From the INSERM -U476 Nutrition Humaine et Lipides, 18 Avenue Mozart 13009 Marseille, France and the § Laboratoire LAPHAL-BP7-13718 Allauch cedex, France
Received for publication, November 14, 2000, and in revised form, December 19, 2000
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ABSTRACT |
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In vertebrates, dietary fat digestion mainly
results from the combined effect of pancreatic lipase, colipase, and
bile. It has been proposed that in vivo lipase adsorption
on oil-water emulsion is mediated by a preformed lipase-colipase-mixed
micelle complex. The main lipase-colipase binding site is located on
the C-terminal domain of the enzyme. We report here that in
vitro the isolated C-terminal domain behaves as a potent
noncovalent inhibitor of lipase and that the inhibitory effect is
triggered by the presence of micelles. Lipase inhibition results from
the formation of a nonproductive C-terminal domain-colipase-micelle ternary complex, which competes for colipase with the active
lipase-colipase-micelle ternary complex, thus diverting colipase from
its lipase-anchoring function. The formation of such a complex has been
evidenced by molecular sieving experiments. This nonproductive complex
lowers the amount of active lipase thus reducing lipolysis.
Preliminary experiments performed in rats show that the
C-terminal domain also behaves as an inhibitor in vivo and
thus could be considered a potential new tool for specifically reducing
intestinal lipolysis.
In vertebrates, the digestion of dietary triacylglycerols,
although initiated in the upper part of the digestive tract by preduodenal lipases, is driven to completion in the intestine by the
combined effects of pancreatic lipase (EC 3.1.1.3), colipase, and bile
secretion. Intestinal lipolysis proceeds through an heterogeneous catalysis involving a lipase activation step that requires the presence
of pancreatic colipase to circumvent the inhibitory effect of natural
amphiphilic compounds. In the intestine, these compounds are coating
the oil/water interface thus impeding lipase adsorption on its
substrate. The primary function of colipase is, therefore, to anchor
lipase on its substrate in the presence of amphiphiles.
Pancreatic lipase is made up of a single polypeptide chain folded in
two domains (1, 2). The N-terminal domain (residues 1-336) bears the
catalytic triad, which is buried underneath a surface loop (the flap)
controlling the access of substrate. The C-terminal domain (residues
337-449) is mainly devoted to colipase binding (3-5). The
understanding of the activation process has progressed dramatically
thanks to the resolution of several three-dimensional structures of
both lipase and lipase-colipase complexes (1, 2, 5, 6). The motion of
the flap from a closed (inactive conformation) to an open (active
conformation) position unmasks the active site that consequently adopts
the catalytically active configuration. Recently, Hermoso et
al. (7) proposed that in vivo lipase activation results
from the formation in solution of a ternary complex involving lipase,
colipase, and a mixed bile lipid micelle. The complex represents the
functional unit able to bind the emulsified oil droplets and to perform
catalysis. The micelle is located in a cavity delineated by the
C-terminal domain and colipase. Although mainly interacting with the
concave face of colipase, the disc-shaped micelle is also in close
contact with several segments of the lipase C-terminal domain. Thus,
the strengthening of the interactions between lipase and colipase observed in the presence of micelles (7, 8) mainly occurs via the C-terminal domain of lipase.
In this paper, we investigate a new strategy to regulate
specifically the pancreatic lipase activity based on the ability of the
isolated C-terminal domain of lipase to behave as a functional entity
toward colipase binding (9). We demonstrated that in vitro
this domain behaves as a specific inhibitor of pancreatic lipase under
conditions approximating the physiological ones. We also report
preliminary results indicating that the C-terminal domain is able to
significantly reduce lipolysis in vivo in rats.
