Protein molecular weight calculator kDa
How do you quickly convert protein size measured in kDa or microgram into picomole – and vice versa?
The rule of thumb for conversion of microgram amounts into picomole amounts at different protein molecular weights and peptide molecular weights is as follows:
1000/Mw of protein in kDa = pmol/µg
You can also use the table below for quick conversion of your protein amount, depending on its size:
| Protein size kDa | Microgram | Picomole | Microgram | Picomole |
| 1 | 1 | 1000 | 1 | 1000 |
| 10 | 10 | 1000 | 1 | 100 |
| 20 | 20 | 1000 | 1 | 50 |
| 50 | 50 | 1000 | 1 | 20 |
| 100 | 100 | 1000 | 1 | 10 |
| 150 | 150 | 1000 | 1 | 6.7 |
Learn more about the properties of your protein
The above table is beneficial when you are simply calculating the size of proteins in kDa.
However, in other situations, you may want to learn more about the properties of your protein. In those cases, the GPMAW lite tool will come in handy. It is free, highly accurate, and easy to use.
It can, e.g., be used to check out the theoretical protease digestion of your protein and save you time in the laboratory by choosing the best protease, as it can be pretty time-consuming to work in the blind and run several protein digestions side-by-side. Several proteases are often used in combination for analyses like peptide mapping to achieve full sequence coverage. Thus, often used proteases include trypsin, chymotrypsin, Glu-C, Lys-C, pepsin, thermolysin, and Asp-N.
It also helps you identify specific amino acids and locations of modifications, such as glycosylation sites. These tasks are essential to both aspiring and established protein analysts. Especially before intact mass analysis, it is necessary to determine the theoretical protein size in kDa and be aware of modifications that may affect the investigation.
Moreover, you can use GMPAW lite to run the conversion into protein size in kDa and obtain protein properties. Simply access the calculator by your internet browser (e.g., on your phone or laptop) as there is no need to download an app.
Try GPMAW lite – free bioinformatics tool
Helpful Links and Protein Molecular Weight Calculator
This section contains some helpful links for your further work with proteins. Feel free to share them with a colleague or friend who you think will also benefit from them. Should you have questions about the GPMAW lite tool or protein analysis in general, please reach out to Alphalyse for help.
Use this free tool if you would also like to calculate the basic properties of your protein: Free protein bioinformatics tool GPMAW lite
Similarly, use this link to learn how to compute the pI/Mw tool from a protein amino acid sequence or a database accession number: https://web.expasy.org/compute_pi/
On the Alphalyse website, you can find more information on how to perform molecular protein weight (MW) determination by mass spectrometry on the Alphalyse website. For example on these pages about Molecular Weight Determination and Intact Mass Analysis
Furthermore, you can learn more about how you can make simple bioinformatics calculations on specific protein sequences in this blog post.