#TITLE_ALTERNATIVE#

• Main Author: TRIANA PAKPAHAN (NIM : 20911003)Pembimbing : Rukman Hertadi, D.Sc, MEIDY
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/18897
• Institution: Institut Teknologi Bandung

Halophilic proteins have thrived to maximize stability and activity at a high salt <br /> <br /> <br /> <br /> <br /> <br /> concentrations. Understanding the haloadaptation mechanism particularly the influence <br /> <br /> <br /> <br /> <br /> <br /> of salt on function, folding and solubility is important, for it has obvious <br /> <br /> <br /> <br /> <br /> <br /> potential application in the biotechnological industry. We explore the properties of <br /> <br /> <br /> <br /> <br /> <br /> halophilic proteins through their primary, secondary and tertiary structure analysis. <br /> <br /> <br /> <br /> <br /> <br /> At primary level, we compare the amino acid composition of halophilic and their <br /> <br /> <br /> <br /> <br /> <br /> homologous nonhalophilic. The compositions of helix, sheet and coil formation <br /> <br /> <br /> <br /> <br /> <br /> are assessed in the secondary structure analysis. We also calculate the composition <br /> <br /> <br /> <br /> <br /> <br /> of polar and non-polar residues, solvent accessible surface area, number of saltbridges <br /> <br /> <br /> <br /> <br /> <br /> and radius of gyration to give us more information insight from the protein <br /> <br /> <br /> <br /> <br /> <br /> properties from tertiary structure. In addition, we perform systematic comparison <br /> <br /> <br /> <br /> <br /> <br /> between mesophilic and halophilic proteins regarding the content of various types <br /> <br /> <br /> <br /> <br /> <br /> of amino acid clusters. A spectral graph theory is employed to detect such clusters <br /> <br /> <br /> <br /> <br /> <br /> in the protein. As a result, we found that halophilic proteins are characterized <br /> <br /> <br /> <br /> <br /> <br /> with the lower propensities of Cys, over representation of helix and beta sheets, <br /> <br /> <br /> <br /> <br /> <br /> and their electrostatic core surface is more accessible by the solvent than their hydrophobic <br /> <br /> <br /> <br /> <br /> <br /> core surface. From the amino acid clusters analysis, we found that in <br /> <br /> <br /> <br /> <br /> <br /> average, the number of clusters in mesophilic shows a larger value than halophilic <br /> <br /> <br /> <br /> <br /> <br /> proteins. Nevertheless, despite the number of clusters is less than in mesophilic, <br /> <br /> <br /> <br /> <br /> <br /> halophilic proteins show majority of hydrophobic residues forming cluster in their <br /> <br /> <br /> <br /> <br /> <br /> proteins and aromatic residues, in particular for the high overlap aromatic clusters. <br /> <br /> <br /> <br /> <br /> <br /> This indicates that hydrophobic and aromatic cores of halophilic proteins are more <br /> <br /> <br /> <br /> <br /> <br /> vigorous, particularly residues with high interaction, and hence, have role in haloadaptation.