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.
Unfiltered coffee raises serum cholesterol concentrations, but that effect is not due to caffeine but to a lipid that is absent from filtered coffee. The caffeine in coffee does cause an increase of 2.4 mm Hg in systolic blood pressure when 5 cups are consumed daily (9) (10).