Structures and Analyzing Cells

How have chemists deduced the thousands of structural formulas thaf we wrife for fhe subsfances found in nature The answer is far too complex to give here in detail. However, the separation of compounds, the analysis of mixtures, and the unraveling of structures remain essential parts of biochemisfry. 

A minireview of mefhods, with emphasis on proteins, follows. Addifional procedures having to do primarily with carbohydrates, nucleic acids, or lipids are given in Chapters 4,5, and 8, respectively. 

For a compound containing several acidic groups we define a series of consecutive dissociation constants Kjg, fC2a, K33, etc. For the sake of simplicity we will omit the a s and call these Ky Ky Ky-. 

The strength of an acid is usually described by the acid dissociation constant K 

If there are n consecutive dissociahon constants there will be n + 1 ionic species H3A, HjA, etc. Notice that H3A could be a neutral molecule with H2A, HA, and A bearing changes of -1, -2, and -3, respectively. Alternatively, H3A might carry 1, 2, or 3 positive changes. 

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