Question 31

[rbseeyore2025]

I guessed sigmoidal, the answer was hyperbola...

I googled what each graph looked like. It seems the hyperbola is a slope which comes up then down again. The sigmoidal peaks, and stays horizontal (which is what is being explained in the explanation). Also, taking into account michealis-menton plot (sp) for determining the shape of activity.

[jppepin6253]

A hyperbola looks similar to an exponential curve. There are four types of hyperbolas; they have assymatopes when approaching y=0 and x=0. In this problem, it helps if you make a graph. Initially, the enzyme is in a low concentration of substrate and as the concentration of substrate increases, the enzyme binding increases (looking like a linear curve). But once the concentration of the substrate is very high and there are no more spots on the enzymes to bind with the substrate (i.e. the enzyme is "saturated"...see saturated kinetics) and the curve starts to level out and become constant no matter how high the substrate concentration becomes. This is because there are no more spots for the substrate to bind with the enzyme.

[stoneprod7112]

I appreciate the explanation butstill don't understand why sigmoidal would not work since it does increase until it levels off which does seem to go along with the explanation. Is there more to the expodential increase pattern of a hyperbola curve?

[calena7178147]

The question states that the binding is not cooperative. Consider the classic model of cooperative/non-cooperative binding (Hemoglobin and Myoglobin)—they are proteins (not enzymes) that bind oxygen (substrate in enzyme models). Even though they are not enzymes, the principle is the same. Binding of oxygen to hemoglobin (blue curve) is cooperative. A sigmoidal curve is a characteristic of cooperative binding. After the first oxygen (like a substrate) molecule binds the second and third with much greater affinity. On the other hand, myoglobin (red curve) binds oxygen in a non-cooperative manner. Hyperbolic curves are characteristic of non-cooperative molecules. Once all of its sites are bound by oxygen(saturation point), then no more can bind. Remember the two bolded facts and you will not go wrong

[pinoalejan6739]

The sigmodial curve is the red one curve not the blue one. I don't know if am the one confused but it seems to me that if that the hyperbola curve is in blue which corresponds to cooperative binding.