Sarcoplasmic reticulum nuclear

The present paper will outline some of our recent EPR and NMR studies using Mn2+ as a paramagnetic probe of sheep kidney (Na+ + K+)-ATPase and Gd2+ as a paramagnetic probe of sarcoplasmic reticulum Ca2+-ATPase. Estimates of the relevant electron spin relaxation times and some features of the interaction between substrates and activators with the enzyme-metal complexes will be inferred from the EPR spectra and the accompanying nuclear relaxation data. 

In order to characterize the active site structure of Ca ATPase from sarcoplasmic reticulum, we have employed Gd + as a paramagnetic probe of this system in a series of NMR and EPR investigations. Gadolinium and several other lanthanide ions have been used in recent years to characterize Ca + (and in some cases Mg2+) binding sites on proteins and enzymes using a variety of techniques, including water proton nuclear relaxation rate measurements (35,36,37), fluorescence (38) and electron spin resonance (39). In particular Dwek and Richards (35) as well as Cottam and his coworkers (36,37) have employed a series of nuclear relaxation measurements of both metal-bound water protons and substrate nuclei to characterize the interaction of Gd + with several enzyme systems. 

NFAT nuclear factor of activated SR sarcoplasmic reticulum... 

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