Nadh ch

cooh acetate

9 enzyme-catalysed reactions (the citric acid cycle)

mitochondrial electron transport chain

Figure 2.17 The oxidation of ethanol. The box shows the rapid non-enzymic reaction when ethanol is burned in air; metabolic oxidation of ethanol involves 11 separate enzyme-catalysed steps, as well as the mitochondrial electron transport chain.

shown in Figure 2.18, in which an intermediate may proceed down one branch or another. The fate of an intermediate at a branch point will depend on the relative activities of the two enzymes that are competing for the same substrate. As discussed above (section 2.3.3), if the enzymes catalysing the reactions from D ^ P and from D ^ X have different values of Km, then it is possible to predict which branch will predominate at any given intracellular concentration of D.

Enzymes catalysing reactions at branch points are usually subject to regulation (section 10.1), so as to direct substrates through one branch or the other, depending on the body's requirements at the time.

Figure 2.18 Linear and branched metabolic pathways.

Drop The Fat Now

Drop The Fat Now

Statistics For Obesity Are Rising And The Majority Of People Are Not Getting Enough Exercise Nor Are Having Any Regard For Their Health! Will You Finally Make Good On Your Promise And Set Your Goals To Improve Your Fitness And Live The Healthy Lifestyle You Want? With A Little Bit of Motivation, You Can Set Yourself On the Correct Path To Losing Weight And Feeling Great Using Nothing But Purely Natural Means!

Get My Free Ebook

Post a comment