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PROTEINS
Proteins are complex biomolecules that
contain amino acids linked through
peptide bonds.
Molecular weight : 6,000 to over 1,000,000
Considered as the most versatile biomolecules
Serve numerous essential functions in biological
processes
Primary constituents of living organisms
Contain NITROGEN (N) aside from C, H and O
Foods rich in proteins: animal meat, tuna, cheese,
tofu, beans
Proteins are complex biomolecules
that contain amino acids linked
through peptide bonds.
derived from the Greek word “Proteios” – of first importance
Two Major Types of Proteins:
1) Fibrous proteins (collagen, actin, keratin)
- insoluble in water; main components of the body
2) Globular proteins (albumin, hemoglobin, and
immunoglobulins)
- soluble in water; used for the other non-structural
purposes of proteins.
Proteins play a wide variety of functional
roles.
STRUCTURE: form the scaffolding that gives animal cells their shape. (skin, bones, hair, nails); Collagen & Keratin
HORMONES: Insulin helps cells absorb glucose from the blood & helps the body from using fat as a source of energy
TRANSPORT: Hemoglobin; involve in the transport of molecules across cell membranes
Proteins play a wide variety of
functional roles.
STORAGE: Casein (milk) stores nutrients for newborn mammalsFerritin, blood cell protein in the liver, stores iron
CATALYST: Enzymes (protein that speeds up all the reactionthat take place in organisms)
PROTECTION: antibodies to counteract & fight disease ; Fibrinogen = facilitates blood clotting
Proteins play a wide variety of functional
roles.
MOVEMENT: protein in muscles (myosin & actin) –
muscle contraction and relaxation
REGULATION: control & regulate the kind of protein
synthesized in a particular cell but also dictate the
time this should occur
Amino acids are the building blocks of
protein.
Composition: Central C bonded
to H, a carboxyl group (-
COOH), an amino group (-NH2)
and a side chain (R group)
Total amino acids: 20
The R group is the one that is
variable among the 20 amino
acids.
THE TWENTY AMINO ACIDS (*essential cannot be produced by the body)
Amino Acid Abbreviatio
ns
Side chain/R group Linear Formula
Alanine Ala A CH3-CH(NH2)-COOH
*Arginine(essential amino
acid)
Arg R HN=C(NH2)-NH-
(CH2)3-CH(NH2)-COOH
*Asparagine(essential amino
acid)
Asn N H2N-CO-CH2-CH(NH2)-COOH
Source: http://www.imgt.org/IMGTeducation/Aide-memoire/_UK/aminoacids/formuleAA/#formula
THE TWENTY AMINO ACIDS
Amino Acid Abbreviatio
ns
Side chain/R group Linear Formula
Aspartic
acid
Asp D HOOC-CH2-
CH(NH2)-COOH
Cysteine Cys C HS-CH2-CH(NH2)-
COOH
Glutamine Gln Q H2N-CO-(CH2)2-
CH(NH2)-COOH
Source: http://www.imgt.org/IMGTeducation/Aide-memoire/_UK/aminoacids/formuleAA/#formula
THE TWENTY AMINO ACIDS
Amino Acid Abbreviatio
ns
Side chain/R group Linear Formula
Glutamic
acid
Glu E HOOC-(CH2)2-CH(NH2)-COOH
Glycine Gly G NH2-CH2-COOH
*Histidine(essential amino
acid)
His H NH-CH=N-CH=C-
CH2-CH(NH2)-COOH
Source: http://www.imgt.org/IMGTeducation/Aide-memoire/_UK/aminoacids/formuleAA/#formula
THE TWENTY AMINO ACIDS
Amino Acid Abbreviatio
ns
Side chain/R group Linear Formula
*Isoleucine(essential amino
acid)
Ile I CH3-CH2-CH(CH3)-CH(NH2)-COOH
*Leucine(essential amino
acid)
Leu L (CH3)2-CH-CH2-CH(NH2)-COOH
*Lysine(essential amino
acid)
Lys K H2N-(CH2)4-CH(NH2)-COOH
