Amino Acids + Proteins Flashcards
What are Proteins?
- Linear polymers of amino acids.
Amino Acids (Read)
- 20 diff common AA
- 10 essential
- 10 non - essential
- Conc of free AA in cell is low.
Can amino acids be stored in the body?
- No
What are Amino Acids needed for?
- To meet the body’s requirement for protein.
- Synthesize new proteins
synthesis as precursors for other compounds.
What can the bacteria E.coli do?
- Synthesize a set of standard AA.
- How does the body convert proteins to AA’s in the digestive system?
- By releasing proteolytic enzymes.
What does the basic structure of an Amino Acid contain?
C.A.H.R
- Carboxyl Group
- Amino Group
- Hydrogen atom
- Side Chain ( R group)
All are attached to a central carbon atom known as the α-carbon.
How does the R Group (side chain) vary?
- Size
- Shape
- Charge
- Solubility
The properties of the side chain(s) influence the overall 3D shape (configuration of a protein). The 3 D shape plays an integral part in protein functionality.
What can the R Group (side chain) be?
▪ Aliphatic (non-polar) ▪ Aromatic (ring structure, generally non-polar) ▪ Polar ▪ Negatively charged ▪ Positively charged
What is an Aromatic Compound?
- An organic compound made of C + H, contains an aromatic ring configuration of atoms.
Give an example of an Aromatic compound.
- Benzene
What is an Aliphatic Compound?
- An organic compound made of C + H, it is Non- Aromatic.
Give examples of Aromatic Amino Acids. (P.T.T)
- Tyrosine
- Tryptophan
- Phenylalanine
How do you test for the detection of proteins?
- Spectrophotometry @ λ max 280
What is a Peptide?
- Short chain of AA monomer.
- Linked by peptide bonds
- 2 - 20 AA’s
Shortest peptide is a dipeptide, then tripeptide, tetrapeptide etc.
What are Peptide bonds also called?
- Amide Bonds
What is a Polypeptide?
- Long, continuous, unbranched peptide chain
- 20 - 50 AA’S
What is a protein?
- One or more polypeptides arranged in a biologically functional way.
- 50 - ? AA’s
How are Amino Acids added added to a linear polymer in a stepwise manner?
- By a Condensation Rxn ( loss of H2O).
Read
▪ As H2O is removed, the carboxyl
carbon of one AA and the amino nitrogen of a second are linked directly.
▪ This covalent C—N bond linking two AA’s is known as a peptide bond, shown below in bold.
▪ Formation consumes energy – living systems – ATP.
▪ Bond can be broken by hydrolysis (the adding of water) which releases
energy.
Give 5 examples of the biological functions of Peptides. ( V.O.L.A.B)
- Vasopressin (H20 Reabsorption)
- Oxytocin ( Uterine Contraction)
- LHRH (Fertility)
- Angiotensin II (Reg. Blood Pressure)
- Bradykinin ( Inhibits Inflammation)
How are Amino Acids linked?
- Covalently linked by peptide bond
- Linear sequence
How many levels of structure do proteins have?
Name these levels.
- 4
- Primary
- Secondary
- Tertiary
- Quaternary
What is the primary structure of a protein?
- The linear sequence of amino acids within a protein.
- Dictated by the Genetic Code.
What is the Secondary Structure of a protein?
- Occurs due to Hydrogen Bonding between peptide bonds along the length of the protein.
- Causing a Localized Helix to form + sheet structure.
What do hydrogen bonds do to the secondary protein structure?
- They stabilize the structure.
What is the Tertiary structure of a protein?
- Caused from extensive folding a polypeptide chain into a closely packed (almost) spherical shape.
What is the extensive folding in the tertiary structure caused by?
- Chemical interactions between the side chains of the amino acids.
What is the most protein structure/Conformation and why?
- Tertiary Structure
- Bc of the chemical interactions between the side chains of the amino acids stabilize the structure.
Read
▪ H bonding between side chains
▪ Ionic bonding between side chains with ionizable groups.
▪ Disulphide bonds between 2 cysteine residues (Cys - S - S - Cys)
▪ Hydrophobic interactions ; this is
the most significant tertiary structure stabilization force. It constitutes a non covalent interaction between the non
polar R Groups.
Quaternary structure?
▪ Limited to proteins with multiple
polypeptide sub units . Each sub unit is a separate polypeptide chain.
▪ The bonds and forces that maintain
quaternary structure are the same
as those responsible for tertiary
structure.
Give an example of a protein with a Quaternary structure?
- Hemoglobin, the oxygen carrying
protein in blood.
Biological Functions of Proteins.
- Enzymes - many proteins function as enzymes i.e. biochemical catalysts.
- Hormones; many regulate biological/biochemical functions in target tissue e.g. hormones.
- Some bind other molecules for storage and transport e.g. hemoglobin binds 0 2 , CO 2 in erythrocyte cells (red blood cells).
- Structural proteins provide support and shape to cells & therefore to tissue and organisms (skin, tendons, hair (Elastin, Collagen , Keratin).
- Assemblies of proteins perform mechanical work ( flagella, cilia , Some proteins are hormones they regulate biochemical activities in target cells or tissue.
- Proteins also serve a range of other specialized functions including their defense functions as immunoglobulin (antibodies).
Industrial Uses of Proteins.
- Enzymes: (proteases) meat tenderization, cheese manufacture rennin, contact lens cleaner.
- Regulatory Protein medical uses, insulin diabetes, growth hormone treat dwarfism, FSH treat infertility.
- Antibodies covid 19 test, HIV test, pregnancy test, Ovulation test.
