FINAL - CH 6 Flashcards
Protein Classifications by Function
metabolic enzymes structural proteins transport proteins cell signaling proteins genomic caretaker proteins
Examples of Structural Proteins
Actin
Tubulin
Collagen
Energy in active transport comes from
either:
ATP hydrolysis
Ionic gradient
Membrane receptors
G-protein coupled receptors (GPCR)
Receptor tyrosine kinases
Genomic caretakers
DNA polymerase
DNA ligase
Topoisomerase
DNA primase
Photolyase
uses DNA template to guide synthesis of nascent DNA strands
DNA polymerase
Seals newly formed DNA
DNA ligase
assist DNA polymerase by preparing the DNA template for replication
DNA primase
repairs thymine dimers that are formed as a result of UV radiation
Photolyase
Heme is a ________ complex
Fe2+ -porphyrin
Oxygen only binds to the prosthetic group with iron in its
_______
reduced state, ferrous state
Myoglobin is composed of ________
8 alpha helices
AAs involved in prosthetic group
His E7
Vall E11 Phe CD1
His F8
His E7 binds to:
Oxygen with a hydrogen bond
His F8 binds to:
Iron
His E7 is the _____ histidine
Distal
His F8 is the _____ histidine
Proximal
Are hemoglobin subunits bound covalently or not?
Not
When oxygen is unbound:
Heme group is puckered
When oxygen binds:
Heme group is planar and F helix is moved closer to plane
T -> R Transition involves:
breakage and reformation of many noncovalent interactions between
____ are released during the T -> R Transition
Protons
As one O2 binds:
the subunits change conformation, increasing the likelihood of additional O2 binding
binding of a ligand at one site affects the binding of
another ligand at another site
Allosteric effects
All the subunits must be in either T or R
form, model does not allow combinations
of T and R state.
Concerted Model of Allosterism
Ligand binding progressively induces
conformational changes in the subunits
Sequential Model of Allosterism
α1β1 has ____ residues that interact
35
α2β2 has ____ residues that interact
19
α-β interactions are mostly:
hydrophobic
H bonds
Ion pairs
Solvent f channel ______ when O2 binds
Narrows
How does Solvent f channel narrow:
α-β complexes shift by 15 degrees bringing β subunits closer together
Helix F tilts and translates by _____
1 angstrom
In the T state Fe is _____ out of the plane
0.6 angstroms
