====== Protein determination ======

===== Introduction =====

To determine the content of protein in biological matter one can preferably use the either the Lowry or the Bradford test (BioRad protein assay).

==== Reagents ====

  * Sodium deoxycholate, Na-DOC, 2% solution (2g/100mL)
  * Sodium hydroxide, 4M
  * Reagent D:
    * Copper sulphate, 2% solution (2.5g/250mL)
    * Sodium potassium tartrate, 4% solution (5g/250mL)
    * Sodium carbonate, 2% solution (20g/L)
  * Folin-Ciocalteaus reagent, ready-made
  * Standard:
    * 0.02% albumin solution, (20mg/100mL)
    * Blank: 0.5mL water

[[chemicals|Full list of chemicals]]

==== Procedure ====

  - Take x mL protein solution and dilute to 0.5 mL. Add 0.15mL each of the Na -DOC and the NaOH solution.
  - Take 0.10, 0.15 and 0.20mL of the standard albumin solution. Dilute to 0.5mL and add 0.15mL each of the NaDOC and the NaOH solution.
  - Leave the samples, the standards and blank for 10 minutes.
  - Make reagent D by mixing 0.5mL of CuSO<sub>4</sub> solution, 0.5mL of Tartrate solution and 49mL of the Na<sub>2</sub>CO<sub>3</sub> solution. Add 3.0mL of reagent D and leave for 10 minutes (maximum 3 hours)
  - Folin-Ciocalteaus reagent (0.3 mL) is added immediately shaken and allowed to stand for exactly 30 min.
  - Read at 750nm against blank.