The enzyme glutamate dehydrogenase (GDH) plays an important role in integrating mitochondrial metabolism of amino acids and ammonia. Glutamate may function as a respiratory substrate in the oxidative deamination direction of GDH, which also yields α-ketoglutarate. In the reductive amination direction GDH produces glutamate, which can then be used for other cellular needs such as amino acid synthesis via transamination. The production or removal of ammonia by GDH is also an important consequence of flux through this enzyme. However, the abundance and role of GDH in cellular metabolism varies by tissue. Here we discuss the different roles the house-keeping form of GDH has in major organs of the body and how GDH may be important to regulating aspects of intermediary metabolism. The near-equilibrium poise of GDH in liver and controversy over cofactor specificity and regulation is discussed, as well as, the role of GDH in regulation of renal ammoniagenesis, and the possible importance of GDH activity in the release of nitrogen carriers by the small intestine.
Even though the standard solar model (SSM) has been very successful in predicting the thermal and nuclear evolution of the Sun, it does not throw enough light on solar magnetic activity. In the absence of a generally accepted theory of solar dynamo, various general arguments have been put forth to constrain solar magnetic fields. In the absence of reliable knowledge of solar magnetic fields from available astrophysical data, it may be worthwhile to constrain the solar magnetic fields from solar neutrino observations assuming Resonant Spin-Flavor Precession (RSFP) to be responsible for the solar neutrino deficit. The configuration of solar magnetic field derived in this work is in reasonably good agreement with the magnetic field distribution proposed by Akhmedov et al. (Sov. Phys. JETP68, 250 (1989)). However, the magnetic field distribution in the radiation zone used by Pulido (Phys. Rep.211, 167 (1992)) is ruled out. The magnitude of the magnetic field in the radiation and convective zones of the Sun are very sensitive to the value chosen for the neutrino magnetic moment. However, any change in the value of neutrino magnetic moment does not affect the magnetic field distribution as it only scales the magnetic field strength at different points by the same amount.
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