Pancreatic juice cholesterol esterase

Hyun, Jin Hai; Treadwell, C. R.; Vahouny, George V.

doi:10.1016/0003-9861(72)90211-1

Cited by 53 publications

(23 citation statements)

References 21 publications

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“…But when they are lipid-soluble, such as cholesteryl esters, only primary bile salts are activators even if secondary bile salts can play an important role in the solubilization of the substrates [3]. This specific activation involves the polymerization of the enzyme since a hexamer is the active form of the rat cholesterol esterase [21] and a dimer is the active form of the human carboxylic-ester hydrolase acting on cholesterol esters [3]. Nevertheless this is not the case for porcine cholesterol esterase, which is active in the absence of bile salts [12].…”

Section: Discussionmentioning

confidence: 99%

“…Thus micelles could protect only the specific site, since monomers of taurodeoxycholate protect the unspecific site. This possible protection of the specific site by micelles invalidates the stoichiometry of the cholesterol-esterase -bile-salt complex [21], which comprises six enzyme molecules for three bile salt molecules. Since the bile salt molecule is asymmetrical, the specific site would have to be different on the two enzyme molecules forming the active human dimer [3].…”

Section: The Dimerization Stoichiametry and Effect On The Unspecific mentioning

confidence: 99%

“…While carboxylic-ester hydrolases are activated by all bile salts, cholesterol-ester hydrolases are only activated by primary bile salts [I, 21. In a recent study we have demonstrated that the pancreatic activities on soluble carboxylic esters and on cholesteryl esters were due, at least in the human pancreatic juice, to a single enzyme.…”

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confidence: 99%

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On the Probable Involvement of Arginine Residues in the Bile‐Salt‐Binding Site of Human Pancreatic Carboxylic Ester Hydrolase

Lagadic‐Gossmann¹,

Campése²,

Multigner³

et al. 1983

European Journal of Biochemistry

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Modification of arginine residues with 2,3-butanedione inhibits the carboxylic-ester hydrolase activity on soluble and emulsified substrates when assayed with bile salts. The a-dicarbonyl reagent modifies seven of the nineteen arginine residues present per enzyme molecule. Nevertheless the inactivation with butanedione is greatly diminished when the protein is in the presence of negatively charged micellar bile salt. In these conditions we observe the protection of one arginine residue by sodium taurodeoxycholate and of two arginine residues by sodium cholate. This suggests that the carboxylic-ester hydrolase from human pancreatic juice contains at least two arginine residues essential for the activation by bile salts. All our data confirm the presence of two bile-salt-binding sites on the enzyme in which one arginine per site is involved and plays the general role of an anionic binding site. This study provides evidence that arginine residues may play an essential role in the interaction between bile salts and protein.For many years the distinction between the pancreatic carboxylic-ester hydrolase and the pancreatic cholesterol-ester hydrolase was based not only on the substrate specificity but also on the bile-salt effect. While carboxylic-ester hydrolases are activated by all bile salts, cholesterol-ester hydrolases are only activated by primary bile salts [I, 21. In a recent study we have demonstrated that the pancreatic activities on soluble carboxylic esters and on cholesteryl esters were due, at least in the human pancreatic juice, to a single enzyme. This enzyme seems also to be responsible for the lipid-soluble-vitaminsesters hydrolase, non-specific lipase and lysophospholipase activities of human pancreatic juice [3, 41. Because of its large specificity we have called this enzyme carboxylic-ester hydrolase.We have recently postulated the presence of two bile-saltbinding sites on the human pancreatic carboxylic-ester hydrolase [3]. One of these, (site SP in Fig. 1) would be specific for the 3a and 7a-hydroxylated positions of cholanic acid (primary bile salts). It would promote the dimerization and consequently the activity of the enzyme on hydrophobic substrate (CE) after bile-salt solubilization. The second site (site U, Fig. 1) would be non-specific for the hydroxyl positions of bile salts and would be located at (or near) the active center (site C, Fig. 1) of the carboxylic-ester hydrolase. This enzyme shows a poor activity on water-soluble substrates. Nevertheless, the interaction of bile salts, primary or secondary with the unspecific site, U, gives a more effective enzyme [I, 51 probably by inducing a modification in the active site of the enzyme. Interestingly, in a recent paper it has been suggested [6] that the phospholipase A2 from cobra venom has two kinds of functional sites: an activator site and a catalytic site, showing some analogy with the pancreatic carboxylic-ester hydrolase. From the scheme presented in This work has been carried out in an attempt to answer these questions, at least...

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Section: Discussionmentioning

confidence: 99%

Section: The Dimerization Stoichiametry and Effect On The Unspecific mentioning

confidence: 99%

See 1 more Smart Citation

On the Probable Involvement of Arginine Residues in the Bile‐Salt‐Binding Site of Human Pancreatic Carboxylic Ester Hydrolase

Lagadic‐Gossmann¹,

Campése²,

Multigner³

et al. 1983

European Journal of Biochemistry

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“…For example, taurocholate has been shown to increase the sensitivity of pancreatic neutral CEH enzyme to phenylmethylsulfonyl fluoride (PMSF), an inhibitor ofenzymes requiring free serine hydroxyl groups for activity (15). When oocyte supernatants were incubated with PMSF prior to addition of cholate and incubation with cholesteryl oleate substrate, 1 and 2 mM PMSF caused 25% and 66% inhibition of CEH activity, respectively.…”

Section: Introductionmentioning

confidence: 99%

Expression in Xenopus oocytes of rat liver mRNA coding for a bile salt-dependent cholesteryl ester hydrolase.

Zolfaghari¹,

Harrison²,

Ross³

et al. 1989

Proc. Natl. Acad. Sci. U.S.A.

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“…Thus the total amount of 0-turns may reach about 20 of the secondary structure. [14] lipase [15] ~ ~~ residues/mol [12] with a set of p-turns of different types 1i.e. poly(Ala~-Gly2), L-Pro-D-Ala, N-acctyl-Pro-Gly-Leu-OH)] : 43 ,&pleated sheets, 7 ; < /3-turns I, 4 '>A 0-turns 11, 9…”

Section: Circular Dichroismmentioning

confidence: 99%