6 replies to this topic

[ujla80]

hi all

i have checked the original paper of lowry for protein analysis but i didn't get the idea why we add sodium-potassium tartarate in the lowry reagent and i also want to know that does follin reagent react with free aromatic amino acids.

ujla80

[mdfenko]

ujla80, on Jun 25 2009, 11:38 AM, said:

i have checked the original paper of lowry for protein analysis but i didn't get the idea why we add sodium-potassium tartarate in the lowry reagent

i'm not sure if it is the only reason but the tartrate helps keep the copper in solution.

[ujla80]

thanks.... can you please tell me how does sodium-potassium tartrate helps keep copper in solution? does it inhibit the copper precipitation?

[klinmed]

ujla80, on Jun 25 2009, 05:38 PM, said:

hi all

i have checked the original paper of lowry for protein analysis but i didn't get the idea why we add sodium-potassium tartarate in the lowry reagent and i also want to know that does follin reagent react with free aromatic amino acids.

ujla80

The method is based on the biuret reaction. Tartrate is added as a chelator (stabilizer) as it forms the soluble complex ion "alkaline copper tartrate".  The Lowry reaction mechanism is not well understood, but involves reduction of the Folin reagent and oxidation of aromatic residues (mainly tryptophan, also tyrosine).

Hope this helps.

[mdfenko]

here is some literature to help you understand the chemistry:

Attached Files

•  Protein_Assay_handbook.pdf   1.67MB   195 downloads

[mdfenko]

and these originals:

Attached Files

•  folin_reagent.pdf   1.37MB   189 downloads
•  lowry_protein_assay.pdf   681.45K   167 downloads

[ujla80]

thank you so much for giving me the literature...it is really helpfull... now it is clear to me that free tryptophan and tyrosine do react with folin-reagent to enhance the blue color in lowry.