 BioCyc

Very good metabolism database.

Some things that they have of interest which may not be on NCBI:

Hits a free login wall after a few IP hits. And just a very normal casually browsing number of hits. What is this bullshit?

Their YouTube: www.youtube.com/channel/UCR9QDQ_9_N4isZV_YRQg9tA has some good tutorials.