Azurocidin also known as cationic antimicrobial protein CAP37 or heparin-binding protein (HBP) is a

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...

that in humans is encoded by the ''AZU1''

gene In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...

Function

Azurophil granule An azurophilic granule is a cellular object readily stainable with a Romanowsky stain. In white blood cells and hyperchromatin, staining imparts a burgundy or merlot coloration. Neutrophils in particular are known for containing azurophils l ...

s, specialized

lysosome A lysosome () is a membrane-bound organelle found in many animal cells. They are spherical vesicles that contain hydrolytic enzymes that can break down many kinds of biomolecules. A lysosome has a specific composition, of both its membrane prot ...

s of the

neutrophil Neutrophils (also known as neutrocytes or heterophils) are the most abundant type of granulocytes and make up 40% to 70% of all white blood cells in humans. They form an essential part of the innate immune system, with their functions varying in ...

, contain at least 10 proteins implicated in the killing of microorganisms. The protein encoded by this gene is an azurophil granule antimicrobial protein, with monocyte chemotactic and antibacterial activity. It is also an important multifunctional

inflammatory mediator Inflammation (from la, inflammatio) is part of the complex biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or irritants, and is a protective response involving immune cells, blood vessels, and molec ...

. The genes encoding this protein, neutrophil elastase 2, and proteinase 3 are in a cluster located at chromosome 19pter. All 3 genes are expressed coordinately and their protein products are packaged together into azurophil granules during neutrophil differentiation.

Structure

This encoded protein is a member of the PA clan of proteases but it is not a serine proteinase, because the active site serine and histidine residues are replaced, making it a

pseudoenzyme Pseudoenzymes are variants of enzymes (usually proteins) that are catalytically-deficient (usually inactive), meaning that they perform little or no enzyme catalysis. They are believed to be represented in all major enzyme families in the kingdo ...

Clinical significance

In patients with fever, high plasma levels of HBP indicates that the patient is at high risk of developing

sepsis Sepsis, formerly known as septicemia (septicaemia in British English) or blood poisoning, is a life-threatening condition that arises when the body's response to infection causes injury to its own tissues and organs. This initial stage is follo ...

with

circulatory collapse Shock is the state of insufficient blood flow to the tissues of the body as a result of problems with the circulatory system. Initial symptoms of shock may include weakness, fast heart rate, fast breathing, sweating, anxiety, and increased thi ...

Function

Structure

Clinical significance

References

External links

Further reading