Lecithinases

Lecithins are complex phospholipids and occur in serum and egg yolk. Enzyme activity breaks down the emulsion and liberates free fats so that turbidity is created. The test is used for distinguishing Clostridium species and may be carried out using commercially available egg yolk suspensions. 

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The second type of material includes spores, which may or may not produce disease symptoms but which can germinate in the insect gut and give rise to vegetative bacterial cells which in turn may produce, and exoenzymes such as phospholipases (lecithinases) or hyaluronidase. The phospholipases may produce direct toxic symptoms owing to their action on nervous or other phospholipid-containing tissue. Hyaluronidase breaks down hyaluronic acid and produces effects on animal tissue which are morphologically similar to the breakdown of insect gut wall in the presence of microbial insecticide preparations. 

Lecithinase is produced by Clostridium perfringens. This is a calcium-dependent lecithinase whose activity depends on the ability to split lecithin. Since lecithin is present in the membrane of many different kinds of cells, damage can occur throughout the body. Lecithinase causes the hydrolysis of erythrocytes and the necrosis of other tissue cells. 

ZENECA has developed a non-solvent based recovery process as an alternative to solvent extraction for the commercial production of poly(3HB) and poly(3HB-co-3V) by A. eutrophus [94,95], In this process the cells were first exposed to a temperature of 80 °C and subsequently treated with a cocktail of various hydrolytic enzymes consisting of lysozyme, phospholipase, lecithinase, the proteinase alcalase, and others. Most of the cellular components were hy-... 

This enzyme [EC 3.1.1.5] (also referred to as lecithinase B, lysolecithinase, and phospholipase B) catalyzes the hydrolysis of a 2-lysophosphatidylcholine to produce glycerophosphocholine and a fatty acid anion. 

This zinc-dependent enzyme [EC 3.1.4.3] (also known as lipophosphodiesterase I, lecithinase C, Clostridium welchii ce-toxin, and Clostridium oedematiens 13- and y-toxins) catalyzes the hydrolysis of a phosphatidylcholine to produce 1,2-diacylglycerol and choline phosphate. The enzyme isolated from bacterial sources also acts on sphingomyelin and phosphatidylinositol however, the enzyme isolated from seminal plasma does not act on phosphatidylinositol. See Micelle... 

In 1954, Beaufay and de Duve (27) first suggested a relationship between microsomal phospholipid and glucose-6-phosphatase. They observed a loss of enzymic activity from phospholipid-rich microsomal preparations concomitant with extraction with such organic solvents as butanol or treatment with lecithinase. Various studies were carried out to demonstrate that the latter effect was not produced through inhibition of enzymic activity by accumulated products of the hydrolysis of phospholipids. On the basis of their observations that deoxycholate treatment labilized microsomes to phospholipase action, they concluded that . . . the detergent did not exert its primary effect on the dissociation of phospholipids from microsomal protein, but that it probably disrupted... 

The effect of various snake venoms on surface films of lecithin is to remove one of the long-chain fatty-acid groups from the molecule, causing a considerable fall in surface potential 3 this reaction is much slowed by compression of the film as the result of compression is to remove the double bonds in the oleyl group (the one split off) of the lecithin from the surface, it is possible that the lecithinase, the enzyme which splits off the oleyl group, has a molecular structure which fits both the end group and the double bond in the lecithin. 

Stone, M.J. 1952b. The action of lecithinase of Bacillus cereus on the globule membrane of milk fat.. / Dairy Res. 19, 311-315. 

Owens, J.J. 1978a. Lecithinase positive bacteria in milk. Process Biochem. 13(1), 13-14, 30. 

Owens, J.J. 1978b. Observations on lecithinases from milk contaminants. Process Biochem. 13(7), 10, 12, 18. 

Vogel, W.C. and Bierman, E.L. Evidence for in vivo activity of postheparin plasma lecithinase in man. Proc. Soc. 

Lipophosphodiesterase I. Lecithinase C. Clostridium welchii alpha-toxin. Clostridium oedematiens beta- and gamma-toxins. 

Lipophosphodiesterase II. Lecithinase D. Choline phosphatase. A phosphatidylcholine + H(2)0 = choline + a phosphatidate. 

Since the observation by McFarlane and Knight (1941) that lecithinase C promotes hydrolysis of phospholipids with subsequent liberation of lipids from lipoproteins, it has been postulated that phospholipids play a role in maintaining the structural integrity of lipoproteins. This seems to be supported by the studies of Krumwiede (1958), who employed lecithinase C in horse serum a-lipoprotein, and by Ashworth and Green (1963b, c), who used phospholipase D on human a-Iipoproteins. Splitting of HDL was observed in both instances. Ashworth and Green (19 b, c)... 

As with other lipolytic enzymes, this enzyme has appeared under several different names in the literature. Contardi and Ercoli (1933) proposed the name lecithinase C, and subsequently phospholipase C was used. Because the enzyme (E.C. 3.1.4.3) which hydrolyzes the glycerol-phosphate bond in phospholipids was also called phospholipase C, the term phospholipase D was introduced for the plant enzyme and is the commonly used name at present. Brockerhoff and Jensen (1974) have proposed that the letters. A, B, C, and D be dropped in phospholipase nomenclature for phospholipase D, they have used the term phospholipase-4 and linked this with cerami-dase. The present discussion will retain the D nomenclature, since all the literature published since 1974 has used this form. 

Phospholipase A2 Lecithinase A Phosphatide 2-acyl-hydrolase 3.1.1.4 Pancreas and small intestine Lecithins and cephalins... 

Lecithinase A is an enzyme that hydrolyses the bond linking the fatty acid to the 3-hydroxyl group of lecithin (see p. 45). The product formed from this hydrolysis, lysolecithin, is further hydrolysed by lysolecithinase (lecithinase B) to form glyc-erolphosphocholine and a fatty acid. Cholesterol esterase catalyses the splitting of cholesterol esters. 

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