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PubMed2004

Micellar electrokinetic chromatography for determination of drug partition in phospholipids.

The lipophilicity of pipemidic, nalidixic and oxolinic acids was determined by forming phospholipidic micelles directly in an electrophoretic capillary. Phosphatidylcholine derivatives, namely L-alpha-dilauroyl phosphatidylcholine (DLPC) or L-alpha-dimiristoyl phosphatidylcholine (DMPC), were added in the run buffer (50 mM phosphate buffer at pH 7.4). To obtain a mixed micelle, phospholipidic derivatives and sodium cholate were together added in the run buffer. Considering the increasing of migration time when phosphatidylcholine derivative is added in the run buffer, Ks can be determined and then quinolones lipophilicity.

Anti-Infective Agents↗

PubMed2005

Absorption enhancement, mechanistic and toxicity studies of medium chain fatty acids, cyclodextrins and bile salts as peroral absorption enhancers.

The objective of the present investigation was to evaluate an oral 'drug delivery' approach, which involves co-administration of absorption enhancers (AEs). The representative low permeable hydrophilic (biopharmaceutic classification system (BCS) Class III) drugs used in the study comprised of cefotaxime sodium and ceftazidime pentahydrate, whereas low permeable lipophilic (BCS Class IV) drugs include cyclosporin A and lovastatin. AEs from three different chemical classes, namely, medium chain fatty acids (sodium caprylate and caprate), cyclodextrins (beta-cyclodextrin, hydroxypropyl beta-cyclodextrin) and bile salts (sodium cholate and deoxycholate) were evaluated for absorption enhancement efficacy, mechanism of action and toxicity using in vitro everted intestinal sac model. These AEs were found to enhance intestinal permeability of drugs from 2- to 27-fold. Light microscopy studies of intestinal sac incubated with AEs for 120 min revealed morphological changes in absorptive mucosa and rank order of toxicity were cyclodextrins>bile salts congruent with medium chain fatty acids. Fluorescence polarization studies indicated that brush bordered membrane vesicles labeled with lipophilic (DPH, 12AS) and hydrophilic dyes (ANS), when treated with AEs exhibited concentration and time dependent decrease in fluorescence polarization. Total protein released in presence of AEs was more than control but considerably less than EDTA (0.58% w/v), which is known to cause toxic release of proteins from cell. Overall, AEs were found to significantly enhance drug permeability by decreasing lipid membrane fluidity and/or interacting with hydrophilic domains of membrane, and has the potential to improve oral delivery.

Animals↗

PubMed2004

Effect of the adaptation to high bile salts concentrations on glycosidic activity, survival at low PH and cross-resistance to bile salts in Bifidobacterium.

Six derivatives with increased resistance to ox gall (MIC: > or = 1% w/v) and one derivative resistant to sodium cholate (MIC: 0.8% w/v) were obtained from more sensitive original Bifidobacterium strains. These microorganisms, and two additional cholate resistant derivatives obtained in a previous study (Int. J. Food Microbiol. 82 (2003) 191), were partially characterised in this study. Acquisition of resistance against a given bile salt, also conferred cross-resistance to other bile salts, and promoted an increase in the survival of these microorganisms at low pH. Bile resistance levels of derivatives were dependent on the external pH so that the resistance was lower at neutral pH values than in acidic environments. In addition, the acquisition of bile resistance induced changes on glycoside-hydrolysing activities of derivatives obtained from five out of eight original strains, with certain activities such as beta-glucosidase showing more than tenfold increases in some of these microorganisms. These data suggest that the exposure to high bile salts concentrations may have induced a synergic response on Bifidobacterium for the adaptation to the conditions of the gastrointestinal tract. This could have improved the survival at low pH in these microorganisms, the resistance to high bile salts concentrations, and the assimilation of non-digestible carbohydrates by the enhancement of some glycoside-hydrolysing activities.

Adaptation, Physiological↗

PubMed2006

Photodynamic ultradeformable liposomes: Design and characterization.

