Active centre

noun
(biochem) the region in an enzyme molecule in which the reactive groups that partic-p-te in its action are juxtaposed also called active site
historical examples

wallingford, six miles above streatley, is a very ancient town, and has been an active centre for the making of english history.
three men in a boat jerome k. jerome

new orleans is not so large; its active centre is very small.
bonaventure george washington cable

it was an active centre of mining, and became a stannary or coinage town.
the cornwall coast arthur l. salmon

this active centre of the thoughts of a century, was sustained during the whole time by the storm of perpetual political conflict.
history of the girondists, volume i alphonse de lamartine

they were zealous buddhists, and under their rule magadha became once more an active centre of buddhist influence.
encyclopaedia britannica, 11th edition, volume 3, slice 5 various

an active centre of origin appears to exist in south-eastern europe, from which the species radiate out in all directions.
the history of the european fauna r. f. scharff

there is an active centre of distribution in south-eastern europe itself, from which species radiate out in all directions.
the history of the european fauna r. f. scharff

at thebes, then, was the active centre of the influence that drew my friend away from modern things.
incredible adventures algernon blackwood