Biochemistry Part IV - (Proteins)

3. Proteins Molecules containing carbon, hydrogen, oxygen, & nitrogen. These are very poor sources of energy, however they are AWESOME building blocks during growth, development and repair. They are also used as hormones, antibodies, and enzymes! Model of an enzyme, PanC.

Proteins (cont’d) The building blocks of proteins are amino acids. There are slightly more than 20 found in nature. Recall from fats/lipids, all acids have a carboxyl group (COOH) at one end. This applies to amino acids, just as it applies to fatty acids.

Proteins (cont’d) At the other end of an amino acid, however, is an amino group (-NH2). Since all amino acids have both of these “end arrangements”, they can join by bonding the amino group at one end with the carboxyl group of another amino acid.

Proteins (cont’d) The only part of an amino acid that differs from other amino acids is the “R” group, which is the middle arrangement of atoms. R Group Amino group Carboxyl group Alanine Serine Glycine

Proteins (cont’d) The sequences of amino acids is critical when building a protein! Hemoglobin is a blood protein that carries oxygen. It is composed of 146 amino acids. If ONE of those 146 is out of place – sickle cell anemia!

Proteins (cont’d) With this disorder, certain circumstances (such as low oxygen supply) cause red blood cells to deform into the classic sickle shape; hemoglobin becomes rigid and these cells are easily trapped in small blood vessels and capillaries. This is painful and can lead to organ damage.

There are many different kinds of proteins, for the following reasons: 20+ amino acids can make an almost infinite variety of lengths and combinations, each sequence of which codes for a specific protein! The amino acids within a chain can be folded or twisted. The chain itself can be folded or twisted. Proteins can have more than one chain of amino acids involved.