Differentiate Holoenzyme and Apoenzyme? Apoenzyme Holoenzyme  An enzyme with its coenzyme, or prosthetic group, removed is designated as apoenzyme.  An activated enzyme consisting of polypeptide chain and a cofactor is known as holoenzyme.  It is inactive enzyme, Adding the correct concentration of coenzyme to the apoenzyme will restore enzyme activity.  It is an activated enzyme.  It consists of only protein.  It consists of both protein and non protein parts. Location of enzymes. Freely dispersed. Many enzymes are simply dissolved in the cytoplasm (e.g. Enzymes of glycolysis) Attached. Other enzymes are tightly bound to certain sub cellular organelles. They are produced by living cells for use in or near the site of their production. Chloroplasts. The enzymes important in photosynthesis are found in the chloroplasts. Mitochondria. Enzymes involved in cellular respiration are found in the mitochondria. Ribosomes. Some of the enzymes involved in the synthesis of proteins are integral part of ribosomes. Why some enzymes are secreted in inactive form? Some enzymes are potentially damaging if they are manufactured in their active from. For example, Pepsin is a powerful protein – digesting enzyme and is quite capable of destroying cell’s internal structure and thus is produced in inactive pepsinogen form by the cell. It is converted in its active from only in the digestive tract where it is required to be active. Characteristics of enzymes. • All enzymes are globular proteins. • They increase the rate of reaction without themselves being used up. • Their presence does not affect the nature of properties of end products. • Small amounts of an enzyme can accelerate chemical reaction. • They are very specific in their action; a single enzyme catalyzes only a single chemical reaction or a group of related reactions. • They are sensitive to even a minor change in pH, temperature and substrate concentration. • Some enzymes require a co-factor for their proper functioning. • They lower the activation energy of the reactions.