Dear Nkwi Flores

you can try to see if the imageJ software can work for your purpose. I used it in the windows sistem but from the website it seems that it is also avaialble for the MAC

https://imagej.net/ij/download.html

in the following link

https://proteocool.blogspot.com/2021/09/tips-of-week-13-densitometric-protein.html

you can see and example of using of imageJ for SDS-page analisys.

good luck

Manuele

Manuele Martinelli, thank you for the response; it is very helpful. I have a follow-up question. I cannot find the documentation to interpret the pick measurements. I would like to calculate the molecular weight of unknown proteins.

Dear Nkwi Flores

Sincerelly i never use imageJ for this purpose but just to quantify the intensiry of the bands.

However you can try by selecting your protein and the marker 2 separate lanes with the sample procedure reported in my blog

https://proteocool.blogspot.com/2021/09/tips-of-week-13-densitometric-protein.html

once you have selected it you can plot the line profile and instead define the base line and determine the peak intensity you can try to go to:

Analize --> Tools --> Analize line graph

once the line graph is open, you can try to desing a line form the end of the gel to the center of each peak of the marker line, measure the lenght iof the line and correlate by excell the leght with the MW.

In this way you can try to buld a calibration line that correlate pixels and MW and determine its equation by linear regression fitting.

Then you can measure the lenght of the run for your protein in the 2nd line and calculate the MW using the previous equation.

For curiosity, just tried to do this analisys on a full lenght mab igg1 mouse runned in a 3-8% SDS-page in non reducing condition and the MW prediction was about 180KDa which is not highly accurate but not so bad considering the general accuracy of SDS-page.

I hope that you can undertand those my brief instruction.

Actually i'm quite busy and i'm not able to provide you a more clear and extende guidelines but i will try to do it and post on my blog (ProteoCool) in the next weeks.

best

Manuele

Manuele Martinelli, thank you for the notes. They help explore different ways to analyze it.