MBIO 2360 Lecture Notes - Lecture 20: Glutamine, Hexokinase, Activation Energy
1 Dec 2016
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Example of electron carriers: oxidation-reduction reactions in the cell involve specialized electron carrier coenzymes. Nad (nicotinamide adenine dinucleotide) and nadp (nicotinamide adenine dinucleotide phosphate) Derived from niacin, one of the b vitamins. 1 proton, 2e- and one proton stays in solution. Nad usually accepts e- from catabolic degradation and nadh delivers the e- to the respiratory chain. Nad+ +2e- +2h+ --> nadh + h+ Fad (flavin adenine dinucleotide) and fmn (flavin mononucleotide) Flavin nucleotides, tightly bound prosthetic groups of flavoproteins. Accepts 2 hydrogen atoms (h=1e- + h+) The affinity of an atom or molecule for electrons can be measured: measurement of reduction potential. Use a voltmeter to measure voltage differences between two half cells. Redox reactions are divided into their components or half reactions. By convention, both half reactions are written as reductions. Obviously a great range of oxidations/reductions is possible and we need a system for comparing the relative ease or favourability of these reactions.
