3.7 Types of Proteins Flashcards
What are the 2 main types of proteins?
- FIBROUS
-
GLOBULAR
- (includes conjugated proteins)
Describe the properties of globular proteins:
- WATER-SOLUBLE
- in tertiary structure, bonds form such that hydrophilic R-groups face outwards
- can interact with water solvent, ∴ water-soluble
- COMPACT & SPHERICAL
- for transport via bloodstream
Insulin is a [fibrous/globular] protein involved in…
globular
regulation of blood glucose
What is the advantage for hormones to be globular proteins?
globular proteins are soluble
∴ hormones can be transported in bloodstream
What is a prosthetic group?
non-protein component
of a conjugated protein
What is a conjugated protein?
globular protein
containing a prosthetic group
attached by covalent bonds
Name 2 examples of conjugated proteins:
HAEMOGLOBIN
CATALASE
Describe the structure & function of haemoglobin:
red, O2-carrying pigment of red blood cells
quaternary protein made from 2 beta + 2 alpha subunits
each subunit = polypeptide + Fe2+ haem group
can bind reversibly with O2, & release where required
Describe the structure & function of catalase:
enzyme, catalyses breakdown of H2O2 ⟶ O2 + H2O
quaternary protein from 4 haem groups
Fe2+ allows interaction with H2O2
prevents toxic H2O2 buildup
Describe the structure & function of catalase:
enzyme, catalyses breakdown of H2O2 ⟶ O2 + H2O
quaternary protein from 4 haem groups
Fe2+ allows interaction with H2O2
prevents toxic H2O2 buildup
What are fibrous proteins?
long, insoluble, structural proteins
Describe the properties of fibrous proteins:
- INSOLUBLE
- high proportion of hydrophobic R-groups
- STRONG
- Repetitive sequence of amino acids primary sequence
- LONG
Name 3 examples of fibrous proteins & their function:
KERATIN - present in hair, skin & nails
ELASTIN - makes up alveoli walls
COLLAGEN - connective tissue in skin, tendons, ligaments
What is the difference between a simple & conjugated protein?
Simple proteins do not contain a prosthetic group attached by covalent bonds