Taurodeoxycholic acid
(NaTDC),1 glycocholic acid,
glycochenodeoxycholic acid, glycodeoxycholic acid, taurocholic acid,
taurochenodeoxycholic acid, oleic acid,
L- Purification of Porcine Pancreatic Lipase, Colipase, and Lipase
C-terminal Domain--
Porcine pancreatic lipase and colipase were
purified from a pancreatic powder as previously described in Refs. 10
and 11, respectively. The C-terminal domain was obtained by limited
proteolysis of porcine lipase as reported in Ref. 9. Protein
concentrations were determined at 280 nm using a molecular extinction
coefficient ( N-terminal Sequence Analysis--
N-terminal sequence analyses
were performed by stepwise Edman degradation using a gas phase
sequencer (Applied Biosystems, model 470A). The resulting
phenylthiohydantoin-derivative amino acids were analyzed by high
performance liquid chromatography using a C18 column
(Brownlee, 5 µm, 220 × 2.1 mm inner diameter). They were eluted
using a gradient from 10 to 46% methanol in 7 mM sodium
acetate buffer, pH 4.84.
Mass Spectrometry--
MALDI-MS was performed on a reflection
time-of-flight mass spectrometer equipped with delayed extraction
(Voyager DE-RP, Perceptive Biosystems Inc.). The sample was first
dissolved in 10 µl of acetic acid and then diluted with 90 µl of
water. From this sample, 0.7 µl (about 4 picomoles) was directly
mixed on the support with an equal volume of sinapinic matrix
(saturated solution of sinapinic acid solution in 40% acetonitrile,
60% water, made 0.1% in trifluoroacetic acid). Analysis was conducted
in linear mode using apomyoglobin as calibrant.
Fractionation by Gel Filtration of the Different Molecular
Species--
Molecular sieving experiments were performed on an
Ultrogel Aca54 column (90 × 1 cm) equilibrated in 20 mM Tris-HCl buffer, pH 7.5 containing 0.1 M
NaCl and 1 mM benzamidine in the presence or in the absence
of 4 mM NaTDC. Blue dextran at a concentration of 1 mg/ml
was used to determine the void volume of the column. The flow rate was
6 ml/h. The volume of the fractions was 0.8 ml. The fractions were
analyzed by either 12 or 15% SDS-PAGE according to Laemmli (12). To
normalize data, the Kav values were calculated according to the equation, Kav = (Ve Lipase Activity Measurements--
Lipase activity was
potentiometrically determined at 25 °C using either 0.11 M emulsified tributyrin, pH 7.5 or 10 mM
triolein, pH 8.5 in the presence of colipase. The lipase and colipase
concentrations were in the range of 10 In Vivo Experiments--
Adult male Wistar rats (Iffo-Credo,
l'Arbresle, France) weighing 250-300 g were housed in wire-bottomed
cages in an air-conditioned room with a 12-h light/12-h dark cycle.
Water and food were supplied ad libidum for a week. Then,
the rats were starved for 24 h before the experiment with only
water ad libidum. Thereby, rat stomachs were free of any material.
In a first step of experiments, two groups of rats (n = 10, each) were orally given 1.5 ml of a liquid test meal consisting of
a lipid emulsion containing triolein, cholesterol, lecithin (90% pure,
from Lipoid (FRG), albumin, sucrose, and NaCl prepared in
phosphate-buffered saline, pH 7.2 (Sigma, Table
I).
[carboxyl-14C]Triolein (4.13 GBq/mmol, 98%
pure) was used to quantify the extent of lipolysis by measuring the
total radioactivity associated with mono, di, and triolein.
