5.   ‘‘Enzymes (catalysts in general) speed up a reaction without entering
      into the reaction.”
      Although a catalyst, or an enzyme, is the same after a reaction has occurred
      and appears to be unchanged, it plays a very active part in the reaction and
      undergoes changes that involves breaking and forming new bonds in the
      enzyme as well as in the substrate. Just as with other catalysts, the enzyme
      forms an enzyme-substrate complex, equivalent to the activated complex
      formed by most chemical catalysts.

6.   ‘‘Enzymes increase the amount of product formed by changing the
      equilibrium point of a reaction.”
      Enzymes do not change the equilibrium point of a chemical reaction. They
      only affect the rate at which the equilibrium point is approached.
 

1831   Berzelius assumed that certain substances contain a ‘‘catalytic force” that
           permitted them to accelerate a reaction.
1833   Jean Persoz and Anselme Payer prepared a malt extract that converted
           starch to dextrins. They called this substance diastase from the Greek word
           that means ‘‘breaking.” We now call this enzyme amylase.
1836   Theodor Schwann showed that a living cell (yeast) was required for
           fermentation.
1845   Mialhe discovered diastase in saliva and called it animal diastase.
           Bouchardat, Sandras and Valentin found the same substance in pancreatic
           juice and suggested that the pancreas be called the abdominal salivary
           gland.
1876   Kuhne suggested the name enzyme, from the Greek word meaning leaven.
           Such substances were previously called “ferments.”
1883   As more enzymes were discovered, Duclaux suggested that all enzymes be
           named to end in -ase, as in diastase.
1897   Eduard Buchner accidentally isolated zymase from yeast and showed it to be
           the active enzyme in yeast.
           Bertrand proposed the first enzyme-activation scheme: calcium and pectase
           to form the active enzyme, pectinase.
1913   Michaelis performed the first kinetic studies on enzymes.
1926   James Sumner crystallized urease from jack bean meal and showed that it
           was a protein.
1930   John Northrop crystallized pepsin and showed that it was also a protein. He
           suggested that all enzymes are protein.
 

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