Judul: Isolasi dan Karakterisasi Gen pol Simian Retrovirus (SRV) asal Macaca fascicularis dan Macaca nemestrina Isolat Indonesia.
Abstrak: Jumlah penderita HIV AIDS di Indonesia meningkat dari tahun ke tahun. Penelitian pengembangan obat antiviral mutlak diperlukan. Untuk itu, perlu dikembangkan model virus yang memiliki karakteristik mirip dengan HIV mengingat penggunaan virus HIV sebagai virus model memiliki resiko keamanan yang lebih tinggi. Penelitian ini merupakan langkah awal untuk pengembangan virus model HIV dari Simian retrovirus (SRV) isolat Indonesia berdasarkan karakter-karakter spesifiknya. Tujuan penelitian ini adalah melakukan isolasi dan identifikasi gen pol Simian Retrovirus (SRV) isolat Indonesia asal Macaca fascicularis dan Macaca nemestrina yang selanjutnya dapat dikarakterisasi urutan nukleotidanya, dianalisis kekerabatannya, urutan asam aminonya, conserve domainnya, dan pemodelan struktur tiga dimensinya menggunakan analisis bioinformatika. Isolasi dilakukan dengan teknik PCR menggunakan sepasang primer 3284U dan 4925L. Amplifikasi gen pol dengan teknik PCR menghasilkan pita spesifik yang masing-masing berukuran sekitar 1600 bp. Hasil analisis sekuens DNA menunjukkan bahwa virus yang terdapat di dalam sampel Macaca fascicularis adalah SRV 2 sedangkan virus yang terdapat di dalam sampel Macaca nemestrina adalah Simian endogenous retrovirus. Oleh karena itu, virus SRV asal Macaca nemestrina tidak bisa dilakukan pemodelan struktur tiga dimensinya. Hasil isolasi dan permodelan struktur protein gen penyandi reverse transkriptase dan RNase-H SRV 2 asal Macaca fascicularis Indonesia telah berhasil dilakukan. Sisi aktif dari kedua enzim tersebut juga telah berhasil diidentifikasi dan ditentukan urutan asam aminonya. Sisi aktif dari RNase-H terdiri atas tiga asam amino dan reverse transkriptase terdiri atas 27 asam amino. Hubungan kekerabatan enzim dari SRV-2 isolat Indonesia menunjukkan bahwa enzim reverse transkriptase dan RNase-H isolat Indonesia dapat digunakan sebagai model untuk mempelajari enzim dari retrovirus lainnya.
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Judul: Pengembangan enzim rekombinan reverse transcriptase simian betaretrovirus serotipe-2 isolat indonesia asal monyet ekor panjang
Abstrak: Reverse transcriptase (RT) is a multifunctional enzyme that catalyzes the formation of double-stranded DNA from single-stranded RNA viral genomes. Reverse transcription is an essential and critical step in life cycle of all retroviruses replication. RT has become an important enzyme in molecular biology, genetics and medicine for the synthesis of complementary DNA (cDNA) from messenger RNA (mRNA). The application of this enzyme combining with PCR amplification technique (RT-PCR) has expanded our knowledge of numerous cellular regulatory mechanisms and has become a gold standard to facilitate the coding region cloning of any gene of interest. The development of biotechnology has been relying on the availability of this efficient RT. In biomedical fields, RT of human immunodeficiency virus (HIV), the virus causing acquired immunodeficiency syndrome (AIDS) has been the most studied enzyme due to the prime target for the development of antiretroviral drug therapy of HIV/AIDS. Simian betaretrovirus serotype-2 (SRV-2) is the causative agent of simian acquired immunodeficiency syndrome (SAIDS) in Asian macaques with varying severity. While SRV is an important pathogen in Asian macaque and causes a potential confounding variable in biomedical research, SRV also provides a valuable viral model to compare with other retrovirals for a better understanding of aspects of retroviral–host interactions, infection mechanism, retroviral structure, antiretroviral and vaccine development. As is characteristic of all retroviruses, SRV-2 can transcribe its own RNA genome into a double-stranded DNA by the action of reverse transcriptase enzyme. The presence of gene encoding RT enzyme in SRV-2 genome potentially be studied and utilized further as RT enzyme model for developing the anti RT drug of others retrovirus. On the other hands, the gene encoding SRV-2 RT can be isolated and cloned to produce RT recombinant enzyme and applied in molecular biology techniques. In this study, we isolated the gene encoding RT enzyme of SRV-2 that infected Indonesian cynomolgus monkey and predicted the three dimensional (3D) structure model using I-TASSER (Iterative Threading ASSEmbly Refinement) computational program and visualized with PyMol program. Gene expression was constructed in Escherichia coli expression system with Gateway technology methods using pENTR/SD/TOPO entry vector and pDEST17 destination vector. Purification was performed using Ni2+-NTA affinity chromatography. Expression was analyzed using SDS-PAGE and Western blot techniques; meanwhile enzyme activity was measured using RT colorimetric assay and RT-PCR technique. We isolated the gene encoding RT enzyme of SRV-2 Indonesian isolate at nucleotide position 3284-4925 consisted of 547 amino acids. The I-TASSER program has predicted the three dimensional structure model of RT SRV-2 enzyme that consisted of palm/finger, thumb, connection and RNase H domain. The polymerase active site located in the finger/palm subdomain characterized by three conserved catalytic aspartates (Asp90, Asp165, Asp166), and has a highly conserved YMDD motif as Tyr163, Met164, Asp165, and Asp166. This SRV-2 RT structure model has the highest homology to HIV-1 RT (2B6A.pdb). Meanwhile, the structure of SRV-2 RNase H closely related to its ortologs such as Escherichia coli RNase H (1GOA) and HIV-1 RNase H (3QIO, 3HYF). The catalytic active site of SRV-2 RNase H contains three amino acid carboxylateresidues as Asp436, Glu465 and Asp486. Analysis of expression using SDS
Keyword: reverse transcriptase, recombinant enzyme, SRV-2 RT,, Escherichia coli expression system, I-TASSER

Judul: Hydroxyapatite-Chitosan Composite Coating on Stainless Steel 316 to Improve Corrosion Resistance
Abstrak: Metals that were used in bone implantation should have good corrosion resistance that were not easily corroded when implanted into the body. Metal corrosion resistance of stainless steel 316 can be enhanced through the metal coating by hydroxyapatite-chitosan composite with composition ratio of hydroxyapatite (gram) and chitosan 3% (mL) 0.2:0, 0.2:0.1, 0.2:0.5, 0.2:1.0, and 0.2:1.5. Besides improving the corrosion resistance of metal, the presence of chitosan also maintain the position of hydroxyapatite on metal surfaces. Corrosion resistance increases with increasing amount of chitosan added and the best composition of hydroxyapatite-chitosan composite was 0.2:1.0.
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