Hydrophobic ([tetrakis(2,4-dimetil-3-pentyloxi)-phthalocyaninate]zinc(II)) (ZnPc) and hydrophilic ([tetrakis(N,N,N-trimethylammoniumetoxi)-phthalocyaninate]zinc(II) tetraiodide) (ZnPcMet) phthalocyanines were synthesized and loaded in ultradeformable liposomes (UDL) of soybean phosphatidylcholine and sodium cholate (6:1, w/w, ratio), resulting 100 nm mean size vesicles of negative Zeta potential, with encapsulation efficiencies of 85 and 53%, enthalpy of phase transition of 5.33 and 158 J/mmol for ZnPc and ZnPcMet, respectively, indicating their deep and moderate partition into UD matrices. Matrix elasticity of UDL-phthalocyanines resulted 28-fold greater than that of non-UDL, leaking only 25% of its inner aqueous content after passage through a nanoporous barrier versus 100% leakage for non-UDL. UDL-ZnPc made ZnPc soluble in aqueous buffer while kept the monomeric state, rendering singlet oxygen quantum yield (Phi(Delta)) similar to that obtained in ethanol (0.61), whereas UDL-ZnPcMet had a four-fold higher Phi(Delta) than that of free ZnPcMet (0.21). Free phthalocyanines were non-toxic at 1 and 10 microM, both in dark or upon irradiation at 15 J/cm2 on Vero and J-774 cells (MTT assay). Only liposomal ZnPc at 10 microM was toxic for J-774 cells under both conditions. Additionally, endo-lysosomal confinement of the HPTS dye was kept after irradiation at 15 J/cm2 in the presence of UDL-phtalocyanines. This could lead to improve effects of singlet oxygen against intra-vesicular pathogen targets inside the endo-lysosomal system.

Animals↗

PubMed2005

Physicochemical investigations of microemulsification of eucalyptus oil and water using mixed surfactants (AOT+Brij-35) and butanol.

Microemulsification of a vegetable oil (eucalyptus) with single and mixed surfactants (AOT and Brij-35), cosurfactant of different lipophilicities (isomers of butanol), and water were studied at different surfactant and cosurfactant mixing ratios. The phase diagrams of the quaternary systems were constructed using unfolded and folded tetrahedron, wherein the phase characteristics of different ternary systems can be underlined. The microemulsion zone was found to be dependent upon the mixing ratios of surfactant and cosurfactant; the largest microemulsion zone was formed with 1:1 (w/w) S:CS. The effects of temperature and additives (NaCl, urea, glucose, and bile salts of different concentrations) on the phase behavior were examined. The mixed microemulsion system showed temperature insensitivity, whereas the Brij-35 (single) stabilized system exhibited a smaller microemulsion zone at elevated temperature. NaCl and glucose increased the microemulsion zone up to a certain concentration, beyond which the microemulsion zones were decreased. These additives decreased the microemulsion zones as temperature was increased. The effect of urea on microemulsion zone was found to be insignificant even at the concentration 3.0 mol dm(-3). Little effect on microemulsion zone was shown by NaC (sodium cholate) at 0.25 and 0.5 mol dm(-3) at different temperatures. The conductance of the single (AOT) and mixed microemulsion system (AOT+Brij-35) depends upon the water content and mixing ratios of the surfactants, and a steep rise in conductance was observed at equal weight percentages of oil and water. Viscosities for both single (AOT) and mixed (AOT+Brij-35) surfactant systems passed through maxima at equal oil and water regions showing structural transition. The viscosities for microemulsion systems increased with increasing Brij-35 content in the AOT+Brij-35 blend. Conductances and viscosities of different monophasic compositions in the absence and presence of additives (NaCl and NaC) were measured at different temperatures. The activation energy of conduction (DeltaE(cond)( *)) and the activation enthalpy for viscous flow (DeltaH(vis)( *)) were evaluated. It was found that both DeltaE(cond)( *) and DeltaH(vis)( *) were a function of the nature of the dispersion medium. Considering the phase separation point of maximum solubility, the free energy of dissolution of water or oil (DeltaG(s)(0)) at the microdispersed state in amphiphile medium was estimated and found to be a function of surfactant composition.

