Energy extraction in living systems is entirely dependent on electron flow. Biological redox reactions rarely involve free electrons; instead, they transfer hydride ions ( H−cap H raised to the negative power ) or hydrogen atoms via coenzymes like NAD+cap N cap A cap D raised to the positive power NADP+cap N cap A cap D cap P raised to the positive power FADcap F cap A cap D Key Biological Pathways Explained Chemically
Citrate synthase catalyzes the reaction between acetyl-CoA and oxaloacetate. The enzyme deprotonates the methyl group of acetyl-CoA to form a nucleophilic enolate, which then attacks the carbonyl carbon of oxaloacetate.
The Organic Chemistry of Biological Pathways: A Comprehensive Guide The Organic Chemistry Of Biological Pathways Pdf
Glucose is phosphorylated to trap it inside the cell and destabilize the molecule for cleavage.
In the first step, hexokinase catalyzes the transfer of a phosphate group from ATP to the C6 hydroxyl group of glucose. This is an SN2cap S sub cap N 2 mechanism at a phosphorus atom. Energy extraction in living systems is entirely dependent
Glucose-6-phosphate (an aldose) is isomerized to Fructose-6-phosphate (a ketose). This moves the carbonyl oxygen to carbon-2, setting up a perfect Aldol Cleavage between carbon-3 and carbon-4 later in the pathway. The Citric Acid Cycle (Krebs Cycle): Carbon Trafficking
Steps involving isocitrate dehydrogenase and -ketoglutarate dehydrogenase rely on electron sinks (like NAD+cap N cap A cap D raised to the positive power Glycolysis: The Universal Energy Pathway
The organic chemistry of biological pathways involves the study of the chemical reactions that occur within these pathways. This includes:
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To truly appreciate the organic chemistry of biological pathways, one must look at specific metabolic routes and analyze the chemical transformations taking place. 1. Glycolysis: The Universal Energy Pathway