proteins
TRANSCRIPT
Fish known as the
cheapest source of
protein as became major
part of the family
consumption in the
Philippines.
Proteins Any a large numbers of
organinc compounds thatmake up living organismsand are essential to theirfunctioning.
Are made up of aminoacids.
Amino Acids
An important class of
organic compounds thatcontain both the amino (-NH2) and carboxyl (-COOH)groups.
20 Amino Acids Alanine Glycine Serine
Arginine Histidine Threonine
Asparagine Isoleucine Tryptophan
Aspartic acid Leucine Tyrosine
Cysteine Lysine Valine
Glutamic acid Methionine Proline
Glutamine Phenylalanine
When a living cellmakes protein, thecarboxyl group of oneamino acid is linkedto the amino group ofanother to form apiptide bond.
The carboxyl groupof the second aminoacid is similarly linkedto the amino group of athird, and so on, until along cahin is produced.
This chainlike molecule, which may contain from 50 to several hundred amino acid subunits, is called a polypeptide.
A protein may be formedof a single polypetidechain, or it may consistof several such chainheld together by weakmolecular bonds.
Bonds of Proteins
The primary (1° ) structure of a protein is simply the sequence of the amino acids.
Lys-glu-pro-leu- and so on.
The secondary (2° ) structure of a protein is the
interactions between portions of the peptide chain. Hydrogen bonding is one such
interaction that leads to a helix, b sheet and triple
helix structures.
The tertiary (3°) structure of a protein can be thought of as
its three dimensional structure. The
tertiary structure involves the
overlapping or folding of a peptide upon
itself.
A protein has quaternary (4°)
structure if two or more polypeptides interact
with one another to from a biologically active
protein.
Each protein is formed according to a
precise set of instructions
contained within the nucleic acid, which is the genetic material
of the cell.
These instructions determine which of the
20 standards amino acids are to be incorporated into the protein, and in
what sequence.
E.g. Keratin (hair,skin, and nails)
Collagen (bone, tendon and cartilage)
Elastin (elastic fibers of connective tissue)
Conjugated proteins
Prosthetic group1. Phosphoproteins - e.g.
casein
2. Glycoproteins - e.g. mucin
3. Nucleoprotein
4. Lipoproteis - compound lipids
5. Chromoprotein –pigmented prothetic group e.g hemoglobin (with iron – containing pigment, heme) coordinated to a simple protein portion, globin.
Accrdg. to function
1.Structural proteins– more than half ofthe total protein ofthe mammalian bodyis collagen, found inskin, cartillage andbone.
3. Enzymes- these biological catalysts are vitally important to all living systems.
4. Hormones- e.g. insulins
5. Antibodies
the body producesantibodies to destroyany foreign materials(antigens) releasedinto the body by aninfectious agent.
6. Blood proteins
the albumins, globulins and fibrinogen are the three major protein constituents of the blood.
Biogenic amines-are volatile amines
that are produced as a result of the breakdown of amino acids, typically on death of the animal.
Protein Denaturation
Any change the secondaryand tertiary structure ofprotein without causing aconcomitant cleavage ofthe peptide bonds.