This award supports the development of a novel multiphoton microscope that will be capable of measuring biomolecular dynamics over 15 orders of magnitude in time. The microscope will use microfluidics technology to provide microsecond time-scale mixing, and low (ml/hour) sample consumption rates. Microsecond to second time scale delays will be achieved by using a microscope to probe the sample flow at increasing distances (corresponding to increasing time) along the outlet channel. The optical system will implement three pulse echo peak shift spectroscopy (3PEPS), a four-wave mixing method that has proven useful for measuring the spectrum of fluctuations of cofactor-containing proteins. The microscope will initially be employed in two lines of work: 1) studying the evolution of flexibility and heterogeneity during protein folding and 2) characterizing the dynamics of intermediate species in the photocycle of photoactive yellow protein.
Direct measurements of the molecular motions of biomolecules over a broad time range is crucial to furthering a microscopic understanding of biology. To fully appreciate the relation between molecular motions and biochemical events, the time scale over which molecular dynamics must be recorded is enormous - from femtoseconds (10-15 seconds) to seconds or even minutes. This collaborative work brings together the expertise of an optical physicist, chemical engineer, and biophysicist, to develop instrumentation that will advance knowledge in biomolecular dynamics. This new instrumentation will stimulate broader application of powerful femtosecond nonlinear optical techniques to biochemical studies, and will further develop technologies with great promise in biological studies: multiphoton microscopy and microfluidics. This research will benefit interdisciplinary biophysics education at the undergraduate and graduate levels by providing opportunities for students to work in multidisciplinary teams including molecular biologists, chemical engineers, and optical physicists.
