Hi

maybe this helps.

https://www.ptglab.com/support/western-blot-protocol/western-blot-troubleshooting-why-does-the-observed-protein-molecular-weight-mw-differ-from-the-calculated-one/

Best regards

Hello Kul Raj Rai

The major obstacle in recombinant protein production in E.coli is the formation of protein aggregates. In bacteria as there are no compartmentalization, proteins are simultaneously synthesized on multiple locations in the bacterial cytoplasm and various transitional folding states of the target protein are formed. The recombinant protein is incorporated into proto aggregates by cross molecular stereospecific interactions.

Sometimes these protein complexes are not fully disrupted, and proteins exist in the form of homo- or hetero- complexes even in the presence of reducing agents such as β-mercaptoethanol or SDS while performing Western Blot. These protein aggregates display a higher molecular weight, and so the observed molecular weight of the protein expressed in the prokaryotic system is higher than what you would expect theoretically.

I hope this helps.

Best Wishes.

Well different post translational modification for example remember that Gel electrophoresis just give apparent molecular weight. Migration of proteins are not always running consistent according to their predicted size