Bounds on "bound water": transverse nuclear magnetic resonance relaxation in barnacle muscle

Relatively mobile protons that do not exchange with D2O exist in barnacle muscle cells. These are not part of the nonfreezing "bound water" that does exchange. Ninety-seven percent of the muscle water exhibits a single transverse relaxation time of 35 milliseconds: one water molecule per thousand, which is briefly and irrotationally bound, will produce the observed relaxation properties.