For the test group of rats, 1 mg of porcine C-terminal domain in 0.5 ml
of water was added to the meal. For the control group, 0.5 ml of water
was added to the meal. After 3.5 h of digestion, the rats were
anesthetized with diethyl ether and then killed by total
exsanguination. The small intestine was rapidly removed, and its
content was collected on ice by flushing with 10 ml of ice-cold 2 mM sodium taurocholate. After acidification with HCl to
inactivate pancreatic lipase and homogenization with a Potter homogenizer, 1-ml aliquots were taken for radioactivity determination. The mucosa of each intestinal segment was scraped on ice and acidified with HCl. Total lipids were extracted overnight two times with 20 volumes of chloroform/methanol (2:1 v/v). Aliquots of mucosal extracts
(4 ml) were evaporated to dryness and counted for radioactivity. The
cecum was clamped and opened by incision, and its content was collected
after rinsing with 2-ml ice-cold normal saline. Lipids were extracted
as mentioned above, and their radioactivity was determined by the
liquid scintillation method. To evaluate the gastric emptying, the
stomach of the rats was clamped at the cardia and pylorus sphincter and
removed. Its content was collected on ice after rinsing with 2 ml of
ice-cold normal saline and homogenized with a Potter. Aliquots (500 µl) were used for scintillation counting.
In a second set of experiments, the test meal was directly infused in
the duodenum to avoid a potential proteolysis of the C-terminal domain
in the stomach. The rats were anesthetized with ketamine-xylazine,
their stomach was ligaturated, and a catheter was inserted in their
duodenum. The test meal (1.5 ml) was infused into the duodenum for 30 min using a peristaltic pump. For the test group (n = 14) 0.1 mg of porcine C-terminal domain in 0.5 ml of water was mixed
with the meal, whereas only 0.5 ml of water was added to the meal of
the control group (n = 17). The rats were kept
anesthetized during the experiment. They were killed after 2 h of
digestion, and their intestinal content was analyzed as above mentioned.
Radioactivity Measurements--
14C radioactivity
was measured by dual scintillation counting in the presence of 15 ml of
either Pico-Fluor 40 or Insta-Fluor liquid scintillation (Packard,
France) in a scintillation spectrometer (Packard 1600 TR) with an
external standard for quench correction. Results were expressed in
disintegration per min (dpm).
Statistical Analysis--
The statistical significance of the
results was analyzed by the one-way analysis of variance and the
difference among treatment groups were assessed by Fischer's test
(14). Differences associated with a p value < 0.05 were considered statistically significant.
Molecular Properties of the Porcine C-terminal Domain--
The
C-terminal domain was obtained from limited proteolysis of native
porcine lipase and purified as indicated under "Experimental Procedures." SDS-PAGE analysis, amino acid composition (data not shown), N-terminal sequencing (Ala-Arg-Trp-Arg-Tyr-Lys-Val-Ser) indicated that the purified domain corresponds to the expected intact
domain (Ala337-Cys445, using the porcine
lipase numbering system, Ref. 5). Based on the molecular mass (12,850 Da) determined by mass spectrometry experiments, the sequence
400FIWYNNNVI408 has been corrected to
400FIWYNNVI407.
The ability of the purified domain to properly bind colipase was
checked by spectrofluorometry as previously reported (9). In solution,
the isolated domain was shown to display an affinity for colipase
similar to that of lipase (Kd ~10 Lipase Inhibition by the C-terminal Domain--
The influence of
the C-terminal domain on the rate of hydrolysis of emulsified
tributyrin by native lipase was investigated using either submicellar
or supramicellar NaTDC concentrations. In all the experiments, an
equimolar ratio of lipase relative to colipase was used.
As shown in Fig. 1, in the presence of
NaTDC micelles, addition of the C-terminal domain leads to a noticeable
inhibition of lipase activity. The inhibition efficiency, low around
the NaTDC critical micellar concentration (CMC ~1 mM),
increases with the NaTDC concentration up to 4 mM. Beyond
this concentration, no more significant variation is observed. For each
NaTDC concentration, increasing the C-terminal domain concentration
results in an hyperbolic inhibition plot from which a plateau value and
an apparent inhibition constant (Ki app)
corresponding to 50% of the plateau value can be determined. Analysis
of the inhibition parameters reported in Table
II reveals that the affinity between the
C-terminal domain and colipase is increased in the presence of micelles
by at least one order of magnitude as compared with the affinity
between both partners in the absence of micelles. As well, the plateau
value varies with the micelle concentration to reach 70-75%
inhibition of the lipase activity at 4 mM NaTDC.
