Ph.D. National Taiwan University
1. Ribonucleases with antitumor activity are mainly found in the oocytes and embryos of Rana catesbeiana (bullfrog), but the mechanism of antitumor activity and their roles in frog development are not clear. The residues involved in catalytic activity base recognition and cytotoxicity are investigated by site-directed mutagenesis, NMR and X-ray cocrystallography.
2. Antimicrobial peptides/proteins (AMPs) are important components ofthe host innate defense mechanisms against invading microorganisms.The human ribonuclease 7(hRNase 7) possesses membrane permeability and antimicrobial activity through the flexible and clustered lysine residues near N-terminus. In addition to hRNase 7, hundreds of AMPs also exert similar antimicrobial activity. The susceptibility of Gram negative bacteria to these AMPs is determined by an outer membrane protein, like the OprI of Pseudomonas aeruginosa and Lpp of E. coli. Therefore, OprI and its homologues may be used as ligands for the screening and production of antimicrobial materials.
3. The removal of N-terminal Met is often crucial for the function and stability of recombinant proteins. We engineer an E. coli methionine aminopeptidase (MetAP) which is able to remove N-terminal Met from bulky or acidic penultimate residues.