Kininogenases

Kininogenases are a group of enzymes that play a crucial role in the kinin-kallikrein system, a complex cascade involved in various physiological processes. These enzymes are primarily responsible for cleaving kininogens, which are large precursor proteins, to release biologically active peptides called kinins. The most prominent kinin is bradykinin, known for its potent vasodilatory and inflammatory effects.

There are two main classes of kininogenases: plasma kininogenases and tissue kininogenases. Plasma kallikrein, found in the blood, is a major plasma kininogenase. It circulates as an inactive precursor, prekallikrein, and is activated by activated Factor XII. Tissue kallikreins, on the other hand, are found in various organs and tissues, including the salivary glands, pancreas, and kidneys. These tissue enzymes exhibit distinct substrate specificities and physiological roles.

The kinin-kallikrein system, initiated by kininogenases, is involved in regulating blood pressure, inflammation, pain perception, and smooth muscle contraction. Dysregulation of kininogenase activity has been implicated in a range of pathological conditions, including hypertension, inflammatory diseases, and thrombosis. Therapeutic strategies targeting kininogenases or their products are being investigated for the treatment of these conditions.