Breakdown of Large Molecules

This has already been covered to a large extent in the section on enzymes, e.g. proteinases, amylases, and various lipases. 

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Catabolism involves pathways composed of enzymes and chemical intermediates that are involved primarily in the breakdown of large molecules into small molecules, often by oxidation processes. Anabolism is the collection of the enzymes and chemical intermediates involved in the biological synthesis of larger molecules from smaller molecules. Anabolism often involves reduction processes. 

The Pittsburgh and Midway product from Merriam, Kansas, 122, is quite similar to the Tacoma SRC product, 308. The amount of solvent residue is very low. The solvent in both cases is of moderate molecular weight, and there appears to be very little breakdown of large molecules in the coal to produce either volatile compounds that would be left as residue in the product or to produce aromatic compounds that could be eluted in the column chromatographic analysis. 

We have now stated the central theme of this review. Several sections to follow are devoted to detailing the nature of our statement, and several sections to describing variations on the theme. Specifically, Section II describes the fundamental quantum mechanics of compound states, Section III contains a brief survey of the experimental data and theoretical background relevant to this review, and Section IV outlines the nature of the Born-Oppenheimer (BO) approximation and its breakdown in cases of interest. In Section V we consider the nature of the eigenstates of large molecules and the implications of the breakdown of the BO approximation. This leads us to discuss, in Section VI, a simple model of the time evolution of the states of large molecules and an interpretation of the... 

We shall now demonstrate that the breakdown of the BO approximation is a general phenomenon which occurs in all excited electronic states of large molecules. 

One of the steps in the cracking of petroleum into gasoline involves the thermal breakdown of large hydrocarbon molecules into smaller ones. For example, the following reaction might occur ... 

Acid-base reactions occur frequently in the synthesis and breakdown of large biological molecules. 

The synthesis of large molecules from smaller compounds involves the net reduction of carbon, as in the synthesis of glucose from carbon dioxide during photosynthesis, or the synthesis of lipids from carbohydrate by animals. If synthesis and breakdown were the exact opposites of each other, there would be no way for an organism to... 

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