Week 4 Flashcards
Competitive Inhibitor
Vmax same, change in Km
Uncompetitive Inhibitor
Change in Vmax and Km
NonCompetitive Inhibitor
Change in Vmax, same KM
Kd Equation
(Mb)(O2)/(MbO2)
Kd Definition
Smaller Kd the greater affinity of the ligand for its protein. Dissociation
Myoglobin
Higher affinity for oxygen
Acts as oxygen storage in tissue
Hemoglobin
Acts as oxygen transporter through bliss
Exhibits cooperatively
Has quarternary structure
Effects on Hb
Positive: CO and O2
Negative: 2,3 BPG, CO2, H+
Bohr Effect
Concentration of CO2 increases, H+ ions increase
Oxygen binding curve for fetal Hb lays where
To the left of
Reversible Inhibitors
Competitive, Uncompetitive, and NonCompetitive
Irreversible Inhibitors
Bind very tightly to active site
No products formed, shuts enzyme down
Powerful tools for elucidating the mechanisms of enzyme action
Catalytic Triad
Asp, His, and Ser
What stabilizes polypeptide
Oxyanion Hold
Chymotrypsin Mechanism Steps
- His extract H+ from Ser
- Ser attacks peptide
- Formation of Tetrahedral Intermediate
- Tetrahedral Intermediate extracts H+ from His
- Cleaved peptide 1 is free to leave
- Cleaved peptide leaves and is replaced with water
- Hid extracts H+ from water, OH attacks peptide bound to Ser.
- H+ is extracted from His
- Peptide 2 is free to leave
Oxyanion Hole
Hydrogen bonding with backbone of peptide chain
Heme
Prosthetic Group
How is iron held
Iron is held in gene group by 6 coordinate covalent bonds from the 4 nitrogen’s in tetra pyrrole group
How many coordination sites does iron give
6
4 are occupied by nitrogen’s in tetrapyrrole ring
5th is nitrogen from proximal histidine
6th is occupied by O2
Fractional Saturation Equation, Y
Y = pO2/Kd + pO2
@ Y=1/2 Kd=O2
Oxygen Binding with Iron
No O2 bound iron is larger than bound O2
Bohr Effect
Stimulation of O2 release by CO2 and H+
Shift Right
Negative Effect
Shift Left
Positive Effect