Source: http://www.imgt.org/IMGTeducation/Aide-memoire/_UK/aminoacids/formuleAA/#formula
THE TWENTY AMINO ACIDS
Amino Acid Abbreviatio
ns
Side chain/R group Linear Formula
*Methionine(essential amino
acid)
Met M CH3-S-(CH2)2-
CH(NH2)-COOH
*Phenylalani
ne
(essential
amino acid)
Ph
e
F Ph-CH2-CH(NH2)-
COOH
Proline Pro P NH-(CH2)3-CH-
COOH
Source: http://www.imgt.org/IMGTeducation/Aide-memoire/_UK/aminoacids/formuleAA/#formula
THE TWENTY AMINO ACIDS
Amino Acid Abbreviatio
ns
Side chain/R group Linear Formula
Serine Ser S HO-CH2-CH(NH2)-
COOH
*Threonin
e(essential amino
acid)
Thr T CH3-CH(OH)-
CH(NH2)-COOH
Tyrptophan(essential amino
acid)
Trp W Ph-NH-CH=C-CH2-
CH(NH2)-COOH
Source: http://www.imgt.org/IMGTeducation/Aide-memoire/_UK/aminoacids/formuleAA/#formula
THE TWENTY AMINO ACIDS
Amino Acid Abbreviatio
ns
Side chain/R group Linear Formula
Tyrosine Tyr Y HO-Ph-CH2-CH(NH2)-COOH
*Valine(essential amino
acid)
Val V (CH3)2-CH-CH(NH2)-COOH
Source: http://www.imgt.org/IMGTeducation/Aide-memoire/_UK/aminoacids/formuleAA/#formula
Proteins have four levels of
structure.
Depends on the sequence of the amino acids
According to complexity: Primary, Secondary, Tertiary & Quaternary
Proteins have four levels of
structure.
Proteins have four levels of
structure.
PRIMARY Structure
Linear sequence of amino
acids
Refers to the arrangement
or order of amino acids in
the protein chain
Proteins have four levels of
structure.
DIPEPTIDE
Formed when two amino acids combine through a condensation reaction
Proteins have four
levels of structure.
SECONDARY Structure
Refers to the spatial arrangement of the polypeptide chain of a protein
2 types: Alpha Helix & Beta Pleated Sheets
Proteins have four levels of
structure.
SECONDARY Structure
Alpha Helix = held
together by H bonds
between loops of a coil
Beta Pleated Sheets =
chains held together by
H bonds between
adjacent chains
Proteins have four levels of
structure.
TERTIARY Structure
Refers to the FINAL three-
dimensional shape of a
single polypeptide
molecule where the alpha
helix and the pleated
sheet are folded forming a
GLOBULAR PROTEIN.
Proteins have four levels of
structure.
TERTIARY Structure
Types of
INTERmolecular bonds:
H-bond, Dipole-dipole,
and London dispersion
Types of
INTRAmolecular
bonds: ionic &
covalent (disulphide
bond)
Proteins have four levels of
structure.
QUARTERNARY Structure
Contains more than one chain
Refers to the overall shape when 2 or more polypeptides bind each other
Results in the classification of proteins: fibrous, globular, or conjugated
Ex: Hemoglobin
Proteins denaturation involves the disruption and
possible destruction of the secondary and tertiary
structures of protein.
Proteins denaturation can be caused by several
factors.
pH changes – alter the IM; some functional groups of amino acids lose or gain electrostatic charge which affects the formation of bonds
Increase in Temperature –disrupt H bonds & nonpolar hydrophobic interactions
Proteins denaturation can be caused by several
factors.
Addition of various chemicals – destroy
the natural structure of
a protein
Ex. Addition of Urea (forms
H bonds with different
parts of the protein s
such as peptide groups
causing the weakening
of IMF)
PROTEINS
are made up of
AMINO ACIDS
Structural
Levels:
Primary
Secondary
Tertiary
Quarternary
May be denatured through:
pH changes
Temperature changes
Addition of Chemicals
Recommended