Lipase inhibition by the C-terminal domain can be reversed by addition
of a large molar excess of colipase relative to lipase. This finding is
consistent with a competition between lipase and the C-terminal domain
for colipase.
Below the CMC, no significant inhibition of the lipase activity
is observed unless a large amount of C-terminal domain is added. For
instance, at 0.5 mM NaTDC, only 9% inhibition is observed for a C-terminal domain concentration of 2 × 10
The influence of the nature of the substrate (short or long chain
triglycerides) on the inhibitory efficiency of the C-terminal domain
was investigated using triolein as substrate. As reported for
tributyrin, the presence of micelles is required to observe a
significant lipase inhibition. The plateau and
Ki app values obtained for 4 mM
NaTDC are close to those determined with emulsified tributyrin (Table
III).
To approach the physiological conditions of intestinal lipolysis, we
tested the inhibitory behavior of the C-terminal domain in the presence
of different mixed micelles, using 10 mM emulsified triolein as substrate. The concentration of total bile salts (6 mM), phospholipids (0.5 mM), and/or oleic acid
(5 mM) approximated concentrations found in duodenum during digestion.
Hyperbolic inhibition plots were still obtained from which the
Ki app and plateau values were determined.
Analysis of these parameters reveals that the composition of the
micelles has no significant influence on the inhibitory efficiency of
the C-terminal domain. This finding is to be correlated to a recent work showing that the size rather than the chemical nature is a
critical parameter for the micelle to be accommodated in the cavity of
the lipase-colipase-micelle ternary complex (15). Using 0.11 M emulsified tributyrin and mixed micelles made of either 6 mM total bile salts or 6 mM total bile salts
and 0.5 mM lecithin, plateau values of inhibition ranging
from 75 to 90% were observed. The Ki app is
quite unaffected by the composition of the micelles (~2 × 10 Evidence of the Formation of a C-terminal Domain-Colipase-Micelle
Ternary Complex--
To demonstrate the formation of such a complex,
we have performed gel filtration experiments on the C-terminal domain
either alone or mixed with colipase in the absence or in the presence of NaTDC micelles. A 1.5 molar excess of C-terminal domain relative to
colipase was used in the C-terminal domain/colipase mixtures to compare
the chromatographic behavior of complexed and uncomplexed C-terminal
domain. As shown in Fig. 2, molecular
sieving of colipase/C-terminal domain mixtures, with or without NaTDC
micelles, yields two peaks. In each case, using SDS-PAGE analysis, the
first eluted peak was shown to contain both proteins, indicating the
formation of a colipase-C-terminal domain complex, the molar excess of
C-terminal domain being eluted under the second peak. However, the
elution volume of the colipase-C-terminal domain complex in the
presence of micelles is lower than that observed in the absence of
micelles. This finding is consistent with an increase in molecular size of the complex likely caused by the binding to NaTDC micelles. By
contrast, the elution volume of the C-terminal domain is not significantly affected by the presence of micelles, indicating that
this domain does not interact with a micelle. The same experiments were
performed with colipase and lipase. To normalize all the data, the
Kav values were determined (Table
IV).
Analysis of these values clearly shows that the C-terminal
domain-colipase complex has a Kav value
significantly lower in the presence of micelles than in the absence of
micelles. Moreover, as expected from the respective molecular size of
the two complexes, the lipase-colipase-micelle complex has a still
lower Kav value than that of the
colipase-C-terminal domain complex in the presence of micelles. These
findings, together with the well known observation that colipase, in
contrast to the C-terminal domain, can bind a micelle, are consistent
with the formation of a ternary complex associating the C-terminal
domain, colipase, and a micelle.
