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Samuel Lihan
Department of Molecular Microbiology, Faculty of Resource Science and Technology, Universiti Malaysia Sarawak, 94300 Kota Samarahan, Sarawak, Malaysia
Biochemistry, Genetics & Molecular Biology Immunology & microbiology Medicine & Pharmacology

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Journal : Microbiology Indonesia

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Molecular Dynamics Analysis of Thermostable DNA Pol I ITB-1 CHANGI WONG; PETER PROKSCH; LEE TUNG TAN; SAMUEL LIHAN; AAZANI MUJAHID; MORITZ MÜLLER
Microbiology Indonesia Vol. 1 No. 3 (2007): December 2007
Publisher : Indonesian Society for microbiology

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5454/mi.1.3.1

Abstract

One of the thermostable enzymes, which has been widely used in the biotechnological research, is DNA polymerase. The coding sequence of local DNA Pol I gene from a local thermophilic bacterium, namely DNA Pol I ITB-1, has been cloned, sequenced, and overexpressed. However, study on thermostability of this enzyme is very limited. In the present study, thermostability of the protein was evaluated by thermal unfolding simulation at 300, 400, and 500 K. Our simulation revealed that the secondary and tertiary structures of the protein was not significantly affected by thermal perturbation at 300 K, but they were affected and even gradually unfolded by that perturbation at 400 and 500 K. Evaluation of the root mean square fluctuation (RMSF) of individual residues from the simulation at 400 and 500 K revealed the distribution of the thermostability regions in the protein structure. From the RMSF analysis at 400 K, we found that thermostability of the 3’-5’ exonuclease domain was lower compared to that of the other domains. Where as from the RMSF analysis at 500 K, we found that in each domain of DNA pol I ITB-1 there was a single extraordinary thermostable a-helix which was likely to be the core of each corresponding domain. Thus our simulation provides a thermostability map of DNA Pol I ITB-1. Such information will be very valuable for the next genetic engineering work in determining a mutation target to modify thermostability of this enzyme.
Isolation, Identification and Screening of Antimicrobial Properties of the Marine-Derived Endophytic Fungi from Marine Brown Seaweed CHANGI WONG; PETER PROKSCH; LEE TUNG TAN; SAMUEL LIHAN; AAZANI MUJAHID; MORITZ MÃœLLER
Microbiology Indonesia Vol. 9 No. 4 (2015): December 2015
Publisher : Indonesian Society for microbiology

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (553.03 KB) | DOI: 10.5454/mi.9.4.1

Abstract

Marine seaweeds are known to produce valuable medicinal compounds such as antioxidants and anticoagulants, and have been reported to display antimicrobial activity against gram positive and gram negative bacteria. Several studies have identified so-called endophytic fungi living inside their hosts as the source of active compounds. In this study marine brown seaweed, Padina sp., was studied with regards to their endophytic fungi to assess if they are the source of the reported antimicrobial activity. Twenty fungal isolates were isolated from Padina sp. collected off Talang-Talang Island, Sarawak, Malaysia. All isolates were screened for their antimicrobial properties and 11 out of 20 isolates displayed positive results. DNA was successfully extracted for five isolates and sequence analysis grouped all of them with other endophytic fungi. “Fungus 2” seems to be related to a so far uncultured endophytic fungus. “Fungus 19” showed the most promising antimicrobial properties and was chosen for further agar well assay and cytotoxicity testing. Its ethyl-acetate extract showed positive results in the agar well assay and also a cytotoxic effect on Artemia nauplii. The extract was screened using HPLC and showed a compound similar to a known anti-cancer compound, dihydromyricetin, which is also an anti-intoxicant, anti-inflammatory and anti-oxidative agent which may be responsible for the observed antimicrobial activity.
Co-Authors AAZANI MUJAHID CHANGI WONG LEE TUNG TAN MORITZ MÃœLLER MORITZ MÜLLER PETER PROKSCH