Directed evolution: engineering biocatalysts

Lectures: 1 session / week, 2 hours / session

It is recommended that students should have completed both General Biochemistry (7.05) (or Biological Chemistry, 5.07) and, ideally, Cell Biology (7.06) before taking this seminar.

Enzymes, nature's catalysts, are remarkable biomolecules capable of extraordinary specificity and selectivity. These characteristics have made enzymes particularly attractive as an alternative to conventional catalysts in numerous industrial processes. Oftentimes, however, the properties of an enzyme do not meet the criteria of the application of interest. While biological evolution of an enzyme's properties can take several million years, directed evolution in the laboratory is a powerful and rapid alternative for tailoring enzymes for a particular purpose. Directed evolution has been used to produce enzymes with many unique properties, including altered substrate specificity, thermal stability, organic solvent resistance and enantioselectivity — selectivity of one stereoisomer over another. One example is the improvement of the catalytic efficiency of glutaryl acylase, an important enzyme in the manufacturing of semi-synthetic penicillin and cephalosporin. The technique of directed evolution comprises two essential steps: mutagenesis of the gene encoding the enzyme to produce a library of variants, and selection of a particular variant based on its desirable catalytic properties. In this course, we will examine what kinds of enzymes are worth evolving and the strategies used for library generation and enzyme selection. We will focus on those enzymes that are used in the synthesis of drugs and in biotechnological applications.

This course consists of 14 sessions focused on the reading and discussion of primary scientific literature that pertains to the course topic. Each student is expected to read the assigned two papers per week and participate in the discussion about the assigned literature. Each week, in addition to the class discussion of assigned papers, the instructor will present the techniques necessary for the reading and understanding of the following week's papers.

Grading in this course is pass/fail and will depend on student attendance, participation in class discussions and completion of the required assignments.

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