In Vivo Inhibition of Lipolysis by the C-terminal
Domain--
Preliminary in vivo experiments were performed
on rats as described under "Experimental Procedures." The porcine
C-terminal domain was either given by mouth or infused in the duodenum
after ligature of the stomach.
In vitro assays showed that the porcine C-terminal domain is
stable for hours at pH values ranging from 2.0 to 9.5 and presents a
moderate sensitivity to pepsin (data not shown). Therefore, in a first
set of experiments, the C-terminal domain was mixed to the test meal
and orally given to the rats. After 3.5 h of digestion, the rats
were killed. A 90% gastric emptying was observed after 3.5 h of
digestion for both the control rats and the rats treated with 1 mg of
C-terminal domain, indicating that the presence of the C-terminal
domain has no effect on the gastric emptying.
As shown in Fig. 3A, the total
14C radioactivity (associated with mono, di, and triolein)
found in the intestine of the rats treated with the C-terminal domain
is significantly higher than that found in the intestine of the rats of
the control group. This finding is indicative of a lower extent of
triolein hydrolysis in the presence of the C-terminal domain. No
radioactivity was found in the cecum, as expected.
In the second set of experiments, the C-terminal domain was infused in
the duodenum. After 2 h of digestion, the total 14C
radioactivity recovered in the intestine of the rats treated with the
C-terminal domain was again higher than that of the control group (Fig.
3B). It must be stressed that in this case the same extent
of inhibition of lipolysis is obtained with a 10-fold lower dose of
C-terminal domain (0.1 mg instead of 1 mg per rat). These results
clearly demonstrate that the C-terminal domain behaves as a lipase
inhibitor in vivo.
These results clearly demonstrate that in vitro under
conditions approximating the physiological conditions, the isolated C-terminal domain of lipase behaves as a potent inhibitor of the enzyme, provided either simple or mixed micelles are present. The
C-terminal domain acts as a direct competitor of lipase by binding
colipase thus diverting it from its lipase-anchoring function. The
presence of micelles triggers the inhibitory efficiency of the
C-terminal domain by increasing the affinity between both partners
through supplementary interactions. This is consistent with the role of
the micelle in the ternary complex described by Hermoso et
al. (7). The direct binding of a micelle to the C-terminal
domain-colipase complex has been shown by molecular sieving
experiments. Based on the decrease of the Kav
value of the C-terminal domain-colipase complex in the presence of
micelles and on the well established finding that colipase possesses a specific lipase binding site distinct from its micelle binding site, it
can be proposed that a ternary complex associating the C-terminal
domain, colipase, and a single micelle is formed in solution. The size
of the micelle rather than its chemical nature is determinant for the
formation of such a complex as previously observed for the
lipase-colipase-micelle ternary complex. The finding that the
inhibitory effect of the C-terminal domain does not depend upon the
nature of the substrate is in agreement with previous experimental data
showing that the lipase C-terminal domain/colipase binding does not
directly involve the lipid/water interface and further supports the
assumption that the ternary complex (C-terminal
domain-colipase-micelle) is formed in solution.
Therefore, we propose that this inhibitory effect is likely to proceed
through the formation of an inactive C-terminal domain-colipase-micelle complex in which by analogy with the active lipase ternary complex the
micelle is located in the cavity delineated by the C-terminal domain
and colipase (Fig. 4).
INTRODUCTION
TOP
ABSTRACT
INTRODUCTION
EXPERIMENTAL PROCEDURES
RESULTS
DISCUSSION
REFERENCES
EXPERIMENTAL PROCEDURES
TOP
ABSTRACT
INTRODUCTION
EXPERIMENTAL PROCEDURES
RESULTS
DISCUSSION
REFERENCES
-phosphatidylcholine and tributyrin were purchased
from Sigma.
) of 6.65 × 104
M
1 cm
1, 0.4 × 104 M
1 cm
1 and
1.2 × 104 M
1
cm
1 for lipase, colipase, and C-terminal domain, respectively.
