What is the difference between organic chemistry and biochemistry?

1 Answer
Oct 31, 2015

In essence, biochemistry is like organic chemistry at #37^"o""C"# and #"pH 7.4"#, focusing on amino acid chemistry, proteins, enzymes, etc. The main difference is the greater focus on biological areas of the body.

You can deal with much of what you learn in biochemistry by using knowledge you learned from organic chemistry, like pKas, functional groups, and reaction mechanisms. You can draw plenty of similarities, like:

  • an enzyme is a catalyst, which involves a reaction coordinate diagram, which you've seen in organic chemistry I
  • an enzyme mechanism involving the SHD triad (serine, histidine, aspartate) follows a mechanism of amide hydrolysis into a carboxylic acid, which you learned in organic chemistry II
  • amino acids have sidechain pKas, while you probably learned pKas extensively in organic chemistry for such compounds as acetone (20), hydronium (-1.7), ammonium (9.4), ammonia (36), water (15.7), and acetylene (25).
  • etc.

Some common differences going from organic to biochemistry:

  • You can only perform the chemistry that your body is capable of (no random application of protecting groups to raise pKas, for instance!)
  • You shouldn't change the pH in the reaction system, because that stabilizes much of your body. Instead, you can influence pKas using particular hydrophobic or hydrophilic microenvironments
  • Changing the temperature isn't a good idea, because you can ruin the proteins in your body
  • Can't really change the pressure in your body!
  • etc.