Chapter 16 - Amino Acids, Proteins, and Enzymes

16.1 - Proteins and Amino Acids

• In structure, transport, protection, storing, and muscle contraction, some proteins are enzymes or hormones.
  • Some proteins are important.
  • Molecular protein building blocks are provided by a group of 20 amino acids.
• An ammonium group, a carboxylate group, and a single R group are attached to the central carbon for each amino acid.
  • The group R has a non-polar, polar, acidic, or fundamental characteristic of amino acid.

16.2 - Proteins: Primary Structure

• Peptides are produced when the amide bond connects one amino acid to the ammonium group of the second amino acid carboxylate group
• Long chains of biologically active amino acids are known as proteins.
• Essential amino acids must not be produced in the body by dietary proteins.
• An amino acid sequence combined with peptide bonds is a primary structure of the protein.
• The N-terminus peptides are designated to substitute for the Ine or Ate of every amino acid name, followed by the C-terminus amino acid name.

16.3 - Proteins: Secondary, Tertiary, and Quaternary Structures

• The secondary structure produces a characteristic shape such as a helix
• The tertiary structure is stabilized by interaction with hydrophobic R-groups and by the interaction between R-groups that form hydrogen, disulfide, and salt bridge-bonding amino acids.
  • It also helps to pull amino acids on the surface with hydrophobic R.
• Two or more tertiary subunits for biological activity in a quaternary structure are joined together and the interactions in third structures are identical.
• A protein denature occurs when the secondary, tertiary, or four-part protein structures with loss of biological activity destroy high temperatures, acids or bases, organic compounds, metal ions, or agitation.

16.4 - Enzymes

• Protein is the majority of enzymes.

• As biological catalysts, enzymes act by reducing activation energy and accelerating cell response rates.

• A small pocket known as the active site binds the substratum within the tertiary structure of the enzyme.

  • A substrate fits the shape of the active site exactly in the lock-and-key model.

• The active site and the substratum undergo a change in shape in the induced adaption model, which makes them best suited for effective catalysis.

• Catalysis occurs at the enzyme-substrate complex when amino acid R groups interact with a substrate in the active site of the enzyme

  • The enzyme can bind to another substrate molecule when the products of catalysis are released.

  

16.5 - Factors Affecting Enzyme Activity

• The ideal temperature for most enzymes is normally 37°C and the optimum pH is generally 7.4.

  • Rate declines as temperature and pH are above and under optimum temperature and pH values for an enzyme-catalyzed reaction.

• The activity of an enzyme is reduced or made inactive by an inhibitor.

  • A reversible or irreversible inhibitor.

• A competitive inhibitor has a substrate-like structure and is competing for the active location.

• A non-competitive antimicrobial inhibitor attaches both the shape of the enzyme and its active site to the active site.

• A covalent binding in the active area forms an irreversible inhibitor, which prevents catalytic activity permanently