Vo)/(Vt
Vo) where Ve, Vo, and Vt correspond to
the elution volume, the void volume, and the total volume of the
column, respectively.
9 M and
the lipase/colipase ratio varied from 0.9 to 1.2. One unit corresponds
to the release of 1.0 µmol of fatty acid/min. The lipase activity was
measured either in the absence or in the presence of increasing amounts
of a stock solution of porcine lipase C-terminal domain
(10
4 M). Pure or mixed bile salts were added
to the assay from either a 15 mM stock solution of NaTDC or
a 180 mM stock solution of a physiological mixture of bile
salts (total bile salts) containing 54, 46, 22, 20, 23, and 12 mM of glycocholic acid, glycochenodeoxycholic acid,
glycodeoxycholic acid, taurocholic acid, taurochenodeoxycholic acid,
and taurodeoxycholic acid, respectively (13).
Composition of the liquid test meals
RESULTS
TOP
ABSTRACT
INTRODUCTION
EXPERIMENTAL PROCEDURES
RESULTS
DISCUSSION
REFERENCES
6
M).
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Fig. 1.
Inhibition of the lipase activity on
emulsified tributyrin by the isolated C-terminal domain at different
NaTDC concentrations. Lipase activity was potentiometrically
determined at 25 °C using 0.11 M emulsified tributyrin,
pH 7.5 in the presence of colipase. The lipase and colipase
concentrations were in the range of 10 9 M.
The lipase activity was measured in the presence of increasing amounts
of a stock solution of porcine lipase C-terminal domain
(10
4 M) at different NaTDC concentrations:
, 1 mM;
, 2 mM;
, 4 mM;
, 6 mM; and
, 8 mM NaTDC.
Influence of the NaTDC concentration on the kinetic parameters of
lipase inhibition by the isolated C-terminal domain
5 M as compared with 70-75% inhibition at
4 mM NaTDC. The addition order of the C-terminal domain in
the kinetic assays (before or after lipase) does not noticeably affect
its inhibitory effect.
Effect of simple and mixed micelles on the kinetic parameters of lipase
inhibition by the isolated C-terminal domain
9 M. The lipase activity was measured
in the presence of simple or mixed micelles. The composition of the
total bile salt mixture is described in "Experimental Procedures."
7 M).
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Fig. 2.
C-terminal domain-colipase interactions
during gel filtration on Ultrogel AcA 54 in the absence or in the
presence of NaTDC micelles. The column (90 cm × 1 cm) was
equilibrated and eluted with a 20 mM Tris-HCl buffer, pH
7.6, containing 0.1 M NaCl, 1 mM benzamidine,
and either no NaTDC or 4 mM NaTDC. Flow rate, 6 ml/h;
fraction volume, 0.8 ml. A, elution profile of the
C-terminal domain alone in the absence of NaTDC. B and
C, elution profile of a mixture of colipase and C-terminal
domain (1.5 molar excess of C-terminal domain) in the absence
(B) or in the presence (C) of 4 mM
NaTDC. Insets, 15% SDS-PAGE: lane 1, colipase;
lane 2, C-terminal domain; lane 3, first peak;
lane 4, second peak.
Kav values for colipase, C-terminal domain and lipase
5 M (volume, 0.8 ml).
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Fig. 3.
Effect of the C-terminal domain on the extent
of intestinal lipolysis, in vivo. The extent of lipolysis is
expressed as the percentage of [14C]lipids (mono, di, and
triolein) recovered in the total intestine relative to the ingested
(A) or infused (B) [14C]triolein.
