Protein Assay

BMS1023 – Laboratory Practical: Biuret Protein Assay & Standard Curve

Practical 3 Report

1. Standard curve […/10]:

BSA Standard Curve: |

Tube number | 1 & 2 | 3 & 4 | 5 & 6 | 7 & 8 | 9 & 10 | 11 & 12 | 13 & 14 |

Final BSA concentration (mg/ml) | 0 | 0.5 | 1 | 2 | 3 | 4 | 5 |

Volume of BSA (5 mg/ml) required (ml) | 0 | 0.1 | 0.2 | 0.4 | 0.6 | 0.8 | 1.0 |

Volume of 0.5M NaOH (ml) | 1.0 | 0.9 | 0.8 | 0.6 | 0.4 | 0.2 | 0 |

Absorbance | 0.0000.000 | 0.0410.043 | 0.0840.085 | 0.1710.171 | 0.2540.234 | 0.3650.359 | 0.4860.486 |

2. “Unknown” samples (in triplicate) […/10]:

Tube number/Duplicate | 15-17 | 18-20 | 21-23 | 24-26 | 27-29 |

Volume of samples (ml) | 1 ml of A | 1 ml of B | 1 ml of C | 1 ml of D | 1 ml of E |

Absorbance values (triplicates) | 0.4070.4120.374 | 0.042 0.0430.048 | 0.2370.2470.247 | 0.0210.0240.027 | 0.2870.2910.291 |

Average | 0.398 | 0.044 | 0.244 | 0.024 | 0.290 |

3. Plot the standard curve on graph paper and fit the data points to a straight line. Include a digital copy of your graph in this report […/20]

4. Calculate the protein concentration of your “unknown” samples […/20]:

Unknown | Absorbance values | Average | Dilution factor | [Protein] (mg/mL] |

A | 0.407 | 0.412 | 0.374 | 0.398 | 1 | 4.75 |

B | 0.042 | 0.043 | 0.048 | 0.044 | 10 | 4.50 |

C | 0.237 | 0.247 | 0.247 | 0.244 | 1 | 2.90 |

D | 0.021 | 0.024 | 0.027 | 0.024 | 10 | 3.50 |

E | 0.287 | 0.291 | 0.291 | 0.290 | 1 | 3.45 |

Note:

* Samples A, C and E are undiluted.

* Samples B and D are 1/10 dilutions of samples A and C, respectively. The samples were diluted with 0.5 M NaOH.

5. How did you determine the concentration of your “unknown” samples? Provide a brief description […/20]

To determine the protein concentration of the “unknown” samples I firstly draw a graph with the absorbance values on the y-axis and the final BSA...