Philip W. Brandt, Ph.D.
Muscle regulation and contraction
The research in my laboratory explores how cooperation between the proteins of the thin and thick filaments regulates muscle contraction. We use "skinned muscle fibers" made by placing small bundles of fresh rabbit psoas muscle in solutions designed to break down the cell surface membranes. Selected regulatory proteins are extracted and replaced with those made by genetic engineering or by modification of purified natural proteins. Fluorescent labels are often attached to the proteins before they are inserted into the filaments to follow changes in protein and filament conformation by fluorescence spectrometry and microscopy. Most experiments are done on computer controlled apparatus. For example, in a typical experiment a single fiber is dissected, modified then exposed to a series of increasing calcium concentrations while tension and fluorescence ratios are recorded. Our aim is to define the rapid restructuring of groups of molecules in the filaments that precede and accompany muscle contraction.
Fluorescence changes on contractile activation in TnCDANZ labeled skinned rabbit psoas fibers. J. Muscle Research and Cell Motility, 2001, in press.
Brandt PW, Colomo F, Piroddi N, Poggesi C & Tesi C. 1998. Force regulation by Ca2+ in skinned single cardiac myocytes of frog. Biophysical Journal, 74(4):1994-2004.
Brandt PW, & Schachat FH. 1997. Troponin C modulates the activation of the thin filament by rigor cross-bridges. Biophysical Journal. 72:2262-2267.
Brandt, P.W., Diamond, M.S., Rutchik, J.S. and Schachat, F.H., 1987. Cooperative interactions between troponin-tropomyosin units extend the length of the thin filament in skeletal muscle. J. Molecular Biol. 195:885-896.
Brandt, P.W., Diamond, M.S., and Schachat, F.H., l984. The thin filament of vertebrate skeletal muscle co-operatively activates as a unit. Journal of Molecular Biology. l80:379-l67.