Answers are grounded in this paper and cite their sources.
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.
No takes yet. Share an insight, caveat, or question.
Foster et al. (1976) studied this question.
Synapse has enriched 10 related papers. Consider them for comparative context: