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what amino acid substitution results in sickle cell?
substitution of valine for glutamate
true or false? the capillary beds in your feet have low CO2 partial pressure
What is the significance of KM
Km is equal to the substrate concentration at which the reaction velocity is half its maximal value
is the Km of different enzymes the same? explain your answer
no, because the Km is a compilation of enzyme rate constants--each of which are unique to their respective enzymes
Why does the enzyme velocity increase with increasing substrate concentration?
increasing the substrate concentration will increase the enzyme velocity IF the enzyme is not yet saturated (that is, if there isn't more substrate concentration than enzyme concentration). This is because, when an enzyme isn't saturated, adding more substrate means more substrate is converted into product by the more abundant enzyme
what is k?
k is the rate constant. the rate of the reaction is directly related to the concentration of the reactant(s) by this constant.
when one plots 1/V0 as a function of 1/[S], what plot does one get?
a Lineweaver-Burk plot
true or falsE? experimental evidence suggests that the Vmax value provides an approximation of substrate concentration in vivo?
false. experimental evidence suggests that the Km value provides an approximation of substrate concentration in vivo
the turnover number is the number of...
the turnover number is the number of substrate molecules that an enzyme can convert into product per unit time when the enzyme is fully saturated with substrate
what is the turnover number equal to?
the turnover number is equal to the rate constant k2, which is also called kcat
What is the significance of kcat/KM ?
is the rate constant for the interaction of S and E. It is ameasure of the catalytic efficiency because it takes into account both the rate of catalysis with a particular substrate (kcat) and the strength of the enzyme-substrate interaction (KM
). For instance, by using kcat/KM
values, we can compare an enzymes preference for different substrates.
Look at the following table to see the kcat/KM
values for several different substrates of chymotrypsin:
what are the two types of biochemical reactions that involve two substrates?describe them.
How could the following reaction pathway be coordinated in such a way to produce the appropriate amount of K?
Compound F could stimulate e10
but inhibit e1
to balance the amount of I with F. Likewise, compount I could inhibit e10
while stimulating e1
the effects of substrates on allosteric enzymes are referred to as ________ effects
the effects of regulatory molecules on allosteric enzymes are referred to as _______ effects