Recherches sur la caséine VI. Sur la transformation de la caséine en paracaséine

Cherbuliez, Emile; Baudet, P.

doi:10.1002/hlca.19500330635

Cited by 31 publications

(3 citation statements)

References 16 publications

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“…Although the interpretation of these experiments is complicated by the unexpected similarity in the effects of low and high ligation of the bile duct and to some extent by variable recoveries of enzyme activity, we conclude that part ofthe peptidase activity in the brush border is attributable to pancreatic proteases, of which chymotrypsin and elastase are probably implicated. The coagulation of milk by the enzyme rennin (EC 3.4.4.3) is considered to be a two-stage process (Cherbuliez & Baudet, 1950). During the primary phase K-casein is hydrolysed by the enzyme (Waugh & Hippel, 1956;Wake, 1959) and then in the presence of Ca2+ the casein micelles are precipitated (Pyne, 1953).…”

Section: Aparicio (Departments Of Biochemistry and Pathology Univermentioning

confidence: 99%

The presence of pancreatic proteases in particulate preparations of rat intestinal mucosa

Woodley

Kenny

1969

Biochemical Journal

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We have previously reported that a neutral peptidase capable of hydrolysing [1251]iodinated insulin B chain (pH7-5 peptidase) is, like arylamidase and alkaline phosphatase, localized in the microvilli of the proximal renal tubule. Moreover, electron micrographs of negatively stained preparations have revealed that the surface of the microvillus has a covering of discrete granules 80-1001 in diameter (Wong-Leung, George, Aparicio & Kenny, 1968). It is also clear that the pH7.5 peptidase is readily distinguishable from arylamidase in properties and substrate specificity (Kenny, Wong-Leung & Ingram, 1968). We now report some further experiments concerned with the localization of these enzymes in the microvillus and with the purification of the arylamidase.Deoxycholate treatment of a light-microsomal fraction of the kidney cortex disrupted all the membranous elements and solubilized both the pH7*5 peptidase and arylamidase to about the same extent. On the other hand, incubation of the fraction with papain brought about the selective release of arylamidase in a soluble form, while the pH7-5 peptidase and alkaline phosphatase remained in the microsomal pellet. Electron micrographs of the pellets, negatively stained with phosphotungstate, were examined. After papain treatment the surface of many microvilli appeared smooth, in contrast with the control (which had been incubated without papain) in which the surface covering of particles was preserved.The supernatant fraction obtained after papain treatment provided a useful starting point for the purification of arylamidase. Ammonium sulphate precipitation, DEAE-cellulose chromatography and column electrophoresis in a sucrose density gradient yielded a preparation with a specific activity of 57 units/mg. (1 unit-1 ,umole of L-leucine pnitroanilide hydrolysed/min. at 370 at pH7.0) and which appeared to be homogeneous on disc electrophoresis. This preparation also hydrolysed L-aamino acid P-naphthylamides, the relative rates for leucine, arginine and glutamic acid derivatives being 100: 70:28. lodinated insulin B chain was attacked about 1000 times more slowly than was L-leucine fl-naphthylamide. Studies in the analytical ultracentrifuge using the sedimentation-equilibrium method of Yphantis (1964) gave a mol.wt. of 136 000 + 13 000.Our results indicate that alkaline phosphatase and the pH7*5 peptidase are situated within the microvillus and that arylamidase is located superficially. The results obtained from the electron microscope and the ultracentrifuge are consistent with the hypothesis that arylamidase is associated with the surface particles. During a study of peptidases of the intestinal brush border of the rat we observed that the hydrolysis of [125I]iodinated insulin B-chain at pH7-5 by a crude brush-border preparation was sensitive to inhibition by di-isopropyl phosphorofluoridate. This finding raised two possibilities: either the mucosa contained a serine peptidase of intestinal origin or it was contaminated with a serine peptidase derived from the pancreatic j...

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Section: Aparicio (Departments Of Biochemistry and Pathology Univermentioning

confidence: 99%

The presence of pancreatic proteases in particulate preparations of rat intestinal mucosa

Woodley

Kenny

1969

Biochemical Journal

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“…The coagulation of milk by the enzyme rennin (EC 3.4.4.3) is considered to be a two-stage process (Cherbuliez & Baudet, 1950). During the primary phase K-casein is hydrolysed by the enzyme (Waugh & Hippel, 1956;Wake, 1959) and then in the presence of Ca2+ the casein micelles are precipitated (Pyne, 1953).…”

Section: )mentioning

confidence: 99%

Action of rennin on heat-sterilized milk

Hindle

Wheelock

1969

Biochemical Journal

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“…It has been suggested that the /c-casein fraction of whole-casein is associated exclusively with the a-casein. Cherbuliez & Baudet (1950) and Alais, Mocquot, Nitschmann & Zahler (1953) even concluded that only a-casein is altered by rennin, whereas j8-and y-casein are not attacked but are merely co-precipitated unchanged along with the altered a-casein in the presence of Ca ++ . In this connexion, however, it should be noted that the definition of y-casein is not precise.…”

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Action of rennin on α-, β- and γ-caseins

Lahav¹,

Babad²

1964

Journal of Dairy Research

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SummaryWhole acid casein and α-, β- and γ-caseins were isolated and treated with rennin. Chemical, chromatographical and electrophoretical analyses were done on the caseins and on the products obtained from them after rennin treatment. Three different fractions were obtained which had some specific protective activity for the Ca-sensitive forms of α-, β- and γ-casein, respectively, and which differed in their chemical, chromatographical, and electrophoretical properties.It is suggested that each casein fraction in milk is associated with its own protective fraction which when released by the action of rennin, allows the casein to clot.

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Recherches sur la caséine VI. Sur la transformation de la caséine en paracaséine

Abstract: Volumen XXXIII, Fasciculus VI (1950) -So. 215-216.Les fractions para a, impures sont rbunies, dissoutes B 0,3% au p H 6, additionnees de sulfate d'ammonium B , u = 2,2 e t la solution est port6e B 30"

Cited by 31 publications

References 16 publications

The presence of pancreatic proteases in particulate preparations of rat intestinal mucosa

The presence of pancreatic proteases in particulate preparations of rat intestinal mucosa

Action of rennin on heat-sterilized milk

Action of rennin on α-, β- and γ-caseins

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