Are all proteins enzymes?

If all enzymes are proteins but all proteins are not enzymes then what makes enzymes different from proteins?

• Answer:

  Enzymes are proteins that act as a catalyst, lowering the activation energy of a reaction, therefore dramatically increasing the rate of the reaction. An example of this is the enzyme betagalactosidase which binds the lactose substrate, lowering the activation energy, therefore increasing the rate at which this reaction forms its monosaccharidal units, glucose and maltose. On the other hand proteins can act as transportational and structural elements within the cell, rather than catalysts. It must also be noted that not all enzymes are proteins. I am not sure of the direct terminology (wikipedia will help) but ribosomes are enzymes that are not proteins.