Protein hydration changes in the formation of the nicotinamide adenine dinucleotide complexes of glyceraldehyde 3-phosphate dehydrogenase of yeast. II. The spin lattice relaxation of solvent water protons

The glyceraldehyde 3-phosphate dehydrogenase of yeast is known to undergo a particle volume contraction and the commensurate loss of a hydration component when it forms a complex with NAD. We have inquired whether the water movement in the conformational transition can be monitored by measurements of the spin lattice relaxation rate, TI-1 of solvent water protons. In solutions of diamagnetic proteins, a class of bound water molecules is rapidly relaxed in the protein hydration domain and the relaxation is averaged in the bulk solvent by water exchange. T1-1 was found by pulse NMR (nuclear magnetic resonance) measurements to increase as a linear function of the apoprotein concentration.