March 10, 2012

Protein Analysis


Protocol for Total Protein Determination -Lowry et al., 1951   Last updated 4/9/2012 Sitti

 


REAGENT C
            2% Na2CO3 in 0.1N NaOH  - 50 ml
            0.5% CuSO4.5H20 in 1% Na Tartrate  - 1 ml
           
            REAGENT E
Diluted 1N Folin-Ciocalteu phenol reagent

PROTOCOL
1.      Filter 10 ml aliquot/culture onto pre-combusted GF/F filter (fold and wrap in aluminium foil -  store at -80 oC /LNG if not analyze) *make 3 replicates for each PBR tube.
2.      Homogenize filter in glass-teflon homogenizer in 3 mL 1N NaOH. Rinse 2-3 times homogenizer with 1N NaOH and collect as maximum extract as possible in a falcon tube, bring up the volume to 10 ml and cap tightly. 
3.      Keep the extract at room temperature for 22-24 hours for complete extraction.
4.      Vortex for thorough mix and centrifuge the extract for 5 mins at 5000 rpm. 
5.      Take 0.5  mL of extract and mix with 5 mL of freshly prepared reagent C.
6.      Allow to stand for 10 min. (in dark)
7.      Add 0.5 mL freshly prepared reagent E, mixed well.
8.      Allow to stand for 30 minutes to develop maximum colour.  (in dark)
9.      Read absorbance at 750 nm against a reagent blank.  
10.  Use Bovine serum albumin prepared in  1N NaOH  as standard for total protein contents determination.  To get the standard curves or calibration curves, prepare standard solution at concentration 0 - 150 µg/µl

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