PROTEINS

• Proteins


  Macromolecules composed of amino acids linked by peptide bonds
• CTTCFGAAGAR GAG GAGTCAGCTC 5570.00 + 5.00 5615.00 + 25.00 2342.00 + 3.00 2314.00 + 5.00 10.50 3.50 2.50 А ПЛ D 20 3040.44 078 9,99 211 232 1960658 287 8 194.04 0,90 1.13 6730,48 -547 147 1073.00 7165.00 250 4.00 25.00 1675.00 + 27.00 1541.00 1.00
• Protein Functions

  • Structure, protection, support
  • Defense and protection against chemical & mechanical injury
  • Regulation through the body hormones
  • Catalysis through enzymes
  • Transport as carrier of ions & molecules across cell membranes or between cells
• Amino acid


  Building blocks of proteins, linked by peptide bonds
• Peptide bond


  Covalent bond formed between the carboxyl group of one amino acid and the amino group of another, with the loss of a water molecule
• Dipeptide is two amino acids linked by one peptide bond
• Bonds that may be formed in proteins


  • Intramolecular disulfide bonds
  • Electrovalent salt bridges
  • Hydrophobic bonds
  • Hydrogen bonds
• Levels of protein structure


  • Primary: Amino acid sequence
  • Secondary: Presence of hydrogen bonds forming pleats or helices
  • Tertiary: 3D folding and twisting
  • Quaternary: Combination of multiple polypeptide chains
• Fibrous proteins


  Insoluble in aqueous media, high molecular weight, consist of long linear molecules arranged in parallel
• Fibrous proteins


  • Collagen, myosin, keratin, fibrin
• Globular proteins


  Soluble in aqueous media, crystallized with definite molecular weights, can be denatured
• Globular proteins


  • Enzymes, hormones
• Albumins


  Soluble in water, coagulated on heating
• Albumins


  • Egg albumin, serum albumin, lactalbumin
• Globulins


  Insoluble in water, soluble in dilute salt solutions but precipitated with high salt concentrations, coagulated on heating
• Globulins


  • Myosinogen, ovoglobulin, legumins
• Glutelins


  Insoluble in neutral solvents but soluble in dilute acids and alkalis
• Glutelins


  • Glutein from wheat, oryzenin from rice
• Alcohol-soluble proteins (Prolamines)


  Soluble in 70-80% alcohol, insoluble in water and absolute alcohol
• Prolamines


  • Gliadin from wheat, hordein from barley, zein from corn
• Histones


  Soluble in water and dilute acids, insoluble in ammonia, precipitated by solutions of other proteins, coagulum formed on heating
• Histones


  • Globulin from hemoglobin, thymus histone, sombrone from mackerel
• Protamins


  Polypeptides which are less complex, soluble in water, not coagulated on heating, precipitates other proteins from their aqueous solutions, forms stable salts with strong acids, forms basic amino acids on hydrolysis
• Protamins


  • Salmine from salmon, sturine from sturgeon, cyprinine from carp
• Types of conjugated proteins


  • Nucleoproteins
  • Glycoproteins
  • Phosphoproteins
  • Chromoproteins
• Types of derived proteins


  • Primary protein derivatives: Proteans, Metaproteins, Coagulated proteins
  • Secondary protein derivatives: Proteoses
• Beta-Sheet


  Type of protein structure
• Polypeptide


  A chain of amino acids
• Protein structure


  • 30 A
  • Tyr66
  • Alpha Helix
  • Ser65
  • Gly67
• Chromophore


  A part of a molecule responsible for its color
• Figure 1 shows Proteins: Classifications
• According to State of Degradation


  • Native Proteins
  • Derived Proteins
• Primary Protein Derivatives


  • Proteans
  • Metaproteins (infraproteins)
  • Coagulated Proteins
• Secondary Protein Derivatives


  • Proteoses
  • Peptones
  • Peptides
• According to Functional Classification


  • Storage
  • Enzymes
  • Hormones
  • Antibodies
  • Toxins
  • Special Purpose
• According to Nutritional Completeness


  • Complete
  • Partially Incomplete
  • Incomplete
• Proteins


  • High molecular weight
  • Constant solubility
  • Hydrolyzed by acids, alkalis, enzymes
• Precipitated by


  • Acids
  • Salts of Heavy Metals
  • Neutral Salts
  • Alcohols
• Proteins form complexes with


  • Nucleic acids
  • Carbohydrates
  • Pigments
  • Lipids
  • Enzymes
• Proteins combine with dyestuffs using picric acid and flavianic acid