan Enzim Glukosa Oksidase Aspergillus niger Menggunakan Metode Constant pH Molecular Dynamic
Abstrak: Glukosa oksidase (GOD) dari Aspergillus niger (β-D-glukosa: oksigen 1- oksidoreduktase, EC 1.1.3.4, kode PDB : 1GAL) mengkatalisis oksidasi β-Dglukosa oleh molekul oksigen menjadi δ-gluconolactone, kemudian terhidrolisis secara spontan menjadi asam glukonat, dan hidrogen peroksida. Atas dasar kemampuan tersebut, GOD banyak digunakan dalam aplikasi bidang farmasi, di antaranya sebagai biosensor untuk penentuan kadar glukosa dalam darah. Parameter-parameter yang dapat mempengaruhi perubahan struktur dan fungsi protein dalam larutan adalah suhu, tekanan, dan pH. Pengaruh yang paling besar terhadap perubahan struktur dan fungsi protein tersebut adalah pH. Hal ini terjadi karena residu asam amino mengalami perubahan muatan akibat pengaruh protonasi dari larutan yang mempunyai pH rendah. Dinamika molekuler merupakan suatu metode simulasi dengan media komputer yang memungkinkan untuk merepresentasikan interaksi molekulmolekul atom dalam jangka waktu tertentu. Teknik ini berdasarkan pada persamaan hukum Newton dan hukum Mekanika. Simulasi dinamika molekul dapat mengetahui dinamika dan perubahan konformasi struktur protein pada tingkat atom. Selanjutnya, pemodelan lingkungan pH dalam simulasi ini dilakukan dengan cara memprotonasi residu asam amino yang bermuatan menggunakan metode simulasi Constant pH Molecular Dynamic (CPHMD). Tujuan dari penelitian ini adalah mencari dan menganalisis residu yang bertanggung jawab terhadap stabilitas konformasi enzim GOD Aspergillus niger akibat pengaruh dari pH. Selanjutnya untuk mencapai tujuan ini dilakukan analisis stabilitas konformasi enzim GOD tersebut dengan melakukan protonasi terhadap residu asam amino yang bermuatan pada pH 4, 5, 6 dan 7 dalam skala atomik. Analisis yang digunakan adalah analisis root mean square deviation (RMSD), struktur sekunder, root mean square fluctuation (RMSF), nilai derajat ionisasi asam amino (pKa) dan kurva protonasi. Berdasarkan analisis RMSD dan struktur sekunder, enzim 1GAL pada pH 4, 5, 6 dan 7 memiliki struktur yang masih stabil. Selain itu, berdasarkan data protonasi, Enzim 1GAL paling stabil pada pH 5, sedangkan residu penstabil enzim 1GAL pada simulasi pH 4, 5, 6 dan 7 adalah residu Glu82, Glu192, Asp206, Asp220, His270 dan His445.
Keyword: 1GAL, Constant pH Molecular Dynamic, Kestabilan enzim

Judul: Characteristic of Overshooting Top (OT) Based on  Himawari  8  Satellite  as  a  Convective  Cloud  Feature  that  Generates  Extreme Weather in the Java Island Region
Abstrak: Overshooting Top (OT) is a feature at the top of a convective cloud that is associated with extreme weather. Research on OT in tropical Indonesia is still very limited. The existence of geostationary satellites with wide area coverage and fast frequency observations is useful for observing the fast dynamics of the OT life cycle. Therefore, this study intends to analyze the relationship between OT and extreme weather, updraft and thermodynamic conditions of OT when extreme weather occurs, the best objective method for detecting OT in the day time and night time, and the spatiotemporal distribution of OT in the tropical region of Java Island during the 2018-2021 period. Based on visual analysis using visible channel and Himawari 8 sandwich products, 87% of extreme weather events in Java were accompanied by the appearance of OT. It indicates that the presence of the OT pattern is a convection cloud pattern or feature that is closely related to extreme weather events for the Java Island region. The existence of a time lag between the appearance of OT and extreme weather events on Java Island indicates that the OT of convection cloud can be used as a precursor or nowcasting for the appearance of extreme weather. Most of the convective cloud OT features during extreme weather events on Java Island have altitude that were only able to exceed the altitude of the equilibrium level and few were able to exceed the tropopause level of 9 km – 16 km. The difference in atmospheric conditions during extreme weather events on Java Island, which is in the tropics and subtropics, is a strong and unstable convective energy condition characterized by a larger CAPE, as well as unstable KI, LI, SI and TTI values. It is offset by kinematic factors in the form of a weak vertical wind shear (bulk wind shear 0-6 km) and a higher freezing point height. The difference between extreme weather events in the Java Island region and other tropical regions compared to subtropical regions is the strong updraft speed of convection clouds. The IRW Texture COMB algorithm based on the IRW-Texture Gradient modification and the COMB algorithm shows a significant increase in quality for detecting OT and non-OT pixels in Java. Rainy days with rainfall > 50 mm/day are very common in areas with an altitude of > 500 m. On the other hand, the level of convection activity which is indicated by the presence of OT and lightning is significantly reduced in this area. OT of convective clouds appear more frequently during the DJF season and less frequently during the JJA season. OT often appears during the day time and rarely at night time. Most OTs appear in the central part, away from the south and north coasts of Java Island during the day, while OTs that appear near the south and north coasts of Java Island can appear in the morning or afternoon.
Keyword: convective clouds, extreme weather, Overshooting Tops, Himawari 8 Satellite