Proteins Flashcards
Oligopeptides
Polypeptides
Proteins
2-10
11-49
50 or more
Proteins arrangement
Head to tail
N terminus to C terminus
Primary structure is….held together by …
The…is …to the protein
Number and sequence of a minor acids in the polypeptide chain
Peptide bonds
Sequence of amino acids /specific
Collagen has which structure
None, it has a unique structure to it
Native proteins
Newly synthesised proteins ready to work after Golgi modification
Do fibrous proteins have a tertiary structure
Examples
No
Collagen, elastin, keratin
Many poly peptides n to c
Many n to c and c to n
Parallel
Antiparallel
A change in a single amino acid may cause
Profound physiological effects
2 main forms of 2ndry structure
A - helical>folding on its axis, stabilized with hydrogen bonds
B pleated sheets> extended chain hydrogen bonds
A-helical must have…..only
Has …..only
While b pleated sheets have…..and……and….
1 chain
Intra chain bonds
2-5 chains
Inter and intra chain bonds
R groups of amino acids……. In a-helix
Project outwards
Other forms of 2ndry structure
Loop regions
b bends
Disordered regions
Tertiary and quaternary
Folding into 3D shape, globular proteins only, all bonds
If more than 1 polypeptides enter quaternary structure as well
The bonds 6
Peptide> condensation between 2 amino acids
Van der waals>weak interactions
Disulfide> proteins with sulfur, 2 cysteine
Hydrogen>polar side group with water or other polar group
Ionic bonds>NH3+ and COO-
Hydrophobic interactions>non polar R groups
Hydrophobic interactions present
In the interior side of the protein
Example of a protein with disulfide bonds
Insulin
Chaperons
Group of molecular proteins that ensure efficient protein folding and prevent aggregation.
*With age chaperons decline causing aggregation and alzheimer’s ,parkinsons, and neurodegenerative diseases.
Causes of denaturation
Physical>heat/mechanical agitation/UV
Chemical>acids/alkalis/salts of heavy metals
After denaturation ….remains
Primary structure
Heat coagulation test
Albumin coagulation due to heat that causes disulfide cross linakge
Effects of denaturation
Loss of structure
Loss of biological activity
Loss of antigenic property
Less soluble
High digestibility
High viscousity
Why higher digestiability
Due to the projection of peptide bonds which will be digested by proteolytic enzymes
Gluten is
Scleroproteins are
Both are…that yield….only
Gliadins and glutelins
Supportive proteins as elastin and keratin
Simple proteins
Amino acids
Types of complex proteins
phosphoproteins>phosphate connected to OH of serine/threonin/tyrosine> casein of milk
Lipoproteins
Metalloproteins
nucleoproteins> basic protein+RNA/DNA» histones
Chromoproteins
Glycoproteins
Glycoproteins have less…and more..
2 types
Examples
Carb, protein
N linked, O linked
Amide group of asparagine,, hydroxyl group of serine/threonine
Either with carb radical
Chromoproteins
Pigmented group either…or…
Metallochromoprotein> iron=red/copper= green blue
No metallochromoprotein > flavo proteins(yellow) D and L amino acid oxidases / melanoproteins(brown/black) like melanokeratin
Metallo proteins
Heme iron
Non heme iron
Copper
Magnesium
Manganese
Zinc
Hemoglobin,myoglobin
Ferritin(iron storage),transferritin(iron movement)
Superoxidase dismutase/ cytochrome oxidase
Kinases
Arginase
Storage form of insulin/ carbonic anhydrase enzyme
Lipoproteins
With triacylglycerols and or other lipids(phospholipids/ cholesterol)
Movement of lipids in blood
Protein degradation
Lysosomal>long half life, digest endocytosed proteins
ATP dependent proteosomal degredation>short half life/abnormal>multistep requiring ubiquitin
Half life of a protein is determined by
R group of amino acids
