What is an active site and what is its relationship to an enzyme? an active site in an enzyme is the area that breaks the bond in its substrate. E.g. a maltose molecule's glycocide bond is broken by the active site in a maltase enzyme.
The caffeine in a cup of coffee might help your small blood vessels work better. Credit: Â© jogyx / Fotolia. The caffeine in a cup of coffee might help your small blood vessels work better, according to research presented at the American Heart Association's Scientific Sessions 2013.
Others, whose body has become used to the drug, may be able to drink more than three or four cups of coffee without experiencing any outward signs. Inwardly, blood pressure, cholesterol, heart and metabolic rates, respiration and blood glucose concentration are all affected by caffeine.