| Land plants and bacteria are major sources of various biomolecules such as sugars, lipids, proteins, vitamins, flavonoids and so forth. These materials are synthesized in living organisms by means of step-specific catalytic enzymes. We are working on engineering of several enzymes that catalyze key steps of chemical conversions in the biosynthesis of particular molecules. For the enzyme for which structural information is available, as a main approach, in vitro system, that is the combination of the cell-free protein synthesis system and the site-directed PCR mutagenesis, is used for functional screening of mutant proteins. This system enables us to create enzymes acquired new functions that are desired for industrial applications. Recently, we succeeded in creation of functionally modified rice enzyme (OASA2), which was available for generating crops accumulating high concentration of tryptophan. We are also working on the alteration of substrate specificity of bacterial enzymes. In the case of enzyme for which structural data is not available, we take random mutagenesis approach for screening functionally altered proteins. The goal of this work is establishment of novel biosynthetic pathway to produce desired biomolecules in land plants or bacteria. |
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