L 22 Protein Structure And Modfications Flashcards
What are orders of protein structure
Primary,secondary,tertiary and quaternary
How is primary structure defined
Linear sequence of amino acid residues linked to each other by peptide bonds
How is secondary structure defined
Regular recurring arrangements of adjacent amino acid residues in a polypeptide chain
How is specific structure of secondary proteins kept
By hydrogen bonds
What are the 2 main types of secondary structure and describe them
Alpha helix:rigid spiral structure consisting of tightly packed coiled polypeptide backbone core with side chain of amino acids extending outward from central axis
Beta pleated sheet: 2 or more segments of polypeptide chain line up next to each other forming sheet like structure
What is tertiary structure
3D folded and biologically active confirmation of a protein referred to as tertiary structure
How is tertiary structure stabilized
By interactions between side chains,ionic interactions,disulfide bonds and hydrogen bonds
What are domains
3D Structural part of protein that can fold function and exist independently of rest of protein chain
Some proteins have a single domain while others may have many
What is quaternary structure
Arrangement of polypeptide subunits held together by non covalent interactions (as H bonds)
Clinical implication: how can improper folding of proteins affect a person
They are tagged and degraded however they can accumulate especially in old age and can cause Parkinson’s and Alzheimer’s
What are chaperons
Family of proteins that guide proteins along proper pathways for folding shielding them from anything that might bind and hinder the process
They can be termed heat shock as they are made in large amounts when cell is exposed to heat
What is denaturation
Involves destruction of higher level structural organization of protein(secondary,tertiary)due to rupture of covalent bonds
What are causes of denaturation
Physical: high temp
Chemical: acidic or basic ph
Effects of denaturation
Loss of biological activity of protein and hormone
Changes of antigenic property of proteins
Denatured proteins are easily digested due to unfolding of peptide chains
How can perms relax hair
Denaturation of disulfide bonds in hair that are responsible for curly appearance
How are proteins classified
Chemical composition
Shape
Biological value
How are they classified based on chemical composition
Simple proteins which are only made of amino acids
Conjugated proteins which contain a non protein portion
Give examples for simple proteins
Plasma albumin which is an imp in transport protein in blood
Collagen which is a major component of connective tissue that make up tendons ligaments skin and muscles
Give examples of conjugated proteins
Glycoproteins:carbohydrate added to polypeptide backbone which plays an imp role in cell signaling,cell attachment and regulating immune system
Lipoproteins: lipids added and plasma lipoproteins play a key role in absorption and transport of lipids
How are proteins classified based on shape
Either fibrous or globular
What are fibrous proteins and give examples
Elongated strand like structures and are usually present in form of rods or wires and have only primary and secondary structure
Have mechanical and structural function
Keratin
What are globular proteins and give examples
Have compact and more or less spherical structure
Soluble in water
All structures
Myoglobin: O2 carrier in ms cells providing O2 to working muscle
Hb: responsible for transferring O2 from lungs to tissues
How can proteins be classified by biological imp
HIGH value or LOW
HIGH= meat, poultry,fish and dairy
Low= legumes and vegetables
