THIS PROJECT EXAMINES THE STRUCTURE OF THE TROPONIN C/TROPONIN COMPLEX USING HIGHFIELD NMR SPECTROSCOPY. THE TROPONIN C/TROPONIN COMPLEX SERVES AS A CALCIUM DEPENDENT MOLECULAR SWITCH THAT REGULATES MUSCLE CONTRACTION. THIS PROJECT IS EXAMINING THE STRUCTURE OF THE COMPLEX USING SOLUTION NMR TECHNIQUES. THE STRUCTURE IS BEING EXAMINED USING THE COMPLEX OF FULLY DEUTERATED TROPONIN C AND THE PROTONATED TROPONIN C BINDING DOMAIN FROM TROPONIN. IN THE DEUTERATED/PROTONATED COMPLEX WE CAN OBTAIN SPECTRA THAT ARISE ONLY FROM THE PROTONATED PARTNER. FROM THIS DATA WE WILL OBTAIN THE STRUCTURE OF THE TROPONIN PEPTIDE BOUND IN THE COMPLEX TO TROPONIN C. BY COMPARING STRUCTURE OF THE COMPLEX IN PRESENCE OR ABSENCE OF CALCIUM WE WILL DETERMINE THE MOLECULAR MECHANISM WHICH IS USED TO TURN ON AND OFF MUSCLE CONTRACTION. ISOTOPE LABELED SAMPLE OF TROPONIN AND TROPONIN C ARE BEING PRODUCED IN COLLABORATION WITH THE SIR.