PROTEINS
by Radek Marták & Jiří Malina
Main characteristics
Word protein = form Greek Protas
(Meaning of primary importance)
Protein is a complex, high-molecular
weight organic compound, that consists of
amino acids joined by peptide bonds.
Proteins were discovered by Jöns Jakob
Berzelius in 1838.
Structure
Proteins are biopolymers build from 20
basic L-apha amino acids.
Structure of amino acids is responsible for
determining the final three-dimensional
configuration of each protein.
We define primary, secondary, tertiary and
quarternary structure.
Overview of amino acids
Primary structure
Is given by sequence of amino acids.
20 amino acids gives us about (common
protein = about 100 amino acids): 20100 =
1,27.10130 polypeptides
Secondary structure
Highly patterned sub-structures — alpha
helix and beta sheet — or segments of
chain that assume no stable shape and
are formed by hydrogen bonding.
Secondary structures are locally defined,
meaning that there can be many different
secondary motifs present in one single
protein molecule.
Secondary structure
Tertiary structure
Unique three-dimensional conformation
that globular proteins assume as a
consequence of the non-covalent
interactions between the side chains in
their primary structure
primarily formed by hydrophobic
interactions, but hydrogen bonds, ionic
interactions, and disulfide bonds are
usually involved too.
Tertiary structure
Quarternary structure
the shape or structure that results from the
union of more than one protein molecule,
usually called protein subunits in this
context, which function as part of the
larger assembly or protein complex.
Quarternary structure
Function
Structural proteins
Transport and storage proteins
Immune response proteins
Signaling and regulatory proteins
Proteins involved in cell movement
Proteins involved in platellet aggregation
Structural proteins
Structural proteins typically contain high
proportions of regular secondary structures such
as α-helix or β-pleated sheet
As a consequence of their rodlike or sheetlike
shapes, these proteins exhibit fibrous character
and have structural rather than dynamic roles
Examples of fibrous proteins include keratin
(horn, nail), collagen (skin, bones, tendones),
elastin and silk fibroin
Transport and storage proteins
Storage of amino acids and other
important substances
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Ovalbumin (egg)
Casein (milk)
Legumin (legumes)
Gliadin, zein (corn)
Ferritin (storage of Fe in )
Transport proteins
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Serum albumin – an universal transport protein
Hemoglobin (oxygen-binding protein - circulation)
Myoglobin (oxygen-binding protein - muscles)
Transferrin (transport of Fe)
Immune response proteins
Antibody molecules are produced in response to
invasion by foreing compounds that can be
proteins, carbohydrate polymers, and nucleic
acids
All antibodies have a similar structure
Immunization – vaccine consists of killed
bacterial cells, inactivates viruses, killed
parasites, a nonvirulent form of live bacterium, a
denaturated bacterial toxin or recombinnt protein
Benefits in the diet
Protein is important to the human diet, supplying
the body's needs for nitrogen and amino acids,
the building blocks of proteins.
Mammals cannot synthesize all 20 amino acids,
so protein from the diet is necessary for life and
the amino acids that cannot be synthesized by
the body are known as essential amino acids.
The exact amount of dietary protein needed for
life may vary widely depending on age, sex,
level of physical activity, and medical condition.
Protein deficiency
Protein deficiency can lead to symptoms
such as fatigue, insulin resistance, hair
loss, loss of hair pigment, loss of muscle
mass, low body temperature, hormonal
irregularities, as well as loss of skin
elasticity.
Severe protein deficiency, encountered
only in times of famine, is fatal, due to the
lack of material for the body to facilitate as
energy.
Potential risks
Overreaction within the immune system
Liver dysfunction due to increased toxic
residues
Loss of bone density (calcium and
glutamine is being leached from bone and
muscle tissue to balance increased acid
intake from diet (blood pH is maintained at
around 7.4)
Vocabulary
Tendone – šlacha
Horn – roh (zvířecí)
Nail – nehet
Vaccine – vakcína
Antibody – protilátka
Legumes – luskoviny
Vary – měnit se
Medical – zdravotní
Mammals - savci
Lack – nedostatek
Famine – hladomor
Facilitate – usnadněný
Fatique – únava, vyčerpanost
Leached – „vyluhovaný“, (=vyčerpaný z kostí)
Thanx for your attention!! Bye.
And last small easy picture of protein for you 