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MindTouch
http://mindtouch.com

This file and accompanying files are licensed under the MindTouch Master Subscription Agreement (MSA).

At any time, you shall not, directly or indirectly: (i) sublicense, resell, rent, lease, distribute, market, commercialize or otherwise transfer rights or usage to: (a) the Software, (b) any modified version or derivative work of the Software created by you or for you, or (c) MindTouch Open Source (which includes all non-supported versions of MindTouch-developed software), for any purpose including timesharing or service bureau purposes; (ii) remove or alter any copyright, trademark or proprietary notice in the Software; (iii) transfer, use or export the Software in violation of any applicable laws or regulations of any government or governmental agency; (iv) use or run on any of your hardware, or have deployed for use, any production version of MindTouch Open Source; (v) use any of the Support Services, Error corrections, Updates or Upgrades, for the MindTouch Open Source software or for any Server for which Support Services are not then purchased as provided hereunder; or (vi) reverse engineer, decompile or modify any encrypted or encoded portion of the Software.

A complete copy of the MSA is available at http://www.mindtouch.com/msa

In the graphic below, the structure for the coenzyme, NAD+, Nicotinamide Adenine Dinucleotide is shown. Nicotinamide is from the niacin vitamin. The NAD+ coenzyme is involved with many types of oxidation reactions where alcohols are converted to ketones or aldehydes. It is also involved in the first enzyme complex 1 of the electron transport chain.

One role of $$NAD^+$$ is to initiate the electron transport chain by the reaction with an organic metabolite (intermediate in metabolic reactions). This is an oxidation reaction where 2 hydrogen atoms (or 2 hydrogen ions and 2 electrons) are removed from the organic metabolite. (The organic metabolites are usually from the citric acid cycle and the oxidation of fatty acids--details in following pages.) The reaction can be represented simply where M = any metabolite.

$MH_2 + NAD^+ \rightarrow NADH + H^+ + M: + \text{energy}$

One hydrogen is removed with 2 electrons as a hydride ion ($$H^-$$) while the other is removed as the positive ion ($$H+$$). Usually the metabolite is some type of alcohol which is oxidized to a ketone.

### Alcohol Dehydrogenase

The NAD+ is represented as cyan in below the graphic. The alcohol is represented by the space filling red, gray, and white atoms. The reaction is to convert the alcohol, ethanol, into ethanal, an aldehyde.

$CH_3CH_2OH + NAD^+ \rightarrow CH_3CH=O + NADH + H^+$

This is an oxidation reaction and results in the removal of two hydrogen ions and two electrons which are added to the NAD+, converting it to NADH and H+. This is the first reaction in the metabolism of alcohol. The active site of ADH has two binding regions. The coenzyme binding site, where NAD+ binds, and the substrate binding site, where the alcohol binds. Most of the binding site for the NAD+ is hydrophobic as represented in green. Three key amino acids involved in the catalytic oxidation of alcohols to aldehydes and ketones. They are ser-48, phe 140, and phe 93.

### Contributors

17:00, 25 Feb 2014

## Classifications

(not set)
Lower Divisional

### Textbook Maps

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