Proteins Pt 2 Flashcards
List positively charged amino acidss
Lysine, arginine and histidine
Proteins are what shaped polymers
Linear
What is an alpha helix
A coiled structure that is stabilised by intrachain hydrogen bonds
How many amino acids per turn of the helix
3.6
What percent of proteins are most soluble
25% a-helix
How are B pleated sheets made?
It is composed of two or more polypeptide sequences called b strands.
How are b pleated sheets formed?
The b-pleated sheet is formed by linking two or more strands by hydrogen bonds.
How is B pleated sheets important in many proteins,
lipid metabolism
–Immunogloblins
How do polypeptides change directions
Polypeptide chains can change direction by making reverse turns and loops
Where are turns and loops usually found?
Turns and loops are usually on the surface of the protein and participate in interactions with other molecules
What are keratins primary components of
Primary component of wool, hair and skin
What does keratin consist of
The keratin helix consists of two a-helices intertwined to form an a helical coiled coil
How is keratin stabilised
Stabilised by Van der Waals forces and ionic interactions
Van set waals forces definition
The electrons in an atom are moving around and at any given time they are unlikely to be evenly spread.
Are they stronger or weaker than covalent bonds
Weaker
What is an ionic bond
Electrostatic attraction between two oppositely charged molecules
What is a characteristic of wool
Wool can be stretched to almost twice its length breaking the weak interactions between the helices.
What amino acid is present in every 3rd residue in the sequence of collagen
Glycine
What type of bond is not in the collagen helix
Hydrogen
Functions of collagen
Fibrous structural protein
•Exists as tough bundles of collagen fibres
•It has great tensile strength.
•It is the main component of cartilage, ligaments, tendons, bone and skin.
•It acts with keratin to give skin its strength and elasticity.
Disorders associated with improper collagen
Scurvy
Blue scelera ( blue whites of the eyes)
Osteogenesis imperfecta (brittle bone disease)
Uses of collagen
Cosmetic surgery
•Burns surgery
•Casings for sausages
•Processed collagen