Phospholipase phospholipids

Choline-containing phospholipids Phospholipase D Choline oxidase 51... 

Phospholipids Phospholipase/choline oxidase Catalase (increases stability of main en2yme)... 

The phosphoric acid esters of diacyl glycerides, phospholipids, are important constituents of cellular membranes. Lecithins (phosphatidyl cholines) from egg white or soybeans are often added to foods as emulsifying agents or to modify flow characteristics and viscosity. Phospholipids have very low vapor pressures and decompose at elevated temperatures. The strategy for analysis involves preliminary isolation of the class, for example by TLC, followed by enzymatic hydrolysis, derivatization of the hydrolysis products, and then GC of the volatile derivatives. A number of phospholipases are known which are highly specific for particular positions on phospholipids. Phospholipase A2, usually isolated from snake venom, selectively hydrolyzes the 2-acyl ester linkage. The positions of attack for phospholipases A, C, and D are summarized on Figure 9.7 (24). Appropriate use of phospholipases followed by GC can thus be used to determine the composition of phospholipids. 

Cholesterol Esters Cholesterol esterase Phospholipids Phospholipase 2 Phospholipase 1 Lysophospholipase... 

The hydrolysis of glycerophospholipids ester bonds are regulated by a group of enzymes namely phospholipases. The site of action of every phospholipase is specific for every enzyme and is of great importance for the biological role of the phospholipids. Phospholipase A2 for example stereospeciftcally catalyzes the hydrolysis of xn-2 acyl ester bond, and plays an important role in the lung inflammation pathogenesis Fig. (5) LU5]. 

Keywords Phospholipids, Phospholipases, Transphosphatidylation, Organic phosphates, Diacylglycerol. 

Phospholipases are enzymes that cleave phospholipids. Phospholipases of type Al, A2, C and D are differentiated according to the specificity of the attack point on the phospholipid. The bonds cleaved by these phospholipases are shown in Fig. 5.28a. 

It has been indicated that the phosphodiesteratic cleavage of the Inositol phospholipids (phospholipase C activity) precedes and might trigger the activation of phospholipase A2 in stimulated platelets.1l >20,21 It seems that some of the products formed during the phosphodiesteratic cleavage of the inosltides could be related to Ca2+ mobilization. One of these products, myoinositol 1,4,5-trisphosphate. 

Cho, Y., and Ziboh, V.A. (1994) Incoiporation of 13-Hydroxyoc-tadecadienoic Acid (13-HODE) into Epidermal Ceiamides and Phospholipids Phospholipase C-Catalyzed Release of Novel 13-HODE-Containing Diacylglycerol, J. UpidRes. 35,255—262. 

Figure 9. Arrhenius plot of reaction rates in the range of 20 0-—18 C. Panel a represents the phospholipid-phospholipase system panel b, the triglyceride-lipase system, (reprinted from rf. 27)...

GPC and GPE are the hydrolytic products of the major membrane phospholipids, phosphatidylcholine and phosphatidylethanolamine, respectively. The enzymes responsible for the degradation of these phospholipids, phospholipase A, and Aj, are present in human muscle. Hereditary muscular dystrophy, a lethal disease of young children, is generally assumed to be a membrane disease (Rowland, 1980). Therefore, P-NMR studies on... 

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