Angiotensin-converting enzyme

Angiotensin-converting enzyme, or "ACE" indirectly increases blood pressure by causing blood vessels to constrict. It does that by converting is_associated_with::angiotensin I to is_associated_with::angiotensin II, which constricts the vessels. For this reason, drugs known as is_associated_with::ACE inhibitors are used to lower blood pressure.

ACE is also known by the following names: dipeptidyl carboxypeptidase I, peptidase P, dipeptide hydrolase, peptidyl dipeptidase, angiotensin converting enzyme, kininase II, angiotensin I-converting enzyme, carboxycathepsin, dipeptidyl carboxypeptidase, "hypertensin converting enzyme" peptidyl dipeptidase I, peptidyl-dipeptide hydrolase, peptidyldipeptide hydrolase, endothelial cell peptidyl dipeptidase, peptidyl dipeptidase-4, PDH, peptidyl dipeptide hydrolase, and DCP.

ACE, angiotensin I and angiotensin II are part of the is_associated_with::renin-angiotensin system (RAS), which controls blood pressure by regulating the volume of fluids in the body. ACE is secreted in the lungs and kidneys by cells in the endothelium (inner layer) of blood vessels.

Functions
It has two primary functions:
 * ACE catalyses the conversion of angiotensin I to angiotensin II, a potent is_associated_with::vasoconstrictor in a substrate concentration-dependent manner.
 * ACE degrades is_associated_with::bradykinin, a potent is_associated_with::vasodilator, and other vasoactive peptides,

These two actions make ACE inhibition a goal in the treatment of conditions such as high blood pressure, is_associated_with::heart failure, is_associated_with::diabetic nephropathy, and is_associated_with::type 2 diabetes mellitus. Inhibition of ACE (by is_associated_with::ACE inhibitors) results in the decreased formation of angiotensin II and decreased metabolism of is_associated_with::bradykinin, leading to systematic dilation of the arteries and veins and a decrease in arterial blood pressure. In addition, inhibiting angiotensin II formation diminishes angiotensin II-mediated is_associated_with::aldosterone secretion from the is_associated_with::adrenal cortex, leading to a decrease in water and sodium reabsorption and a reduction in is_associated_with::extracellular volume.

Genetics and C and N domains function
The ACE gene, ACE, encodes two is_associated_with::isozymes. The somatic isozyme is expressed in many tissues, mainly in the lung, including vascular endothelial cells, epithelial is_associated_with::kidney cells, and testicular is_associated_with::Leydig cells, whereas the germinal is expressed only in sperm. Brain tissue has ACE enzyme, which takes part in local RAAS and converts Aβ42 (which aggregates into plaques) to  Aβ40 (which is thought to be less toxic) forms of is_associated_with::beta amyloid. The latter is predominantly a function of N domain portion on the ACE enzyme. ACE inhibitors that cross the blood–brain barrier and have preferentially select N terminal activity may, therefore, cause accumulation of Aβ42 and progression of dementia.

Pathology

 * Elevated levels of ACE are found in is_associated_with::sarcoidosis, and are used in diagnosing and monitoring this disease. Elevated levels of ACE are also found in is_associated_with::leprosy, is_associated_with::hyperthyroidism, acute is_associated_with::hepatitis, is_associated_with::primary biliary cirrhosis, is_associated_with::diabetes mellitus, is_associated_with::multiple myeloma, is_associated_with::osteoarthritis, is_associated_with::amyloidosis, is_associated_with::Gaucher disease, is_associated_with::pneumoconiosis, is_associated_with::histoplasmosis, is_associated_with::miliary tuberculosis.
 * Serum levels are decreased in is_associated_with::renal disease, is_associated_with::obstructive pulmonary disease, and is_associated_with::hypothyroidism.

Influence on athletic performance

 * ACE gene is a I/D polymorphism leading to the presence(I) or absence (D) the carriers of the ACE insertion allele of an alu repeat in intron 16 of the gene. With the insertion, observed higher maximum oxygen uptake (VO2max), increase in training, and increased muscle when paired with individuals carrying the deletion allele.
 * Individuals with the insertion are associated with long distance and endurance events. This is seen in studies that suggest that it is due to lower levels of angiotensin II. The deletion of the Alu increases angiotensin II that in turn increases the vasoconstriction of blood vessels. This is observed in short distance events and seen mostly in swimmers.