Phosphorylating enzymes add one or more phosphate groups to three amino-acid residues common in proteins serine, threonine, or tyrosine which activates the proteins; removing the phosphate reverses the process. The research goal is to learn exactly when proteins such as enzymes and receptors are switched on and off by phosphorylation, and which cells within a population respond to cause specific changes for example, during differentiation of a progenitor cell into its functional form.
To avoid killing cells or introducing modified proteins or foreign bodies that may alter their behavior, scientists can use a method called Fourier-transform infrared (FTIR) spectromicroscopy; because infrared light has lower photon energy than x-rays, it can peer inside living cells without damaging them. Different components and different states of the cell absorb different wavelengths of the broad infrared spectrum; applying the Fourier-transform algorithm allows signals of all frequencies to be recorded simultaneously, pinpointing when, where, and what different chemical changes are occurring.
Most infrared sources are dim, however, so the information from typical IR set-ups is limited in resolution and has a low signal-to-noise ratio. Infrared from the ALS's synchrotron light source is a hundred to a thousand times brighter.
Previously Holman and her colleagues have used IR beamline 1.4.3, managed by Berkeley Lab's Michael Martin and Hans Bechtel, to obtain spectra from living organisms in rock, soil, and water. They have monitored ongoing biochemistry within living bacteria adapting to stress, and more recently within individual skin connective tissue cells (fibroblasts) from patients with mitochondrial disorders. (Mitochondria are the cellular organelles commonly known as the "power-plants" of the cell.)
The present study was done with a line of cultured cells called PC12. When
|Contact: Paul Preuss|
DOE/Lawrence Berkeley National Laboratory