Journal Article↗

PubMed2005

A fluorimetric and circular dichroism study of hemoglobin--effect of pH and anionic amphiphiles.

In this work, bovine hemoglobin (Hb) has been studied mainly by the fluorescence method. pH has been found to exert a profound effect on Hb structure. This has been confirmed by fluorescence and circular dichroism (CD) studies. The pH-induced change in quaternary structure of Hb indirectly affects its secondary structure. This in turn affects ligand binding to Hb at various pH. The binding of two amphiphiles, a bile salt and a surfactant, have been investigated. The pH-induced structural modification of Hb has been confirmed by studies with the well-known denaturant urea and the polarity probe ANS, which has been used as an extrinsic fluorophore.

Animals↗

PubMed2006

Inducing effect of liposomalization on the transdermal delivery of hydrocortisone: creation of a drug supersaturated state.

In order to investigate the effect of liposomal drugs on skin delivery, it was postulated that the process of liposomalization might lead the drug to an overpredicted solubility state which has far-reaching implications for drug skin permeation and accumulation. In this regard, conventional (CL) and flexible liposomes (FL) were prepared by the lipid film hydration method and the particles were downsized by sonication using hydrocortisone (HC) as a poorly water soluble model drug. The solutions derived from the whole CL and FL suspensions eluted on a Sephadex G-50 column (SG-50) demonstrated that most part of HC not only resides solely in the water phase but also it might exist in an improved solubility state. The results of the in vitro study using rat abdominal skin and occlusive application indicated that HC penetrated and accumulated much better solely than when associated with CL or FL. In regard to the penetration of the non-entrapped HC associated to liposomes bilayer fragments, a very small amount of phospholipids in the non-liposomal part eluted on SG-50 was found that could not justify by itself the penetration of HC associated to liposome bilayer fragments. It was proposed that all the steps of the liposomes preparation process might contribute for the increased HC solubility state, but definitively the presence of phospholipids played a crucial role on improving the HC solubility in the absence of sodium cholate. In comparison with commercially available ointments, the non-entrapped HC solution derived from the whole CL suspension eluted on SG-50 showed a higher concentration of HC accumulated and more uniformly distributed as well in the epidermis and dermis compartments. In addition, the thermodynamic activity of the non-entrapped HC solutions maintaining a driving force of the drug across the skin barrier pointed out that the level of HC solubility achieved during liposome preparation has far-reaching implication for drug skin permeation and accumulation in the experimental conditions used. The findings also indicated that the non-entrapped drug solutions obtained on the process of liposomalization could be useful on transdermal drug delivery systems, particularly for improving the permeation and accumulation capacity of poorly soluble drugs.

Administration, Cutaneous↗

PubMed2004

Development and validation of a HPLC method for routine quantification of the decapeptide Cetrorelix in liposome dispersions.

The development and validation of an HPLC method for the quantification of the decapeptide Cetrorelix (acetyl-D-2-naphthylalanyl-D-4-chlorphenylalanyl-D-3-pyridylalanyl-seryl-tyrosyl-D-citrullyl-leucyl-arginyl-prolyl-d-alaninamide), a potent antagonist of the luteinising hormone-releasing hormone in liposome dispersions is described. An isocratic reversed phase method with UV-detection appeared most appropriate. Several detergents were tried to disrupt liposomes. Furthermore, detergents turned out to be useful, because they minimised unwanted loss of Cetrorelix due to adsorption to the vial surfaces. Triton X-100 was found most effective, while sodium cholate led to quantification problems. In the presence of 2.5% Triton X-100 calibration curves with a high degree of linearity were achieved in the desired range of 0.2-10 microg/ml. The limits of detection and quantification of Cetrorelix were calculated from the peak-to-noise ratio to be 11 and 37 ng/ml, respectively. The repeatability of the method in presence of phospholipid and Triton was good with relative standard deviations (R.S.D.) ranging from 0.8% (at 0.05 microg/ml) to 1.5% (at 0.2 microg/ml). The presence of liposomes at phospholipid contents of up to 0.25mg/ml did not significantly affect the slope or linearity of the calibration curve, nor the peak-to-noise ratio.

