Are you running any controls lanes with known protein? It could be a problem with the gel, it could be a problem with your protein preparation and the proteins are degraded (or there is just not enough protein in the samples you are loading), it could be a problem with your staining/destaining procedure.

Running some standard controls would be helpful to diagnose the issue.

Are you boiling your samples before loading to the gel? Are you adding Laemmli sample buffer at the proper concentration to the samples?

If you´re doing all the previous, then It looks like you have no protein in your solution. At 1.7 mg/ml you should see protein (limit of detection is about 500 ng for Comassie). Are there anything that may interfere in the Biuret assay? Try to measure protein concentration using another method: Bradford, BCA, or Absorbance at 280 nm.

Michael J. Benedik Yes sir.. iam running wide range markers and observed the bands.. iam attaching one photo of SDS gel.. kindly see it once..

Carlos Lopez-Robles Yes sir.. i will try with barford assay.. Thank you..

There are a few possible reasons for not seeing any bands on SDS-PAGE gel: 1. Your sample may not be properly denatured. Make sure to denature your sample for an appropriate amount of time and temperature before loading it onto the gel. 2. The concentration of your sample may be too low. Make sure to use enough sample in order to get visible bands. 3. The gel may not be of sufficient quality or the running conditions may not be optimal. Make sure to use good quality gels and running conditions to get the best results. 4. Your sample may contain inhibitors. Make sure to check for any inhibitors in your sample that may be preventing the proteins from migrating properly.

Bandla Ramesh After extraction, when i performed kjeldahl and DUMAS its showing protein around 60%. But when iam performing colorimetric methods before SDS PAGE color is not changing.. Is there any reason behind this? If there, what could be the solution for this?