Hyaluronidase
A collection of definitions.
hy·a·lu·ron·i·dase (hī'ə-lʊ-rŏn'ĭ-dās', -dāz') noun.
An enzyme that catalyzes the breakdown of hyaluronic acid in the body, thereby increasing tissue permeability to fluids. Also called spreading factor.
Any one of a family of enzymes, also known as hyaluronate lyases or spreading factors, produced by mammals, reptiles, insects, and bacteria, which catalyze the breakdown of hyaluronic acid, a complex polysaccharide.
Some hyaluronidases also attack other similar polysaccharides.
Since all liquefy the polysaccharide gel which fills the tissue spaces, they effectively accelerate diffusion so that injected, dissolved, or particulate matter (bacteria, viruses, toxins, or pigments) can diffuse through a larger volume of tissue.
Enzyme that degrades hyaluronic acid (a glycosaminoglycan extracellular matrix constituent).
Any of three enzymes that catalyze the hydrolysis of hyaluronic acid, thus increasing tissue permeability to fluids. One or more of these enzymes occur in the testes and in spermatozoa.
Hyaluronidase
The hyaluronidases (EC 3.2.1.35) are a family of enzymes that degrade hyaluronic acid.
By catalyzing the hydrolysis of hyaluronic acid, a major constituent of the interstitial barrier, hyaluronidase lowers the viscosity of hyaluronic acid, thereby increasing tissue permeability.
It is, therefore, used in medicine in conjunction with other drugs in order to speed their dispersion and delivery.
The most common application is in ophthalmic surgery, in which it is used in combination with local anesthetics.
Some bacteria, such as Staphylococcus aureus, Streptococcus pyogenes, and Clostridium perfringens, produce hyaluronidase as a means for greater mobility through the body's tissues and as an antigenic disguise that prevents their being recognized by phagocytes of the immune system.
In human fertilization, hyaluronidase is released by the acrosome of the sperm cell after it has reached the oocyte, by digesting proteins in the zona pellucida, thus enabling conception.
(Hyaluronate 4-glycanohydrolase; EC 3.2.1.36 ) Hyaluronidase catalyzes the depolymerization of mucopolysaccharides, hyaluronic acid, and the chondroitin sulfates A and C.
The enzyme is widely distributed in animal tissues but is found in great concentrations in the bovine and ovine testes. It is also produced by a number of bacteria. Hyaluronidase from bovine testes has a molecular weight of 55,000. Purified hyaluronidase is used clinically for the intradermal administration of large volumes of fluid when intravenous injections are contraindicated.
The enzyme is administered prior to or simultaneously with the fluid and it facilitates absorption of the fluid (Human Biochemistry; Orten, J.M., and Neuhaus, O.W.; 10th edition, Pg. 411, 1982. Mosby, St. Louis).
A mucolytic enzyme that facilitates the spread of fluids through tissues by lowering the viscosity of hyaluronic acid
The function of this enzyme is to catalyze the depolymerization of mucopolysaccharides, hyaluronic acid, and the chondroitin sulfates A and C.
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In 1880, the French chemist Portes first reported that the mucin in the vitreous body, which he named hyalomucine, behaved differently from other mucoids in cornea and cartilage. Fifty-four years later, Meyer and Palmer isolated a new polysaccharide from the vitreous which they named hyaluronic acid.
Hyaluronan (HA) as it is now known, is a polyanionic polysaccharide chemically classified as a glycolsaminoglycan that consists of N-acetyl-D-glucosamine and β-glucoronic acid. It is most correctly referred to as hyaluronan because it exists in vivo as a polyanion and not in the protonated acid form. HA is distributed widely in vertebrates as a component of the cell coat of many strains of bacteria.1 Initially the main functions of HA were believed to be mechanical as it has a protective, structure stabilizing and shock-absorbing role in the body. However, more recently the role of HA in the mediation of physiological functions via interaction with binding proteins and cell surface receptors including morphogenesis, regeneration, would healing, and tumor invasion, as well as in the dynamic regulation of such interactions on cell signaling and behavior has been documented. The unique viscoelastic nature of hyaluronan along with its biocompatibility and nonimmunogenicity has led to its use in a number of cosmetic, medical, and pharmaceutical applications. More recently, HA has been investigated as a drug delivery agent for ophthalmic, nasal, pulmonary, parenteral, dermal and oral routes.
The precise chemical structure of HA, which comprises repeating units of D-glucoronic acid and N-acetyl-D-glucosamine, was first determined by Weissman and Meyer (1954). The molecular weight is generally within the range of 50,000 to 8,000,000 Daltons, depending on the source, method of isolation, and method of determination. Further studies have shown the primary structures of the polysaccharide to be an unbranched linear chain with the monosaccharides linked together through alternating β1,3 and β1,4 glycosidic bonds.1,2,3
HA and its associated networks have many physiological roles that include tissue and matrix water regulation, structural and space-filling properties, lubrication, and a number of macromolecular functions.4
HA is found in almost all vertebrate organs, but most abundantly in the extracellular matrix of soft connective tissues. It is particularly abundant in mammalian skin where it constitutes a high fraction of the extracellular matrix of the dermis.5,6
Under normal physiological conditions, HA is one of the principal components of synovial fluid present at concentrations between 1.4-4 mg/ml.7 The viscoelasticity of the HA matrix is responsible for conferring lubrication and mechanical support to joints. However, the molecular weight of HA in osteoarthritic or inflamed joints can decline to 0.5 million Daltons (from 4-5 million Daltons in the normal joints) as a result of the presence of proinflammatory cytokines, free radicals, and proteinases. In addition, the membrane permeability of the synovial vasculature increases in response to inflammation or injury, leading to increases in the infiltration of plasma fluids and in turn decreases in concentration of HA in the joints. The decrease in the concentration and/or the molecular weight of HA can result in changes in the viscoelasticity of the synovial fluid, leading to joint dysfunction.
There are more things in heaven and earth, Horatio, than are dreamt of in your philosophy.
William Shakespeare,
"Hamlet", Act 1 scene 5
English dramatist & poet (1564 - 1616)
