Chapter 11, Problem 6RTC

Summary Introduction

(a)

To write:

Experiment to prove that GLUT-1 is glucose specific uniporter.

Introduction:

GLUT1 is uniporter specific for glucose. It facilitates the transport of glucose across the plasma membrane. It is found in the erythrocytes cell membrane.

Explanation of Solution

GLUT1 is a glucose uniporter which facilitates the transport of glucose across the plasma membrane. It is encoded by SLC2A1 gene.

The conformation of GLUT1 makes it distinct. It has binding sites at transmembrane segments 9, 10 and 11 which only binds to glucose. To prove that GLUT1 is glucose specific uniporter we need to perform certain experiments. For this experiment, we use sodium ions as glucose cotransporter. When the experiment is done, we see that galactose and mannose do not bind to the GLUT due to the different structure than glucose. Also, we can perform DLS to detect glucose specific binding sites.

Conclusion

GLUT1 enzyme has specific conformation for the glucose only. It does not transport any other carbohydrate.

(b)

To write:

Reason for ribose not binding to GLUT1.

Introduction:

GLUT1 has specific conformation for glucose. It helps the glucose to pass the plasma membrane of the cell. So that glucose can provide energy to the cell.

Ribose is a 5-carbon sugar and glucose is a 6 carbon sugar. But glucose can bind to the GLUT1 and ribose can not. The reason is that enzymes are not size dependent. They are based on the conformation of the substrate. So, it does not matter if the size of the ribose is smaller than the glucose. GLUT1 accepts conformation of glucose only not ribose.

Ribose does not bind to the GLUT1 because the binding site of GLUT1 enzyme only accepts the conformation of glucose.

Summary Introduction

(c)

To write:

Effect on glucose transport activity of GLUT1 if the blood glucose level falls.

Introduction:

Glucose is the main source of energy for our body. If the glucose level falls, then our cells will get short of glucose and energy will not be formed in our body. This condition is termed as hyperglycemia. GLUT1 is the glucose transporter enzyme. It transports the glucose from blood plasma into the cells.

(b)

To write:

Reason for ribose not binding to GLUT1.

Introduction:

GLUT1 has specific conformation for glucose. It helps the glucose to pass the plasma membrane of the cell. So that glucose can provide energy to the cell.

Ribose is a 5-carbon sugar and glucose is a 6 carbon sugar. But glucose can bind to the GLUT1 and ribose can not. The reason is that enzymes are not size dependent. They are based on the conformation of the substrate. So, it does not matter if the size of the ribose is smaller than the glucose. GLUT1 accepts conformation of glucose only not ribose.

Ribose does not bind to the GLUT1 because the binding site of GLUT1 enzyme only accepts the conformation of glucose.

Expert Solution

Explanation of Solution

Ribose is a 5-carbon sugar and glucose is a 6 carbon sugar. But glucose can bind to the GLUT1 and ribose can not. The reason is that enzymes are not size dependent. They are based on the conformation of the substrate. So, it does not matter if the size of the ribose is smaller than the glucose. GLUT1 accepts conformation of glucose only not ribose.

Conclusion

Ribose does not bind to the GLUT1 because the binding site of GLUT1 enzyme only accepts the conformation of glucose.

Summary Introduction

(c)

To write:

Effect on glucose transport activity of GLUT1 if the blood glucose level falls.

Introduction:

Glucose is the main source of energy for our body. If the glucose level falls, then our cells will get short of glucose and energy will not be formed in our body. This condition is termed as hyperglycemia. GLUT1 is the glucose transporter enzyme. It transports the glucose from blood plasma into the cells.

Expert Solution

Explanation of Solution

  $V=\frac{V\max \left[S\right]}{Km+\left[S\right]}$

The above equation is Michalis Menten equation. This equation is for the enzymes. The parameters meaning are as follows:

Vmax = maximum initial rate of a reaction

Km = concentration of the substrate when Vmax is half

[S] = concentration of the substrate.

For any enzyme the values of Vmax and Km are different. Value of Km = 26.2mM and value of Vmax = 3.5nmol/min/cell. From the question, we get the value of [S] as 5mM and 2.75mM. using these values, we can determine the change in GLUT1 activity for glucose.

