Enzymes Flashcards
catalyze oxidation reduction reactions
Oxidoreductase
What are some examples of Oxioreductases?
dehydrogenases
catalyze transfer of some groups from one substrate to other
Transferases
What are some examples of transferases?
Kinases
catalyze hydrolysis reactions by adding H2O
Hydrolases
What are some examples of Hydolases?
Gastrointestinal digestive enzymes
catalyze the breakdown of compound without adding H2O
Lysases
catalyze isomerization reactions
Isomerases
What are some examples of isomerases?
Recemase or mutase
catalyze ligation reaction
Ligases
What are the ABCs that ligases need?
ATP, Biotin, CO2
What is ∆G <0?
Thermodynamically spontaneous (energy released, often irreversible)
What is ∆G >0?
thermodynamically non-spontaneous (energy required)
What is ∆G =0?
reaction at equilibrium (freely reversible)
What are three important factors that affect enzyme activity?
- substrate concentration
- temperature
- pH
What are 4 other factors that affect enzyme activity?
- Enzyme concentration itself
- product concentration
- presence of activators or inhibitors
- availability of coenzymes
What is the Michaelis-Menten equation?
V1= Vmax[S]/{Km +[S]}
What does a small/low Km represent?
high affinity of the enzyme
What are the classes of enzymes? (Think Over the HILL)
Oxidorreductase Transferases Hydrolass Isomerase Lysases Ligases
What is seen in the competitive inhibition graph?
they cross; no change in vmax, km increases
What is seen in the non-competitive inhibition graph?
they don’t cross; no change in km, vmax decreases
What is the Lineweaver-Burk equation?
1/v = [(km1/vmaxs)+ (1/vmax)]
What is the km for hexokinase?
.05mM
What is the km for glucokinase?
5mM
What do Statin drugs inhibit?
HMG-CoA reductase
Negative allosteric effectors cause what shift in the reaction curve?
Right
Enzymes following michaelis menten kinetics show what curve?
Hyperbolic
Allosteric Enzymes show what curve?
Sigmoid
What are the positive allosteric effectors of PfK-1 which shift the curve to the left?
AMP and fructose 2,6-bisphosphate
What are the negative allosteric effectors of PfK-1 which shift the curve to the right?
ATP and citrate
What is the subunit composition of LDH1?
HHHH
What is the subunit composition of LDH2?
HHHM
What is the subunit composition of LDH3?
HHMM
What is the subunit composition of LDH4?
HMMM
What is the subunit composition of LDH5?
MMMM
Where is LDH1 located?
Heart, RBC
What is the importance of LDH1?
MI
Where is LDH2 located?
Heart, RBC, kidney
What is the importance of LDH2?
Megaloblastic anemia
Where is LDH3 located?
Brain, kidney, WBC
What is the importance of LDH3?
Leukemia, malignancy
Where is LDH4 located?
Lung, muscle
What is the importance of LDH4?
Pulmonary infarction
Where is LDH5 located?
Liver, muscle
What is the importance of LDH5?
Liver disease, muscle injury
What is the subunit composition of CK1?
BB
What is the subunit composition of CK2?
MB
What is the subunit composition of CK3?
MM
Where is CK1 located?
Brain
Where is CK2 located?
Heart
Where is CK3 located?
Skeletal Muscle
What is the importance of CK1?
no clinical significance
What is the importance of CK2?
MI
What is the importance of CK3?
Muscular dystrophy
Which type of CK is the most abundant?
CK3
Which type of LDH is most abundant?
LDH2
When do CK-MB levels appear in plasma with MI?
3-6 hours following chest pain
When do CK-MB levels reach its peak of activity during an MI?
12-24 hours
When do Ck-MB levels return to baseline during an MI?
48-72 hours
When do LDH1 levels appear in plasma with MI?
48 hours following chest pain
When do LDH1 levels reach its peak of activity during an MI?
72-96 hours
When do LDH1 levels return to baseline during an MI?
10 days
When do cTI levels appear in plasma with MI?
4-8 hours following chest pain
When do cTI levels reach its peak of activity during an MI?
12-24 hours
When do cTI levels return to baseline during an MI?
7-10 days
Which test is this?
appears in plasma 3-6 hours following chest pain, reach its peak of activity at 12-24 hours, and return to baseline at 48-72 hours
CK-MB
Which test is this?
appears in plasma 48 hours following chest pain, reach its peak of activity at 72-96 hours, and return to baseline at 10 days
LDH1
Which test is this?
appears in plasma 4-8 hours following chest pain, reach its peak of activity at 12-24 hours, and return to baseline at 7-10 days
cardiac troponin (cTI)