Proteins
Proteins Numerous functions in the human body. Contain carbon, hydrogen, oxygen and nitrogen (and sulfur in some cases) Compose 12 to 18% of the lean adult human body More complex than lipids and carbohydrates Largely for structure of body tissues Largely responsible for metabolism Examples: enzymes, motors, pigments, antibodies, some hormones, ETC!!!
Amino Acids Amino acids are the building blocks of proteins Amino acids are joined together to form dipeptide, tripeptide, peptide and polypeptide chains This is the first level of organization of proteins There are 20 (22 in babies) amino acids that the human body uses to make proteins (almost always the “left handed” versions) 12 of these can be synthesized by the human body 8 must obtained from other sources, these are the ESSENTIAL AMINO ACIDS
Amino Acids There are common portions to amino acids. -Amino Group -Carboxyl broup -Hydrogen (side) -Side group
Amino Acids Amino acids link together at the carboxyl groups and the amino groups to form peptide bonds. This is the first (primarily level of organization:
Levels of Organization Secondary Structure: Tertiary Structure: Quaternary Structure:
Enzymes “Biocatylists” They are the same at the beginning of a reaction as they are at the end of a reaction. They don’t get used up in the reaction. They lower the activation energy of reactions They speed reactions up as much as 10 billion times Usually consist of 2 components: -Protein component: apoenzyme -Nonprotein component: cofactor -May be a metal ion -May be an organic substance (like a vitamin), then called a coenzyme
Activation Energy
Activation Energy
Enzymes Enzymes are highly specific, each will bind with only a specific substrate. They bind at the active site, which has a characteristic shape unique to that enzyme. 1000+ enzymes known in the human body. Many enzymes fit like “lock and key,” others will bend somewhat at the active site to produce an “induced fit.” Enzymes are highly efficient. Some enzymes will act on as many as 600,000 molecules in a second.
Enzymes Subject to a variety of cellular controls Chemical environment of the cytosol of a cell (such as pH, etc.) will often be that factor. -The chemical factors can change the forms of the enzyme from an active to inactive form and vice versa. -These chemical factors are often under the control of the genes of cells
Catalase
Enzyme Action