How can we classify proteins depending on their composition?

Holoproteins (apoproteins) are proteins only made up of aa (whose hydrolysis results only in aa), that can be soluble or insoluble, heteroproteins, where aa polymers are conjugated to other non protein molecules (lipoproteins, nucleoproteins or ribonucleoproteins, glycoproteins, hemoproteins (heme group (metal inside) Hb that transports gases and cytochromes that catalyze oxidation-reduction rxns. the metal ion present in the heme center is iron, and other ions such as copper occur in other hemoproteins)