BIOCHEM TEST 3
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What is a Cofactor?
A non protein group associated with a protein.
What are the two main types of Cofactors?
- Coenzymes- Organic
- Essential Ions- Inorganic
What are the two types of Coenzymes?
- Cosubstrates-Easy to remove
- Prosthetic Group -Large/difficult to remove without denaturing the protein.
What is myoglobin?
A single polypeptide chain conjugated with Heme. It binds to and STORES oxygen in Muscle tissue.
Which mammals would be expected to hold large reserves of myoglobin?
Deep sea divers (those who will be underwater without O2 for long portions of time)
What is hemoglobin?
- A protein tetramer (has quaternary structure)
- Conjugated protein with one Heme per subunit.
- Binds to and TRANSPORTS oxygen.
What are the two forms of iron, and what hemoglobin do they give?
- Ferric- +3 (Met Hemoglobin)
- Ferrous- +2 (Normal)
Which cavity is larger, deoxygenated or oxygenated hemoglobin?
Does Met Hemoglobin bind oxygen?
How many bonds surround the ferrous iron in hemoglobin? What shape is this structure?
Why is Carbon Monoxide so dangerous?
It can bind to the same spot as O2 in hemoglobin, and make that hemoglobin unable to transport oxygen.
If hemoglobin has been bound to CO, what color is it?
even brighter red!
What is the role of the proximal histidine in hemoglobin?
To anchor the heme.
How does oxygen cause the cavity of hemoglobin to shrink?
the oxygen pulls the fe into line with the heme ring, causing a tilt in the polypeptide.
What are the two different states of most hemoglobin?
What is the equation for the Allosterism of Hb?
4O2R <---> T + 4 O2
What hemoglobin can be found in those with diabetes?
Hb A1c. Binds glucose to hemoglobin.
Name the 6 classes of Enzymes
What do Oxidoreductase enzymes do?
Catalyze redox rxns
What do transferase enzymes do?
Catalyze group transfer rxns
What do hydrolase enzymes do?
Catalyze hydrolysis of bonds by water
What do lysase enzymes do?
Split a substrate, creating a double bond
What do isomerase enzymes do?
Move a functional group within a molecule
What do ligase enzymes do?
Catalyze the joining of two substrates and require energy input.
Name one example of a oxireductase enzyme, and its function.
- Lactate Hydrogenase
- Reduces Lactate to Pyruvate. (Loss of 2 H's)
Name one example of a Transferase enzyme and its function.
- Alanine Trasaminease.
- Converts alanine and ketogluterate into pyruvate. Needed when glucose is not around.
Name one example of a hydrolase enzyme and its function.
- Cleaves pyrophosphotase into 2 phosphates.
Name one example of a Lyase and its function.
- Pyruvate decarboxylase
- Converst Pyruvate into acetaldehyde and CO2
Name one example of a isomerase and its function.
- Converts glucose 1 phosphate to glucose 6 phosphate
Name one example of a ligase and its function.
- Glutamine sythetase
- Converts glutamate into glutamine.
What is the initial rate of a rxn a calculation of?
Slope of the first tangent line.
What is the general equilibrium equation in Biochemistry?
- S ----> P
When is maximum velocity of a reaction achieved?
When Total E compound = ES.
What does Vo equal?
What does the Steady State Assumption all us to assume?
Rate of Formation of ES= Rate of Breakdown. This allows us to derive the Michaelis Menten constant Km.
What is Km?
- Michaelis Menten Constant
- k-1 + k2/k1
[E][S]/[ES] = Affinity for a substrate. Low Km = High Affinity.
K=[S] that provides half the maximal rate for the reaction.
As Concentration of [S] increases, what does its order become?
Goes from First order to Zero Order.
Which enzyme, hexokinase (muscles) or glucokinase (liver), has a higher affinity for glucose?
What is the lineweaver burk equation?
Inverse the Michaelis & Menten equation, and seperate the terms into a line equation y=mx+b
1/vo= km/vmax * 1/[s] + 1/vmax
What is the Michaelis Menten Equation?
In lineweaver burk graphs, what is the x intercept?
What are the 3 categories of non covalent reversible inhibitors of M-M Enzymes
Competitive, Non Competitive, Uncompetitive.
What do competitive inhibitors bind to?
Which compounds can stop Folic Acid Synthesis?
Sulfonamides bind to hihydropteroate sythetase.
How do competitive inhibitors change the slope on a Lineweaver burk graph?
- Increases slope by increasing Km
What do uncompetitive inhibitors bind to?
How do uncompetitive inhibitors affect Lineweaver-Burk graph?
THey change the Y & X intercept.
Lowers Vmax AND Km, but keeps the same ratio (slope remains the same.
What do noncompetitive inhibitors bind to?
Either E or ES compounds.
What does Noncompetitive Inhibitors do to a Lineweaver-Burk Graph?
Changes the slope by Lowering the VMax
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