D. bind their substrates at active sites. E. all statements are true. Enzymes are composed primarily of proteins, which are polymers of amino acids. Enzymes can bind prosthetic groups that participate in enzyme reactions. Prosthetic are not part of the enzyme polypeitide chain.
Prosthetic groups can be metal ions or various types of organic compounds.
Enzymes fold into defined, 3D conformations. The three dimensional structure of many enzymes has been determined. As an example, the defined structure of the enzyme lysozyme with a carbohydrate substrate bound to the active site is shown in the left panel of the figure. Enzymes bind their substrates at active sites. The active site is the location on the surface of the enzyme where the catalyzed reaction takes place.