Chromatography, High Pressure Liquid↗

PubMed2005

Application of non-aqueous micellar electrokinetic chromatography to the analysis of active components in radix Salviae miltiorrhizae and its medicinal preparations.

A simple, economical and effective non-aqueous micellar electrokinetic chromatography (NAMEKC) method was developed for simultaneous assay of three bioactive components (cryptotanshinone, tanshinone IIA and tanshinone I) in radix Salviae miltiorrhizae and its medicinal preparations for the first time. After optimization of separation conditions, a buffer of 140 mmol l(-1) sodium cholate (SC) in methanol was selected for the separation of the three tanshinones, but baseline separation of tanshinone I and tanshinone IIA in practical samples was not achieved. Therefore, second-order derivative electropherograms were applied for resolving overlapping peaks. Regression equations revealed good linear relationships (correlation coefficients 0.995-0.999) between peak heights in second-order derivative electropherograms and concentrations of the three analytes. The recoveries of three constituents ranged from 91.3 to 105.7%. The results indicated that baseline separation of the analytes was hard to be achieved in practical samples sometimes and second-order derivative electropherograms was applicable for the resolving and analysis of overlapping peaks.

Chemical Phenomena↗

PubMed2005

Separation and simultaneous determination of rutin, puerarin, daidzein, esculin and esculetin in medicinal preparations by non-aqueous capillary.

A simple method for the simultaneous determination of five bioactive components (rutin, puerarin, daidzein esculin and esculetin) in traditional medicinal preparations by non-aqueous capillary electrophoresis with UV detection has been developed for the first time. A running buffer composed of 15% acetonitrile, 2.5% acetic acid and 90 mM sodium cholate in methanol was found to be the most suitable for this separation. The limits of detection for five analytes were over the range of 0.050-1.216 microg ml(-1). The relative standard deviations (R.S.Ds.) of the migration times and the peak areas of the analytes were in the range of 1.3-2.9% and 2.2-2.7% (intraday), 1.7-1.9% and 2.8-3.6% (interday), respectively. In the tested concentration range, linear relationships (correlation coefficients: 0.9974 for rutin, 0.9976 for puerarin, 0.9981 for daidzein, 0.9972 for esculin and 0.9929 for esculetin) between peak areas and concentrations of the analytes were obtained. This method has been successfully applied to simultaneous determination of the five bioactive components with recoveries over the range of 89.4-107.4%.

Electrophoresis, Capillary↗

PubMed2004

The effect of taurine on cholesterol degradation in mice fed a high-cholesterol diet.

The hypocholesterolemic effect of taurine was examined in mice fed a high-cholesterol diet containing 1% cholesterol and 0.25% sodium cholate. Male C57BL/6 mice were divided into 3 groups: control group (HC), 1% taurine-supplemented group (HCT+), and taurine-deficient group (HCT-) produced by supplying 0.5% guanidinoethyl sulfonate (GES) solution ad libitum instead of water. After they were fed with the respective diet or drinking water for 4 weeks, the liver taurine level was reduced 80% in the HCT- group compared with that in the HC group, although there was no difference in the serum taurine amount between the two groups. The formation ratio of cholesterol gallstones increased from 71% to 100% by taurine deficiency, and decreased to 0% by taurine supplementation. Compared with the HC group, serum and liver cholesterol significantly decreased, and the excretion of fecal bile acid notably rose in the HCT+ group but tended to lower in the HCT- group. There were no differences in LDL receptor protein level among the three groups. In the subsequent experiment, triglycerides (TG) secretion rate was determined and found to be significantly suppressed by taurine supplementation. In conclusion, it is suggested that taurine does not up-regulate LDL receptor protein level, and the decrease in cholesterol in the circulation is mainly due to its suppressive effect on TG secretion from the liver.

Analysis of Variance↗

PubMed2006

Roles of nuclear receptors in the up-regulation of hepatic cholesterol 7alpha-hydroxylase by cholestyramine in rats.

