Relaxometric studies are still of scientific interest due to their use in medicine and biology. In this study, proton T1 and T2 relaxivities of Mn(II), Cu(II) and Cr(III) in water were determined in the presence and absence of various proteins (albumin, α-globulin, γ-globulin, lysozyme, fibrinogen). The 1/T1 and 1/T2 in all solutions are linearly proportional to the concentration of the paramagnetic ions. Mn(II) has the great influence to alter relaxations in all protein solutions, while Cu(II) and Cr(III) have a poor influence on the relaxations. In addition, Mn(II) and Cu(II) are bound to each protein, but Cr(III) is not bound to any protein.

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Macromolecular crowding is a general phenomenon of biological systems, and the evaluation of a correlation time for a specific molecule is difficult when the molecular crowding exists. The determination of an effective correlation time may therefore give useful insights into molecular dynamics of such systems. In this work, the relaxation rates in the mixture of D2O (80%) and cystic fluid (20%) were measured with a NMR operating at 400 MHz for three types of cysts (non-infected radicular, infected radicular and hemorrhagic). The effective correlation times (τvalues) were then determined by using a formula derived from the observed relaxation rates. Theτvalue of the infected cyst was found to be longer than those of the others for the studied cases. The present data suggest that an effective correlation time for fluids with macromolecular crowding can be determined from NMR relaxation measurements.

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