Nutrikine
Recent data suggest that certain diseases are due, in part, to a decrease in the function of a variety of the zinc dependent enzymes, which results from changes in zinc pharmacokinetics. Appreciation for the apparent changes in zinc homeostasis has compelled researchers to undertake zinc supplementation trials, attempting to restore zinc concentrations locally in affected tissues. Although this approach has been marginally successful in a handful of diseases, the approach fails to appreciate fundamental aspects of zinc biochemistry. As a trace nutrient, the intracellular concentration of available zinc is quite low. Although the concentration is not known precisely, it is believed to be in the low nanomolar range. For each cell to function optimally, it must maintain a specific concentration of free zinc (the so-called zinc window). This concentration is controlled and maintained by the coordinated influx and efflux of zinc ions from intracellular sites and across the plasma membrane. This movement is controlled by specific membrane-bound transport proteins. Uptake is mediated by the ZIP family of proteins while efflux is mediated by a different set of protein transporters. The foundation of this work has been provided by studies of the macronutrients, and calcium in particular. However, unlike the abundant macronutrients that are present in micromolar concentrations, the trace nutrients typically are present in nanomolar concentrations (ie, concentrations that are below the Km of the transporter which are inadequate to “activate” the protein to drive their transport). Consequently, movement of zinc across membranes also must rely upon intracellular and extracellular “shuttle” molecules, that increase the effective concentration of zinc in the vicinity of the transporters.
The name “nutrikine” has been given to those compounds that keep us healthy by regulating trace nutrient pharmacokinetics. In addition to shuttling the nutrient to transporters, nutrikines also are involved in their gastrointestinal absorption, intracellular storage, intercellular distribution, metabolism, and elimination. Consequently, compounds that regulate the kinetic processes of zinc are referred to as “zinc nutrikines”.
NutrienTech LLC
