Lecture #35

More applications

  CURMUDGEON GENERAL'S WARNING. These "slides" represent highlights from lecture and are neither complete nor meant to replace lecture. It is advised not to use these as a reliable means to replace missed lecture material. Do so at risk to healthy academic performance in 09-105.
Lecture outline Hemoglobin (conclusion)

Proteins and Amino acids

  • alpha amino carboxylic acids
  • side groups (polar vs nonpolar)
  • peptide bond
The capture and release of H+ by hemoglobin when oxygen is released to "burn" glucose or picked up from the air in lungs, respectively, facilitates the release of CO2 from dissolved bicarbonate and removal of CO2 waste into blood plasma at the glucose oxidation sites.
Proteins are made of amino acids. Here is an introduction to amino acid structure.
 Although there are countless millions of amino acids possible, only 20 play a role in biological systems for the most part. These split into those with polar and nonpolar side groups. The text has them in Figure 11-36
 This presents six of twenty amino acids in which the polarity of the side groups is called attention to.
 At pH around 7, an amino acid actually exists as a structural isomer called a zwitterion, shown here.
 With the exception of glycine, amino acids are chiral, having tetrahedral carbons with four different groups present.
 In building proteins from amino acids, the links between amino acids are "peptide bonds" described here.
 The sequence of amino acids in a polypeptide (protein) is referred to as the primary structure.
The number of variations of amino acids in polypeptides is enormous. For 5 different amino acids in a pentapeptide, thre are 120 possible different structures.
Part of what contributes to the final structure of the protein in 3D is the rigidity of the peptide bond due to its partial double bond character.