Quantification of Protein Bands in SDS-PAGE Gels:

A good method of protein quantification is to simply measure the density of protein bands in stained SDS-PAGE gels. This is simple and quite accurate and has some other advantages. For example it is possible to measure only the protein band you are interested in, ignoring contaminants which may be irrelevant to your work. Also it is easy to compare the densities of two protein bands, perhaps using one as a built in standard. Now we are in the digital era, it has become relatively easy to do this, using a digital camera and appropriate software. The method is also inexpensive, as good digital cameras cost a few hundred dollars and good software can be obtained from the internet for free.

We use a Nikon D200 camera with a 15-70mm zoom lens and the ImageJ software. The camera is not ideal for the purpose, as a dedicated macro lens would be a little easier to use. However the camera does well enough, and takes pictures of many other things at weekends. The camera is a single lens reflex which makes focusing easy. ImageJ instructions and download links can be accessed from here. The program was written in the National Institutes of Health. It is public domain and the source code can be modified by a user with the requisite computer skills for specific purposes. ImageJ was written in the Java programming language, and as a result works in the same way on Windows PCs, Macs and Unix/Linux/Ubuntu PCs. You probably have the Java Virtual Machine running on your computer already, and if not, you can download it from the ImageJ site.

Disclaimer: This program was constructed primarily to save time for busy researchers around the world. We hope you find it useful, and we are confident that it is accurate and reliable. However, we cannot be held responsible for any problems which may arise as a result of the use of this program.

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