Calculating the value of V (rate of reaction) for [S] = 5mM

  $\begin{array}{l}V=\frac{V\max [S]}{Km+[S]}\\ V=\frac{3.5\times 5}{26.2+5}\\ V=0.56nmol/\min /cell\end{array}$

Calculating the value of V (rate of reaction) for [S] = 2.75 mM

  $\begin{array}{l}V=\frac{V\max [S]}{Km+[S]}\\ V=\frac{3.5\times 2.75}{26.2+2.75}\\ V=0.331nmol/\min /cell\end{array}$

So, as the concentration decreases the rate of the reaction decreases. So as the rate of reaction decreases the uptake of glucose is decreased by the GLUT1 enzyme. This results in less transport of glucose to the cell and hence less formation of energy by the cell.

Conclusion

As the concentration of the substrate decreases the rate of the enzymatic reaction decreases. When the glucose concentration is 5mM the rate of the reaction is 0.56nmol/min/cell. When the glucose concentration is 2.75mM then the rate of the reaction is 0.331nmol/min/cell. So, as the glucose level falls in the blood then the rate of the enzymatic reaction goes down. This results in less transfer of glucose molecules across the plasma membrane.

Summary Introduction

(c)

To write:

Effect on glucose transport activity of GLUT1 if the blood glucose level falls.

Introduction:

Glucose is the main source of energy for our body. If the glucose level falls, then our cells will get short of glucose and energy will not be formed in our body. This condition is termed as hyperglycemia. GLUT1 is the glucose transporter enzyme. It transports the glucose from blood plasma into the cells.

Expert Solution

Explanation of Solution

  $V=\frac{V\max \left[S\right]}{Km+\left[S\right]}$

The above equation is Michalis Menten equation. This equation is for the enzymes. The parameters meaning are as follows:

Vmax = maximum initial rate of a reaction

Km = concentration of the substrate when Vmax is half

[S] = concentration of the substrate.

For any enzyme the values of Vmax and Km are different. Value of Km = 26.2mM and value of Vmax = 3.5nmol/min/cell. From the question, we get the value of [S] as 5mM and 2.75mM. using these values, we can determine the change in GLUT1 activity for glucose.

Calculating the value of V (rate of reaction) for [S] = 5mM

  $\begin{array}{l}V=\frac{V\max [S]}{Km+[S]}\\ V=\frac{3.5\times 5}{26.2+5}\\ V=0.56nmol/\min /cell\end{array}$

Calculating the value of V (rate of reaction) for [S] = 2.75 mM

  $\begin{array}{l}V=\frac{V\max [S]}{Km+[S]}\\ V=\frac{3.5\times 2.75}{26.2+2.75}\\ V=0.331nmol/\min /cell\end{array}$

So, as the concentration decreases the rate of the reaction decreases. So as the rate of reaction decreases the uptake of glucose is decreased by the GLUT1 enzyme. This results in less transport of glucose to the cell and hence less formation of energy by the cell.

Conclusion

As the concentration of the substrate decreases the rate of the enzymatic reaction decreases. When the glucose concentration is 5mM the rate of the reaction is 0.56nmol/min/cell. When the glucose concentration is 2.75mM then the rate of the reaction is 0.331nmol/min/cell. So, as the glucose level falls in the blood then the rate of the enzymatic reaction goes down. This results in less transfer of glucose molecules across the plasma membrane.

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Chapter 11, Problem 5RTC

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Chapter 11, Problem 7RTC

Explanation of Solution

Ribose is a 5-carbon sugar and glucose is a 6 carbon sugar. But glucose can bind to the GLUT1 and ribose can not. The reason is that enzymes are not size dependent. They are based on the conformation of the substrate. So, it does not matter if the size of the ribose is smaller than the glucose. GLUT1 accepts conformation of glucose only not ribose.

Conclusion

Ribose does not bind to the GLUT1 because the binding site of GLUT1 enzyme only accepts the conformation of glucose.

Summary Introduction

(c)

To write:

Effect on glucose transport activity of GLUT1 if the blood glucose level falls.

