Physiological metabolic enzymes and tissue water proton relaxation

Physiological metabolic enzymes and tissue water proton relaxation refers to a biophysical phenomenon rather than a specific molecular target. It describes the relationship between the concentration, conformational state, and catalytic activity of intracellular enzymes and the magnetic resonance imaging (MRI) relaxation parameters (T1 and T2) of water protons in biological tissues (Bryant, R. G., 1996, Progress in Nuclear Magnetic Resonance Spectroscopy). This effect is primarily mediated by the chemical exchange of protons between water and ionizable protein groups, as well as dipole-dipole interactions within the hydration shells of macromolecules. Changes in metabolic flux or enzyme expression, which are common in pathological states such as cancer or ischemia, significantly alter these relaxation rates, providing a basis for endogenous MRI contrast (Hills, B. P., 1992, Molecular Physics). While this concept is fundamental to the development of metabolic imaging and the use of relaxation times as biomarkers for tissue health, it does not represent a single protein or receptor that can be directly modulated by pharmacological agents. Instead, it serves as a diagnostic framework for monitoring physiological changes and therapeutic responses in vivo (Gore, J. C., et al., 1984, Magnetic Resonance Imaging).

Other names

Tissue water proton relaxationMetabolic MRI relaxationEnzymatic water relaxation enhancement