As far as I know Iron is used in many enzymes as the metal complex. Beyond this are there any biological uses for iron? All uses appreciated, ty.
here the most prominent example i know of is its presence in haemoglobin, a protein that makes use of iron to bind oxygen and transport it around the body
Nope. Complexes are pretty much all iron does. The above poster's example of hemoglobin is an example of an iron complex.
Yes, but hemoglobin is a protein, not an enzyme, so his post is a valid example of another use of iron. Incidentally, have you ever noticed that if you smell your finger after picking at a scab with a little blood on it, that is smells strongly like iron?
But the iron is still acting through forming a complex - in this case, it is actually a heme porphyrin. The fact that the iron isn't performing a reaction is a mere technicallity - there are many iron-porphyrins that DO catalyze reactions.
Enzymes are proteins too. But hemoglobin is not an enzyme. Regardless, I think you've gotten the answer you were seeking, correct?