Judul: Studi Penambatan Molekul Mutan Glukosa Oksidase IPBCC.08.610 untuk Meningkatkan Produksi Asam Glukonat
Abstrak: Glukosa oksidase (GOD) merupakan enzim oksidoreduktase yang mengkatalisis reaksi oksidasi glukosa menjadi β-D-glukono-1,5-lakton dan hidrogen peroksida. Kemudian, β-D-glukono-1,5-lakton akan terhidrolisis menjadi asam glukonat. Penerapan yang luas dari asam glukonat dalam berbagai industri menyebabkan meningkatnya permintaan produksi. Namun, konsentrasi glukosa yang lebih tinggi dari 40% (b/b) menghambat konversi glukosa menjadi asam glukonat karena penurunan konsentrasi kelarutan oksigen. Oleh karena itu, penurunan nilai Km diharapkan dapat menurunkan kejenuhan serta meningkatkan produksi asam glukonat. Penelitian ini bertujuan menganalisis interaksi antara mutan glukosa oksidase IPBCC.08.610 dengan β-D-Glukosa dalam meningkatkan produksi asam glukonat dengan menurunkan nilai Km. Mutasi dilakukan secara in silico dengan Chimera lalu dilakukan penambatan dengan AutoDockTools. Mutasi menyebabkan perbedaan pose ligan pada binding pocket, perbedaan konformasi -OH pada ligan, perbedaan indeks hidrofobisitas mutan T554M/D578P, serta penurunan nilai ΔG serta nilai Km pada mutan H559D, D578P serta T554M/D578P. Penurunan tersebut dapat meningkatkan kekuatan interaksi ligan-reseptor sehingga dapat meningkatkan produksi asam glukonat. H559D menjadi mutan terbaik yang dapat meningkatkan produksi tersebut berdasarkan nilai ΔG, nilai Km serta peningkatan kestabilan akibat penambahan ikatan hidrogen. Kata kunci: asam glukonat, glukosa oksidase, mutasi, penambatan molekul
Keyword: Glukosa Oksidase IPBCC.08.610, Asam glukonat, Penambatan molekul, Mutasi, Molecular Docking

Judul: Pemurnian dan Karakterisasi Glukosa Oksidase dari Isolat Aspergillus niger (IPBCC 08.610)
Abstrak: Glukosa oksidase (GOD) sedang banyak dikembangkan dalam berbagai aplikasi seperti pada industri makanan, obat-obatan, dan elektronik. Sumber GOD terbaik berasal dari Aspergillus niger karena diketahui memiliki aktivitas spesifik yang tinggi. Penelitian ini bertujuan untuk memurnikan glukosa oksidase dari A.niger (IPBCC 08.610) dengan menggunakan teknik kromatografi kolom gel filtrasi dan karakterisasinya. Pemurnian menggunakan kromatografi filtrasi gel menghasilkan satu fraksi enzim yang memiliki kadar protein lebih tinggi (Fraksi 4) dibandingkan fraksi lainnya. Aktivitas spesifik fraksi hasil kromatografi adalah 31.92 U/mg dengan tingkat kemurnian 8.86 kali dibandingkan dengan ekstrak enzim kasar yaitu 3.61 U/mg. Estimasi bobot molekul hasil analisis metode SDS-PAGE menunjukkan 2 pita protein yang berukuran 161 kDa dan 84 kDa. Adapun nilai Km dan Vmaks glukosa oksidase dengan substrat glukosa adalah 39 mM dan 3.7 x 10-3 mmol/det.
Keyword: Aspergillus niger, glukosa oksidase, Km, Vmaks, kromatografi kolom filtrasi gel, pemurnian, SDS-PAGE

Judul: Thermal Characteristics and Dynamics of Tropical Cyclone over Western North Pacific Ocean: A Case Study of Typhoon Songda (Chedeng) 2011
Abstrak: The frequent occasion of Tropical Cyclone (TC) over Western North Pacific (WNP) Ocean lies from 10˚N to 26˚N and 121˚E to 170˚E. Sources of TC development come from warm ocean temperature where latent heat is released during condensation processes and subsequently concentrated in the boundary layer. Relative humidity at 850-700 hPa is responsible to produce the most intense storm. Meanwhile, weak vertical wind shear between 850-200 hPa is one of the dynamical factors that lead to the development of TC. Pressure level of 850-200 hPa is chosen to minimize the thermodynamic effect in the lower troposphere. Typhoon Songda (Chedeng in the Philippines) or TSC lasted from May 18th to 30th, 2011 and strengthened into powerful Super Typhoon stage between May 24th and 27th. Long curving track and the exhibition of all sequences of TC life cycle, TSC is then considered as an ideal case of TC. The objective of the study with case of TSC is to investigate the role of thermal characteristics and dynamics on TC intensity. The research is carried out by using Advanced Research of Weather Research and Forecasting model (WRF ARW model) version 3.3. Two domains are employed in the model. The first domain situate from 02˚N to 40˚N and 118˚E to 149˚E and cover spatial resolution () of 33.1 km. The second domain situate from 09˚N to 27˚N and 119˚E to 132˚E with of 11 km. Timestep of the model () is 120 seconds. The model is supported by the following physical parameterization, i.e., Yonsei University Scheme (YSU) in the boundary layer, Kain-Fritsch scheme (KF) in the cumulus, and WRF Single-Moment 3-class scheme in the microphysics. Initial meteorological condition prior to the formation of the cyclone is generated using WRF ARW standard-release model. Sensitivity of the model output is obtained from a selected single-parameter change scenarios, namely, 10 % to 20 % decrease and increase of wind shear initial data at 850-200 hPa, and by 10 % to 20 % decrease of relative humidity initial data at 850-700 hPa. The result showed that the negative correlations between wind shear and intensity are found in wind shear scenarios. Wind shears of 10 ms-1 which lead to strengthening of the wind intensity in the early period of Typhoon development are found in wind shear scenarios. The effect of wind shear changes on wind intensity is statistically significant in the 20 % wind shear scenarios. During mature stage, weak wind intensity occurred when wind shear increase as given in the WRF standard-release and the 20 % decreasing scenario. Different situation is found in the 20 % increasing scenario where wind shear tend to weak and lead to strong wind intensity at this stage. Meanwhile, the reduction of moisture supply at 850-700 hPa resulting from 20 % decreasing relative humidity play a major role in the weakening of wind intensity and reduces mechanical energy of the cycle process as much as 300 J kg-1.
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