NMR of red cells: plasma membrane oxidoreductase, and cation transport [ 2000 - 2002 ]

Research Grant

Researchers: Prof Philip Kuchel (Principal investigator)

Brief description An interesting paradox exists with respect to the 'central' function of the red blood cell (RBC): it delivers the main oxidising capacity to the body (O2), but it also carries the chemically opposite functionality in its membrane, namely reducing capacity. The reduction of many oxidised proteins and metabolites in blood plasma is mediated by a plasma-membrane oxido-reductase (PMOR). Ascorbic acid (vitamin C) dramatically accelerates this rate of reduction but its precise molecular role is unknown; neither is the immediate source of the reducing equivalents (electrons) known. Novel, non-invasive, 13C NMR methods have been developed, and others are planned in this project, to study the rate of reduction of Otest? compounds, including 13C-ferricyanide, and reactions of 13C-ascorbate. This will provide a quantitative understanding of the kinetics of the redox reactions in the intact cell. The transfer of negative charges (electrons) from the cell, in the longer term (minutes) inevitably must be matched by the movement of cations (positive charges). The main cation flux is mediated by Na+, K+-ATPase, but various cation exchange pathways are also involved in the total Oionic economy? of the cell. Of special interest will be the calcium-activated K+ (or Gardos) channel. This Oopens? inappropriately in malaria, sickle cell anaemia, and under blood bank storage conditions, and this is thought to be the basis of some of the pathological events in these conditions. The alkali-metal cation exchange pathway ( Na+-Li+) is more activate in the red cells of many patients with hypertension. So, multiple-quantum NMR methods will be used to monitor membrane transport and binding of cations to characterise the kinetics and regulation of the K+-channel, and the Na+-Li+ exchange reactions. The significance will lie in a basic understanding of, and possible 'diagnostic methods' for the biochemical processes that occur in red blood cells in health and disease.

Funding Amount $AUD 192,388.86

Funding Scheme NHMRC Project Grants

Notes Standard Project Grant