Amino Acids and Proteins Overview

Amino Acids and Proteins

• Proteins are the building blocks of the body's structures and perform various biological activities.
• Amino acids are the building blocks of proteins.
• About half of the 20 amino acids must be supplied through diet.

Classification of Amino Acids

• Amino acids have both an amino group and a carboxylic acid functional group.
• Alpha-amino acids have an amino group bonded directly to the alpha-carbon.
• Every amino acid has an alpha-carbon, a carboxyl group (COOH), an amino group (-NH2), a hydrogen atom, and a unique R group.

Peptide Bonds

• Peptide bonds form between the carboxyl group of one amino acid and the amino group of another.
• These bonds create the polypeptide chains that are the backbone of proteins.

Amino Acids (Essential vs. Nonessential)

• Essential amino acids cannot be produced by the body and must be obtained from the diet.
• Nonessential amino acids can be produced by the body.
• The slide lists specific essential and nonessential amino acids.

Amino Acid Synthesis

• Proteolytic enzymes (such as Pepsin and Trypsin) break down dietary proteins into amino acids.
• The body breaks down amino acids to make proteins.
• Deamination removes the amino group from amino acids.
• Transamination transfers amino acids.

Aminoacidopathies

• Aminoacidopathies are inherited errors of metabolism.
• Deficiencies in enzymes related to amino acid metabolism can cause issues.
• Conditions like phenylketonuria (PKU) and tyrosinemia lead to specific symptoms.
• Screenings detect these conditions early. Diagnostic methods include Guthrie test and others.

Protein Structure

• Primary Structure: The linear sequence of amino acids linked together.
• Secondary Structure: Repeating structures stabilized by hydrogen bonds, forming alpha-helices, beta-sheets, and turns.
• Tertiary Structure: The overall 3D shape of a protein molecule, with interactions among amino acids.
• Quaternary Structure: The shape resulting from multiple protein molecules interacting. Hemoglobin is an example.
• Denaturation: Disruption or alteration of protein structure, leading to loss of function due to heat, strong acids/alkalis and other agents.

Properties of Proteins

• Proteins are described by their content, charge, solubility, immunogenicity, and synthesis capability.
• Proteins contain carbon, hydrogen, oxygen, sulfur, and nitrogen; unlike lipids and carbohydrates which don't have nitrogen.
• Charge of protein depends on surrounding pH, and the isoelectric point (pI).
• Solubility depends on the charge of protein surface.

Functions of Proteins

• Proteins have diverse functions, including enzymatic activity, hormone reception, transport of molecules (like oxygen), immunological defense, structural components (tissues), storage of energy, and generating osmotic force to maintain the internal environment of the body.
• The slide lists these broad functions, with details about specific proteins involved.

Classification of Proteins

• Simple Proteins: Made up of only amino acids. Examples include albumin and globulins.
• Conjugated Proteins: Composed of a protein and a non-protein group (prosthetic group). Examples include glycoproteins, lipoproteins, and others.

Plasma Proteins

• Albumin is the most abundant plasma protein, maintaining blood pressure and transporting other molecules. Abnormal levels can indicate serious conditions.
• Globulins are a diverse group of proteins with various functions, including maintaining osmotic pressure, fighting infection (antibodies), carrying iron (transferrin), and other roles.
• Specific globulin types are listed with their associated diseases, like alpha-1 antitrypsin deficiency, and conditions associated with elevated or decreased levels.

Other Plasma Proteins

• The section includes different important proteins, e.g., myoglobin, cardiac troponins, and the role of these proteins in clinical settings including diagnostics.

Proteins in Other Body Fluids

• Urinary proteins are indicators of various diseases and are used for diagnosis and monitoring in conditions like kidney disease, multiple myeloma, and diabetes etc.
• CSF protein levels provide critical information about conditions affecting the brain and spinal cord.