Nuclear receptors are involved in regulating the expression of cholesterol 7alpha-hydroxylase (CYP7A1), however, their roles in the up-regulation of CYP7A1 by cholestyramine (CSR) are still unclear. In the present study, male Wistar rats were divided into four groups and fed [high sucrose + 10% lard diet] (H), [H + 3% CSR diet] (H + CSR), [H + 0.5% cholesterol + 0.25% sodium cholate diet] (C), or [C + 3% CSR diet] (C + CSR) for 2 weeks. Cholestyramine decreased serum and liver cholesterol levels significantly in rats fed C-based diets, but had no effect on these parameters in rats fed H-based diets. Cholestyramine raised hepatic levels of CYP7A1 mRNA and activity in both groups. The gene expression of hepatic ATP-binding cassettes A1 and G5, regulated by liver X receptor (LXR), were unchanged and down-regulated by cholestyramine, respectively. The mRNA levels of the hepatic ATP-binding cassette B11 and short heterodimer partner (SHP), regulated by farnesoid X receptor (FXR), were not changed by cholestyramine. C-based diets, which contained cholesterol and cholic acid, increased SHP mRNA levels compared to H-based diets. Consequently, in rats fed the C+CSR diet, hepatic FXR was activated by dietary bile acids, but the hepatic CYP7A1 mRNA level was increased 16-fold compared to that in rats fed an H diet. These results suggest that cholestyramine up-regulates the expression of CYP7A1 independently via LXR- or FXR-mediated pathways in rats.

Animals↗

PubMed2005

Purification and characterization of the creatine transporter expressed at high levels in HEK293 cells.

The bovine creatine transporter (CreaT) has been purified from membranes of HEK293 cells stably expressing high levels of the transporter. Membranes were solubilized with decyl maltoside and the CreaT was purified (90% pure) by affinity chromatography on wheat germ agglutinin (WGA)-Sepharose and gel-filtration. The CreaT was shown to be an approximately 70 kDa glycoprotein by SDS-polyacrylamide gel electrophoresis and Western blotting. Identification of the CreaT was confirmed by sequencing tryptic peptides by mass spectrometry. Laser light scattering showed the majority of the CreaT to be present as a 224 kDa species. Additional purification was obtained when the Creat was eluted from the WGA column and purified by gel-filtration in Fos-choline 12 instead of decyl maltoside, followed by a second WGA affinity step to exchange the detergent for sodium cholate. This resulted in a 30-fold purification (95% purity) of the approximately 70kDa CreaT, with a yield of 15%. From this, it is estimated that the CreaT comprises approximately 3% of total HEK293-CreaT membrane protein. Gel-filtration showed the transporter to migrate with an apparent molecular mass of 210 kDa. Circular dichroism showed a predominantly alpha-helical structure, consistent with the 12 transmembrane domains predicted for the transporter. This work has enabled the purification of the CreaT in amounts ( approximately 100 microg) that make it feasible to consider structural studies of a member of the Na(+)- and Cl(-)-dependent neurotransmitter transporter family.

Animals↗

PubMed1991

The catalytic role of subunit IV of the cytochrome b6-f complex from spinach chloroplast.

The catalytic role of subunit IV, the Mr 17,000 protein, in the chloroplast cytochrome b6-f complex was established through trypsinolysis of the complex under controlled conditions. When purified chloroplast cytochrome b6-f complex, 1 mg/ml, in 50 mM Tris-succinate buffer (pH 7.0) containing 1% sodium cholate and 10% glycerol is treated with 80 micrograms of trypsin at room temperature for various lengths of time, the activity of the cytochrome b6-f complex decreases as the incubation time increases. A maximal inactivation of 80% is reached at 7 min of incubation. The trypsin inactivation is accompanied by the destruction of the proton translocation activity of the complex. No alteration of absorption and EPR spectral properties was observed in the trypsin-inactivated complex. Subunit IV is the only subunit in the cytochrome b6-f complex that is digested by trypsin, and the degree of digestion correlates with the decrease of electron transfer activity. The binding of azido-Q to subunit IV of the complex decreases as the extent of inactivation of the cytochrome b6-f complex by trypsin increases. The residue molecular mass of trypsin cleaved subunit IV is about 14 kDa, suggesting that the cleavage site is at lysine 119 or arginine 125 or 126. When the thylakoid membrane was assayed for cytochrome b6-f complex activity, very little activity was observed; and the activity was not sensitive to trypsinolysis. Upon sonication, activity and sensitivity to trypsinolysis was greatly increased, suggesting that subunit IV protrudes from the lumen side of the membrane.

