lecture 20 - tertiary & quaternary structure Flashcards
explain the tertiary structure
the folded, functional structure of a protein
what is the tertiary structure stabilized by? are these interactions weak or strong?
- long-range non-covalent interactions
- weak
define “long-range” interactions
far apart in amino acid sequence
teritary structures can be composed of? (2)
motifs or domains
what are the specific forces that stabilize tertiary structure?
- the hydrophobic effect
- h-bonds
- electrostatic interactions
- disulphide bonds
explain the role of disulphide bonds with respect to tertiary protein structure
- disulphide bonds form in oxidizing environments (outside cells)
- provide extra stabilization in harsh environments
- only form after protein is folded & thus do not help the folding process
define domains
discrete regions of sequence that fold up into a single 3D structure
explain globular protein structure and describe their domains.
- single folded entity
- domains are in tight contact
explain multimodular proteins and describe their domains.
-domains are linked by flexible linker regions
(appear as beads on a string)
-contain independently folded units
-domains may have multiple distinct and complimentary functions (for e.g. enzymatic, carbohydrate and scaffold domains)
-creates functional synergy and functional cooperativity
define quaternary structure and the forces that stabilize it
- multiple polypeptides (that make up the protein)
- often interact via non-covalent interactions
- may be linked by disulphide bonds in extracellular proteins
define homomultimers
-proteins with idintical subunits
-can have homodimers or homotrimers
(A-A)
define heterodimers
-proteins with different subunits
A-B
explain the structure of hemoglobin
appears as a dimer of alpha and beta heterodimers
list the 3 kinds of protein folds
(1) fibrous proteins
(2) globular proteins
(3) intrinsically disordered proteins
