Can a protein complex be a machine? Discussing an article with friends we began discussing whether a protein complex that punches holes in cells (membrane attack complex) would be considered a machine.

Now, my friends are biochemistry students while I am a computer science student so this is far from my expertise. In my imagination this would be a mechanical action, hence the definition of a machine found on Wikipedia.
My friends counter argument is more of an emotional one, saying it feels wrong to call it a machine but also couldn't come up with a better word.

So:
Is it a machine? Is it something else? Or is a complex just a complex?
Does chemistry/biology have its very own definitions for things that do stuff in coordination without being "alive"?
According to the Oxford dictionary, a machine is:


  An apparatus using mechanical power and having several parts, each with a definite function and together performing a particular task.


Based on that definition, I think some proteins and enzymes could definitely be considered machines. A good example for that, in my opinion, would be ATP Synthase and all of the proteins that participate in the oxidative phosphorilation process.