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.
However, some people may be more vulnerable to the adverse effects of caffeine in coffee: Caffeine consumption comparable to the amount in 2-3 cups of coffee may raise blood pressure, especially in people with borderline or high blood pressure.