Hence, early studies focused on proteins that could be purified in large quantities, e.g., those of blood, egg white, various toxins, and digestive/metabolic enzymes obtained from slaughterhouses.
Por iso, os primeiros estudos centráronse en proteínas que podían ser purificadas en grandes cantidades, como as do sangue, clara de ovo, varias toxinas e encimas dixestivos ou metabólicos obtidos en matadeiros.