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Proteins
Jitka Škopová a Lenka Šibravová
Protein
(from the Greek "protas" meaning "of primary importance )
 one of the classes of biomacromolecules (alongside
polysaccharides, lipids, and
nucleic acids)
 discovered by Jöns Jakob
Berzelius (Swedish chemist) in
1838
 discovered lithium, vanadium,
silicon, selenium, thorium, and
cerium)
Proteins
characteristics
 complex, high-molecularweight organic compound
 consists of amino acids joined
by peptide bonds
 proteins are polymers, with
amino acids being the
monomers
 one of the classes of biomacromolecules
 function of all living cells and
viruses
Proteins structure
Biochemists refer to four distinct aspects
of a protein's structure:
 Primary structure
• the amino acid sequence
(the order in which the amino
acids are linked together
(specified by genetic
information)
 Secondary structure
• consists of several repeating
patterns in a part of polypeptide
chain
• contain α-helix and β-pleated
sheet
 Tertiary structure
• the overall shape of a single
protein molecule
 hydrophobic interactions
 hydrogen bonds
 disulfide bonds
 Quaternary structure
Three-dimensional structure of myoglobine
• composed of several polypeptide chains = subunits
• noncovalent :
•
• hydrophobic interactions
• salt bridges
• H-bonds
covalent:
• (S-S) forces
Functions
 many proteins are enzymes, catalyzing chemical
reactions
 regulation of cellular functions
• signal transduction
• metabolism
 control almost all the molecular processes of the body
 those molecules that do everything that happens within
us
• proteases
• glycosidases
Occurence
in the body:
• keratin, collagen, elastin and silk fibroin, blood,
muscle
 in food:
• egg, milk, cheese
plant, animal, microbial…

compound = sloučenina

joined = spojený

essential = nezbytný

polypeptide chain = polypeptidické řetězce

hydrogen bonds = vodíkové můstky

occurence = výskyt

salt bridges = sodné můstky