BE.342/442 Tuesday, November 29, 2005 Topic: Prof. Zhang’s research AdministrativeNext time, on Thursday, Dr. Andreas Mershin from Prof. Zhang’s lab will share a variety of work in tissue engineering and other topics. Take-home midterms will be returned on Thursday as well. You will never learn what is bigger than the questions you ask.Ask big questions in research. Build from the bottom up instead of from the top down. That was, small structures and motifs can assemble into larger structures. For example: The Great Wall of China is made of 10x20x30 cm bricks… 3 billion of them! Schools of sardines are composed of individual fish 5 to 50 cm long. Together, the fish form ordered structures with remarkable patterns. Prof. Zhang’s research began in 1992 and ‘93, and people sometimes doubted his research ideas, or even thought they were nuts! Now, the Laboratory for Molecular Self-Assembly now includes a stem cell biologist, a structural biologist, a biochemist, a specialist on x-ray diffraction (who lectured for us earlier), a student from a contact lens company in Japan, and others. About 10 years ago, Prof. Zhang began work on self-assembling peptides. They began as fibers with hydrophobic cores, which self-assemble into gels. Second, the peptides were designed to form tubes with nanoscale dimensions. Third, functionalized peptides were created to form “molecular ink” that sticks to a substrate. Finally, a “molecular switch” was created from a protein with oppositely charged residues on its two ends, allowing it to undergo a conformational change. “Designer peptides” can be created to self-assemble through weak interactions, including: - Hydrogen bonds - Ionic bonds (electrostatic, “salt bridges” in biology such as coiled coils) - Van der Waals interactions
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