81017
Description
Flashcards by sophiakostich, updated more than 1 year ago
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Created by sophiakostich
over 11 years ago
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| Question | Answer |
| What is the Michaelis-Menten model for enzyme kinetics? |
Image:
Eqn003.gif (image/gif)
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| What is Kcat a measure of? | Kcat is a measure of catalytic production of product under optimum conditions (saturated enzyme). |
| What are the units of Kcat? | s-1/generally time |
| What is the equation for Kcat? | |
| What is Vmax? | Vmax is when 100% of enzyme is complexes with substrate - the maximum rate at which the reaction between enzyme and substrate can occur. |
| Draw a Michaelis-Menten plot of v versus [S]. | |
| What is the Michaelis Menten equation? What do all the parts of it stand for? | V= velocity, Vmax = theoretical maximal velocity, [S] = substrate conc, Km = constant for any enzyme V=Vmax x [S]/Km + [S] |
| Which has a higher affinity for substrate binding? High or low Km? | High Km - low affinity of enzyme for substrate Low Km - high affinity of enzyme for substrate (therefore low Km means better reaction) |
| What does Km equal on the michaelis-menten graph? | Km = 1/2 Vmax... Km = [S] |
| What are the units for Km? | As Km=[S] they are the same as whatever the units are for [S] in the given reaction. |
| Draw a Lineweaver-Burk Double Reciprocal plot. | |
| What is a competitive inhibitor? How can it be overcome? | A competitive inhibitor competes with substrate to bind active sites and reduces the proportion of enzymes bound to substrate. It can be overcome by increasing the concentration of substrate. |
| What is a non-competitive inhibitor? How can it be overcome? | A non-competitive inhibitor inactivates some of the enzymes so it can no longer bind substrate resulting in decreased turnover number. Non competitive inhibition cannot be overcome. |
| How does the Lineweaver burk plot change with competitive and non-competitive inhibitors? | |
| What is Ki? | Relationship between an enzyme and the inhibitor. |
| What factor is the slope of a lineweaver-burk plot increased by in presence of competitive inhibitor? | By a factor of (1 + [I]/Ki) where [I] is the concentration of the inhibitor and Ki is the dissociation constant of the EI complex. |
| Does low Ki indicate strong or weak enzyme binding? | Low Ki indicates strong binding (like Km). |
| What happens to Vmax and Km in the presence of a non-competitive inhibitor? | Vmax decreases whilst Km stays the same. |
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