The molecular weight of glucose oxidase varies slightly depending on the source and specific form of the enzyme. However, a common value used is approximately 155,000 Da (Daltons).

Here's why it can vary:

* Different isoforms: Glucose oxidase exists in different isoforms (slightly different forms) with varying amino acid sequences.

* Glycosylation: The enzyme can be glycosylated (have sugar molecules attached), adding to its molecular weight. The extent of glycosylation can vary.

Therefore, while 155,000 Da is a widely used estimate, you might find slightly different values depending on the context and specific source of the enzyme.