| Summary: | 碩士 === 國立臺灣大學 === 生化科技學系 === 100 === Lingzhi, a popular medicinal edible mushroom, has been used in Asia for the past 2000 years. The antitumoral and immune-stimulating effects of Lingzhi are attributed to polysaccharides, triterpenoids and fungal immunomodulatory proteins (FIPs). This study investigated GMI, a FIP cloned from Ganoderma microsporum and expressed in a methytrophic yeast, Pichia pastoris. The native form GMI is a noncovalently linked homodimer, and the monomer consists of 111 amino acids, with molecular weight of 12.4 kDa.
In this study, three different point mutation GMIs here made at the sixth residue, from leucine (L) to cysteine (C), lysine (K) and phenylalanine (F) respectively, resulting of the mutant GMIs, GMI-L6C, GMI-L6K and GMI-L6F. These mutants and wild type GMI here used to study the role of dimerization in immune modulatory functions and protein structure. GMI-L6C is able to form a stable homodimer via the formation of a disulfide bond. GMI-L6K and GMI-L6F tend to be pure monomer due to the positive charge or steroic conformation. Based on the results of the immune cell assays and nanoparticle analyzer, homodimer form GMI-L6C is able to increase immune cells function, while the monomer form GMI-L6K and GMI-L6F are unable to enhance immune activity.
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