biochem 2 Flashcards
Four main features of Enzymes
catalysts
efficient
specific
potent
Enzymes are catalysts that increase the reaction rate by reducing __________?
activation energy
Examples of enzymes functioning as catalysts
Globular proteins
RNA (ribozymes)
At what rate are enzymes faster than a regular reaction
10^3 to 10^17
T/F Enzymes have side reactions
FALSE
T/F Enzymes do not alter equilibrium
TRUE
Enzymes are specific in the sense that they have a limited range of ___________ to produce ______________ products
substrates/ specific
Example of the potency of enzymes: carbonic anhydrase produces ________/ sec from bicarbonate
1,000,000
Enzymes lower _____________ energy
activation
Enzymes have no effect on __________________ of the reaction
overall energy change
With an enzyme what increases and what remains the same
reaction rate increases
equilibrium constant remains the same
T/F enzymes can catalyze a reaction even when it is unfavorable
FALSE
Enzymes act to _______ the activation energy and ________ the transition state
lower/ stabilize
when delta G is < 0 the reaction is
favorable
when delta G is > 0 the reaction is
unfavorable
when delta G = 0 the reaction is
at equilibrium
T/F if one reaction is not favorable but has a product that participates in a favorable reaction, the reactions can be linked together to force the original reaction to completion
TRUE
Cofactors are
non amino acid components that provide a reaction with chemistry that the R group cannot
Co-factors and prosthetic groups must be ___________ is chemically altered
regenerated
Cofactors contain
2 enzymes
2 reactions
prosthetic groups contain
one enzyme (stays attached)
two reactions
True catalysts cannot undergo ______ ________ ________: cofactors must be ____________________
permanent chemical change
regenerated
In an enzymatic kinetic graph, the curve levels off when the reaction _______________
reaches equilibrium
Km =
[S] at Vmax/2
When an enzyme has a high Km it has a __________ affinity for the substrate
lower
When an enzyme has a low Km it has a __________ affinity for the substrate
high
Why is the M&M equation / analysis helpful
- Elucidate physiological role of enzymes
- Study inhibition action for therapeutics
Where is glucokinase found and at what [] does it work best at
liver, B cells of pancreas
[High]
Where is hexokinase found and at what [] does it work best at
most tissue including liver
[low]
What is the physiological relevance of gluc/hex
the higher Km of gluc. allows the liver to respond to increases in glucose to capture extra glucose when hex is saturated
Km of Hex and Km of Gluc
~1 mM and ~7mM
What are isozymes
distinct enzymes that catalyze the same biochemical reaction
Isozymes exist within ______, within an. individual at different stages of development, within the same __________ or even same ________
species. tissue, cell
Isozymes can have subtle or significant differences in __________
primary structure
How can you distinguish isozymes
kinetics/ regulatory properties
Creatine Kinase can be found in ______ and _________
myocardial infarction and muscle disorders
Lactate Dehydrogenase can be found in both
muscle disorders, liver disease
The pharmaceutical actions of drugs are due to their ability to ___________ enzymes specifically
inhibit