Introduction:

Glucose is the main source of energy for our body. If the glucose level falls, then our cells will get short of glucose and energy will not be formed in our body. This condition is termed as hyperglycemia. GLUT1 is the glucose transporter enzyme. It transports the glucose from blood plasma into the cells.

Explanation of Solution

  $V=\frac{V\max \left[S\right]}{Km+\left[S\right]}$

The above equation is Michalis Menten equation. This equation is for the enzymes. The parameters meaning are as follows:

Vmax = maximum initial rate of a reaction

Km = concentration of the substrate when Vmax is half

[S] = concentration of the substrate.

For any enzyme the values of Vmax and Km are different. Value of Km = 26.2mM and value of Vmax = 3.5nmol/min/cell. From the question, we get the value of [S] as 5mM and 2.75mM. using these values, we can determine the change in GLUT1 activity for glucose.

Calculating the value of V (rate of reaction) for [S] = 5mM

  $\begin{array}{l}V=\frac{V\max [S]}{Km+[S]}\\ V=\frac{3.5\times 5}{26.2+5}\\ V=0.56nmol/\min /cell\end{array}$

Calculating the value of V (rate of reaction) for [S] = 2.75 mM

  $\begin{array}{l}V=\frac{V\max [S]}{Km+[S]}\\ V=\frac{3.5\times 2.75}{26.2+2.75}\\ V=0.331nmol/\min /cell\end{array}$

So, as the concentration decreases the rate of the reaction decreases. So as the rate of reaction decreases the uptake of glucose is decreased by the GLUT1 enzyme. This results in less transport of glucose to the cell and hence less formation of energy by the cell.

Conclusion

As the concentration of the substrate decreases the rate of the enzymatic reaction decreases. When the glucose concentration is 5mM the rate of the reaction is 0.56nmol/min/cell. When the glucose concentration is 2.75mM then the rate of the reaction is 0.331nmol/min/cell. So, as the glucose level falls in the blood then the rate of the enzymatic reaction goes down. This results in less transfer of glucose molecules across the plasma membrane.

Summary Introduction

(c)

To write:

Effect on glucose transport activity of GLUT1 if the blood glucose level falls.

Introduction:

Glucose is the main source of energy for our body. If the glucose level falls, then our cells will get short of glucose and energy will not be formed in our body. This condition is termed as hyperglycemia. GLUT1 is the glucose transporter enzyme. It transports the glucose from blood plasma into the cells.

Explanation of Solution

  $V=\frac{V\max \left[S\right]}{Km+\left[S\right]}$

The above equation is Michalis Menten equation. This equation is for the enzymes. The parameters meaning are as follows:

Vmax = maximum initial rate of a reaction

Km = concentration of the substrate when Vmax is half

[S] = concentration of the substrate.

For any enzyme the values of Vmax and Km are different. Value of Km = 26.2mM and value of Vmax = 3.5nmol/min/cell. From the question, we get the value of [S] as 5mM and 2.75mM. using these values, we can determine the change in GLUT1 activity for glucose.

Calculating the value of V (rate of reaction) for [S] = 5mM

  $\begin{array}{l}V=\frac{V\max [S]}{Km+[S]}\\ V=\frac{3.5\times 5}{26.2+5}\\ V=0.56nmol/\min /cell\end{array}$

Calculating the value of V (rate of reaction) for [S] = 2.75 mM

  $\begin{array}{l}V=\frac{V\max [S]}{Km+[S]}\\ V=\frac{3.5\times 2.75}{26.2+2.75}\\ V=0.331nmol/\min /cell\end{array}$

So, as the concentration decreases the rate of the reaction decreases. So as the rate of reaction decreases the uptake of glucose is decreased by the GLUT1 enzyme. This results in less transport of glucose to the cell and hence less formation of energy by the cell.

Conclusion

As the concentration of the substrate decreases the rate of the enzymatic reaction decreases. When the glucose concentration is 5mM the rate of the reaction is 0.56nmol/min/cell. When the glucose concentration is 2.75mM then the rate of the reaction is 0.331nmol/min/cell. So, as the glucose level falls in the blood then the rate of the enzymatic reaction goes down. This results in less transfer of glucose molecules across the plasma membrane.