How to find KO number for each protein represented by STRING ID?

Question

[larcwind]

Hi, community! :)

I am in need to find a functional annotation (KO number) of each protein (represented by STRING ID) in PPI networks. Specifically, I have five PPI networks extracted from STRING database and I would like to annotate each protein in the networks with KO numbers.
Previously, I did it as follows:

1. Download all annotations (ko00001.keg) from KEGG ORTHOLOGY database.
2. Convert all string IDs to gene names using the ID table provided by STRING database.
3. Find an annotation in ko00001.keg of each gene using python script.

Is there a more elegant or precise way to do this?

I appreciate your reading in advance. :)