1 / 6

Determination of the Isoelectric Points of Casein

Due to its amphoteric nature, the solubility of casein greatly depends on the pH of the medium. Different pH values can help determine the isoelectric point of casein using an acetate buffer. Adding specific reagents like ethanol can precipitate casein at its isoelectric point. This experiment involved a series of tube setups to calculate the pH using the Henderson-Hasselbalch equation.

njoseph
Download Presentation

Determination of the Isoelectric Points of Casein

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Determination of the Isoelectric Points of Casein • Due to its amphoteric nature, the solubilty of casein depends greatly on the PH of the medium.

  2. Determination of the Isoelectric Points of Casein • Certain proteins e.g. gelatin are relatively soluble in water even at their I.E.P. BUT maximum precipitation can be obtained at the the isoelectric point by addition of some reagents such as, ethanol which dehydrates the molecule and allow neutralization of charge.

  3. * Principle • Using acetate buffer of different PH values the approximate position of the isoelectric point of casein can be obtained by determining the PH of minimum solubility. • The PH of any solution can be calculated from Handerson-hasselbalch equation. PH = Pka + log [Sodium acetate] [acetic acid]

  4. Tube # 1 2 3 4 5 6 7 0.05% casein solution in 0.1ml CH3COONa 1 1 1 1 1 1 1 (ml) Distilled Water (ml) 8.4 8 8.8 8.5 8 7 7.4 0.01M acetic acid (ml) 0.6 1 - - - - - 0.1M acetic acid (ml) - - 0.2 0.5 1 2 - 1M acetic acid (ml) - - - - - - 1.6

  5. * Results

  6. * Results PK acetic acid = 4.5 PH = PKa + log [CH3COONa] [CH3COOH] Samar A. Damiati

More Related