Enzymes

what do the enzymes produced by frontal lobes regulate?

From <a id="null" class="null" href="http://sciencemeetsfood.org/food-fire-frontal-lobe/">http://sciencemeetsfood.org/food-fire-frontal-lobe/</a>

While hydrogen sulfide can be generated from L-cysteine through three different enzymatic pathways available to all cells, the enzymes used to produce hydrogen sulfide from D-cysteine were only found in the kidneys and the brain.  And when D-cysteine and D-cystine, the oxidized form of D-cysteine, were given to mice neuron cell cultures treated with toxic levels of hydrogen peroxide, they were able to more effectively save the neurons from cell death than L-cysteine, presumably because transport of D-cysteine into neurons is faster than L-cysteine.  Moreover, they provided evidence that D-cysteine does not cause excitatory neuron damage to brain tissue, whereas L-cysteine administered directly to the brain has been shown to cause neuronal cell death.  They further suggested that the only source of D-cysteine for humans is from the racemization process induced by heat- or alkaline-treated food, as mammalian cell tissues do not have the enzymatic equipment to racemize cysteine into the D-form [7].

We can see here that cooking food gave a powerful biochemical advantage to early evolving hominids: it created a large reservoir of D-cysteine that could be directly shunted to and used almost exclusively by the brain.  Our brain utilizes 20% of all the energy reserves of the body [8], which requires a massive turnover of ATP, the energy currency used by living organisms.  As ATP is produced through the process of aerobic respiration in the mitochondria, a large amount of reactive oxygen species (ROS) is produced as a byproduct.  These ROS can wreak havoc on neurons as they react and tear apart the fat-containing myelin sheath that acts as insulation to increase the rate of transmissions between neurons.  The excess hydrogen sulfide generated from D-cysteine could have helped protect the ever-growing brain from damage from ROS.  Much like coolant is needed to keep computer processors from overheating, D-cysteine protected the brain from over-oxidizing.  In this instance, D-cysteine

the amount of nutrients that humans consume makes the amount of available cysteine irrelevant.  Cysteine is found in most high protein foods, such as meat, eggs, milk, legumes, soybeans, oats, and wheat.  Most people in the world can obtain enough cysteine to survive and thrive without suffering major setbacks in their neurological development because of the relatively high abundance of these foods thanks to modern agriculture.  However, some mental and psychiatric disorders are hypothesized to be dependent on hydrogen sulfide concentrations; for example, individuals affected by Alzheimer’s have been shown to have severely decreased levels of hydrogen sulfide in their brain [9].  Further research will be needed to determine the true importance of D-cysteine in our evolution by considering the evolutionary genetics of the D-cysteine metabolizing enzymes, the relative importance of D-cysteine in human physiology, its role in brain development and health, and if there are specific nutritional requirements for this ‘unnatural’ amino acid, created using the oldest technology of humankind.

The process of oxidative phosphorylation, the last step in aerobic respiration. Retrieved from https://www.khanacademy.org/science/biology/cellular-respiration-and-fermentation/oxidative-phosphorylation/a/oxidative-phosphorylation-etc

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rise of autoantibodies against key enzymes in energy metabolism causing defective aerobic energy metabolism and PEM (post exertional malaise)