KAJIAN AWAL HUBUNGAN STRUKTUR-FUNGSI CU/ZN SUPEROKSIDA DISMUTASE CITRUS LIMON

• Main Author: Husen Kartadinata, Lydia
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/48740
• Institution: Institut Teknologi Bandung

Superoxide dismutase from Citrus limon (SOD_Cl) is a metalloprotein with Cu and Zn as its metal cofactor (Cu/ZnSOD). The activity of SOD_Cl as a stable antioxidant protein at acidic pH and under the activity of protease chymotrypsin and trypsin has made it a candidate for oral and topical therapeutic protein. Three-dimensional structure of SOD_Cl is needed to study its structure and mechanism as an acid-resistant protein. This study aims to analyse the activity and characterize the molecule of SOD_Cl, and to acknowledge the characteristics of SOD_Cl based on in silico and bioinformatics study of its structure. SOD_Cl overproduction was done by protein expression in Escherichia coli BL21(DE3). Addition of a polyhistidine fragment at the amino terminus of SOD_Cl allows purification using Ni2+ -NTA affinity column chromatography. The characterization of SOD_Cl using zymography showed that its activity in LEW containing imidazole is lower than in Tris-HCl and LEW. The molecule’s dimension of SOD_Cl in phosphate buffer with the pH of 6, 7, and 8 analysed using dynamic light scattering (DLS) shows a trend of protein aggregation due to high molecule dimension. The modelling of SOD_Cl structure was done using Swiss-Model based on the template structure with highest identity 83,55% given by Cu/ZnSOD Potentilla atrosanguinea (PDB ID: 2q2l). The model of SOD_Cl gives GMQE value of 0,95 and QMEAN value of 0,11, indicating usage of the right template. Validation using MolProbity shows the model of SOD_Cl can be used. Based on the structure-function relationship analysis, the common structural features and characteristic of Cu/ZnSOD was present in SOD_Cl, for example the binding of metal cofactor that involves the electrostatic loop.