Peptides (1. LF UK, NT)

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Structure

File:Formation of cyclic dipeptide.jpg

Classification[edit | edit source]

Number of bound monomers (amino acids)

  • oligopeptides (2–10 amino acids)
  • polypeptides (formerly macropeptides, 11–100 amino acids)

String type

  • linear
  • cyclical

type of bonds

  • homodet (peptide bonds only)
  • heterodet (peptide and other bonds)
    • disulfide -S-S-, ester (depsipeptides) -CO-O-R

Bound folders

  • homeomeric containing only amino acids
  • heteromeric (peptoids) containing also other compounds
    • nucleopeptides – phosphopeptides
    • lipopeptides – chromopeptides
    • glycopeptides – metallopeptides

Occurrence[edit | edit source]

  • products of metabolism, natural peptides
  • products of proteolysis, enzymatic or non-enzymatic hydrolysis
  • synthetic peptides, substitute sweeteners

Properties[edit | edit source]

  • biological activity
  • sensory properties
  • products of metabolism of lactic acid bacteria = bacteriocins
  • nisin (Streptococcus cremoris, syn. Lactococcus lactis ssp. Lactis)
  • preservative, stabilization of fermented products

Significant Peptides[edit | edit source]

Glutathione[edit | edit source]

(G-SH or G-S-S-G) γ-L-glutamyl-L-cysteinylglycine (γ-amide bond) File:Glutathione.jpg

Occurrence

  • microorganisms, plants, animals
    • wheat flour (10-15 mg/kg)
    • meat (300-1500 mg/kg)

Function

  • detoxification of toxic forms of oxygenu
  • transport (transfer) of amino acids into cells
  • metabolic processes (leukotriene biosynthesis)
  • stabilization of the oxidation state of SH-proteins (substrate of peroxidase, glutathione reductase)
  • technology


Chorleywood method of white bread production, ascorbic acid

  • H2A + ½ O2 → A + H2O (ascorbase)
  • A + 2 G-SH → H2A + G-S-S-G (glutathione dehydrogenase)
  • G-S-S-G – without affecting the rheological properties of the dough
  • G-SH – negative effect (gluten protein depolymerization)
  • P-S-S-P + G-SH → P-S-S-G + P-SH

β-alanylhistidine dipeptides[edit | edit source]

Occurrence

  • in meat

Function

  • participation in contraction of skeletal muscle
  • buffering capacity of the muscle
  • organoleptic properties

Products of proteolysis

  • spontaneous proteolysis (autolysis)
    • desired maturation of meat (consistency, aroma), production of yeast autolysates (additives)
    • undesirable
  • intentional proteolysis
    • cheese production (desired consistency, aroma)
    • production of malt (stabilization of beer foam)
    • production of protein hydrolysates
      • Enzymatic:
        • soy sauce
        • hydrolysates of waste proteins (blood, whey, caseins)
      • sour: soup spices and other preparations

Bitter peptides of enzyme hydrolysates and foods[edit | edit source]

  • hydrophobic amino acids: Val, Leu, Ile, Phe, Tyr, Trp (M < 6000 Da)

Synthetic Peptides[edit | edit source]


Links[edit | edit source]

Related Articles[edit | edit source]

Source[edit | edit source]


References[edit | edit source]