A, percent of [14C] lipids recovered after
3.5 h of digestion in rats fed with test meals containing the
C-terminal domain (1 mg per rat) and in control rats. The percent is
calculated relative to the amount of 14C radioactivity
resulting from the gastric emptying (90% of total ingested
[14C]triolein). The bar is the mean ± S.E. of 10 individual values for either the control group or the
C-terminal-treated group. The differences between the groups are
significant (p < 0.05). B, percent of
[14C]lipids recovered after 2 h of digestion in
control rats and in rats for which the C-terminal domain was infused
(0.1 mg per rat) into the duodenum after ligature of the stomach. The
bar is the mean ± S.E. of 17 (control group) or 14 (C-terminal-treated group) individual values. The differences between
the groups are significant (p < 0.05).
DISCUSSION
TOP
ABSTRACT
INTRODUCTION
EXPERIMENTAL PROCEDURES
RESULTS
DISCUSSION
REFERENCES
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Fig. 4.
Schematic representation of the mechanism of
lipase inhibition by the C-terminal domain. Lipase, colipase, and
C-terminal domain models are based on the C tracing of
lipase-colipase complexes (4, 5, 7). The figure was prepared
using WebLab® Viewer ProTM. The presence of the C-terminal domain
decreases the amount of colipase available for lipase and thus reduces
the amount of the active lipase ternary complex.
In such a model, the domain behaves as a "protein lure" toward colipase, lowering the amount of active lipase/colipase/micelle ternary complex and thus reducing intestinal fat absorption. Preliminary trials performed on rats appear promising for the use of the C-terminal domain as an inhibitor of lipolysis in vivo. A similar decrease of lipolysis was observed when the animals were treated by this domain either orally or by infusion in the duodenum after ligature of the stomach, thus implying that the C-terminal domain behaves as an effective inhibitor of lipolysis in the intestine rather than in the upper part of the digestive tract. This finding emphasizes the specificity of the domain toward the pancreatic lipase/colipase system. These results are also consistent with a noticeable resistance of the domain to proteolysis by pancreatic proteases in the intestine, as previously observed in vitro (16). Moreover, the inhibitory effect of the porcine C-terminal domain in the rat confirms previous findings showing that the lipase/colipase binding is well conserved among species (17, 18).
Therefore, these in vivo results corroborate the mode of inhibition postulated in vitro, namely the C-terminal domain behaves as a specific noncovalent inhibitor of pancreatic lipase by acting as a "protein lure" toward colipase, in contrast to active site-directed inhibitors, which can act on a large number of secretory and intracellular mammalian lipases (19, 20).
In conclusion, this work describes a new specific mild way to control
the activity of the pancreatic lipase/colipase system and further
emphasizes the importance of the bile micelles in lipase/colipase
binding. Based on the positive preliminary in vivo results,
this work might also offer promising perspectives in the health field
because reducing the level of fat absorption by controlling the dietary
triglyceride digestion by gastrointestinal lipases is one of the
concerns of industrialized countries in the campaign against obesity
and some hyperlipidemia (21).
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ACKNOWLEDGEMENTS |
---|
We thank Jacques Bonicel and Angela Guevara for performing the mass spectrometry and sequence analyses. We also acknowledge Michelle Bonneil and Melitza Maffi for their skillful assistance in the in vivo experiments. We acknowledge Gérard Pieroni for helpful discussions.
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FOOTNOTES |
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* This research was supported in part by Grant 930303 from the Institut National de la Santé et de la Recherche Médicale and grants from the Conseil Général des Bouches du Rhône and from the Fondation pour la Recherche Médicale.The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
Recipient of financial support from the Laboratoire LAPHAL.
¶ To whom correspondence should be addressed. Tel.: 33 04 91 75 86 19; Fax: 33 04 91 75 15 62; E-mail: chapus@marseille.inserm.fr.
Published, JBC Papers in Press, January 11, 2001, DOI 10.1074/jbc.M010328200
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ABBREVIATIONS |
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The abbreviations used are: NaTDC, sodium taurodeoxycholate; CMC, critical micelle concentration; PAGE, polyacrylamide gel electrophoresis.
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REFERENCES |
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