Ferritin is treated with SDS or SDS and b-mercaptoethanol and subjected to polyacrylamide gel electrophoresis. Only when very large amounts of bisacrylamide are added do you see two separate bands on the gel at relative migrations of 4.0245 and 3.9375 and the results are the same with and without b-mercaptoethanol. You decide to call these the light and heavy chains of ferritin. What are the actual sizes of the light and heavy chains of ferritin based on the SDS-PAGE data? What types of interactions hold these proteins together in the structure of ferritin?

Biochemistry
9th Edition
ISBN:9781319114671
Author:Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.
Publisher:Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.
Chapter1: Biochemistry: An Evolving Science
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Ferritin is treated with SDS or SDS and b-mercaptoethanol and subjected to polyacrylamide gel electrophoresis.  Only when very large amounts of bisacrylamide are added do you see two separate bands on the gel at relative migrations of 4.0245 and 3.9375 and the results are the same with and without b-mercaptoethanol.  You decide to call these the light and heavy chains of ferritin. 

 

What are the actual sizes of the light and heavy chains of ferritin based on the SDS-PAGE data? What types of interactions hold these proteins together in the structure of ferritin? 

**Standard Curve SDS-PAGE**

This graph represents a standard curve used in SDS-PAGE (Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoresis) to determine protein molecular weights. The y-axis displays the logarithm of the molecular weight in kilodaltons (log[molecular weight] [kDa]), while the x-axis shows relative migration, which refers to how far proteins have moved through the gel.

### Detailed Explanation:

- **Data Points**: Individual blue dots represent proteins with known molecular weights and their corresponding relative migration distances observed during the electrophoresis.

- **Trendline**: A dotted line fits the data, following a linear trend expressed by the equation:
  \[
  y = -0.4996x + 3.2894
  \]
  Here, `y` is the log(molecular weight) and `x` is the relative migration. The slope is -0.4996, and the y-intercept is 3.2894.

- **Coefficient of Determination (R²)**: The R² value is 0.9984, indicating a very high correlation between relative migration and log(molecular weight), suggesting a reliable model for predicting unknown protein sizes.

This standard curve is an essential tool in molecular biology for estimating the sizes of proteins based on their migration through an SDS-PAGE gel.
Transcribed Image Text:**Standard Curve SDS-PAGE** This graph represents a standard curve used in SDS-PAGE (Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoresis) to determine protein molecular weights. The y-axis displays the logarithm of the molecular weight in kilodaltons (log[molecular weight] [kDa]), while the x-axis shows relative migration, which refers to how far proteins have moved through the gel. ### Detailed Explanation: - **Data Points**: Individual blue dots represent proteins with known molecular weights and their corresponding relative migration distances observed during the electrophoresis. - **Trendline**: A dotted line fits the data, following a linear trend expressed by the equation: \[ y = -0.4996x + 3.2894 \] Here, `y` is the log(molecular weight) and `x` is the relative migration. The slope is -0.4996, and the y-intercept is 3.2894. - **Coefficient of Determination (R²)**: The R² value is 0.9984, indicating a very high correlation between relative migration and log(molecular weight), suggesting a reliable model for predicting unknown protein sizes. This standard curve is an essential tool in molecular biology for estimating the sizes of proteins based on their migration through an SDS-PAGE gel.
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