What is the difference between a simple protein and a conjugated protein?

Simple proteins are made up of amino acid subunits joined together by peptide bonds. When hydrolyzed by enzymes, simple proteins yield only the amino acids from which they are comprised of. Examples of simple proteins include albumins, globulins, glutelins and albuminoids.

Conjugated proteins are complex proteins composed of simple proteins and a non-protein substance referred to as a prosthetic group or cofactor. Most prosthetic groups or cofactors are small organic molecules formed from vitamins. When hydrolyzed by enzymes, conjugated proteins yield the amino acids from which they are comprised of and some other chemical component. Examples of conjugated proteins include nucleoproteins, glycoproteins, phosphoproteins and hemoglobins.