Affinity Labels↗

PubMed1999

Enzymatic reactions in liposomes using the detergent-induced liposome loading method.

Microcompartmentalization is a crucial step in the origin of life. More than 30 years ago, Oparin et al. proposed models based on biochemical reactions taking place in so-called coacervates. Their intention was to develop systems with which semipermeable microcompartments could be established. In the present work we follow their intuition, but we use well-characterized bilayer structures instead of the poorly characterized coacervates. Liposomes from phospholipids can be used as microreactors but they exhibit only a modest permeability and, therefore, chemical reactions occurring inside these structures are depleted after a relatively short period. Here it is shown that even highly stable liposomes from 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) can be used as semipermeable microreactors when treated with sodium cholate. Using this kind of mixed liposomes, we describe a biochemical reaction occurring inside the liposomes while the same reaction is prevented in the external medium. In addition, we show that this cholate-induced permeability of POPC bilayers can even be used to load macromolecules such as enzymes from the outside.

Cholates↗

PubMed1999

Liposomes fuse with sperm cells and induce activation by delivery of impermeant agents.

Sperm cell activation is a critical step in fertilization. To directly investigate the cell signaling events leading to sperm activation it is necessary to deliver membrane impermeant agents into the cytoplasm. In this study, the use of liposomes as possible agent-loading vectors was examined using (1) the octadecylrhodamine B (R18) and NBD phosphatidylethanolamine (NBD DHPE)/rhodamine phosphatidylethanolamine (rhod DHPE) fusion assays in bulk samples, (2) membrane transfer of fluorescence from liposome membranes labeled with R18 and rhodamine-tagged phosphatidylethanolamine (TRITC DHPE), and (3) lumenal transfer of impermeant calcium ions from liposomes to sperm cells, a process that stimulated sperm cell activation. Intermediate-sized unilamellar liposomes (98.17+/-15.34 nm) were prepared by the detergent-removal technique using sodium cholate as the detergent and a phosphatidylcholine/phosphatidylethanolamine/cholesterol (2:1:1 mole ratio) lipid composition. In the R18 fusion assays, self-quenching increased logarithmically with increasing concentrations of R18 in the liposome membranes; addition of unlabeled sperm to R18-labeled liposomes lead to a rapid release of self-quenching. In the NBD DHPE/rhod DHPE resonance energy transfer (RET) fusion assay, RET was rapidly reduced under similar conditions. In addition, individual sperm became fluorescent when TRITC DHPE-labeled liposomes were incubated with unlabeled sperm cells. Incubation of sperm cells with empty liposomes did not significantly affect sperm cell activation and did not alter cell morphology. However, incubation with Ca (10 mM)-loaded liposomes resulted in a time-dependent increase in sperm cell activation (7.5-fold over controls after 15 min). We conclude that liposomes can be used for direct loading of membrane-impermeant agents into sea squirt sperm cell cytoplasm, and that delivery occurs via fusion and content intermixing.

Animals↗

PubMed1999

Incorporation of bacterial membrane proteins into liposomes: factors influencing protein reconstitution.

Meningococcal and gonococcal outer membrane proteins were reconstituted into liposomes using detergent-mediated dialysis. The detergents octyl glucopyranoside (OGP), sodium cholate and Empigen BB were compared with respect to efficiency of detergent removal and protein incorporation. The rate of OGP removal was greater than for cholate during dialysis. Isopycnic density gradient centrifugation studies showed that liposomes were not formed and hence no protein incorporation occurred during dialysis from an Empigen BB containing reconstitution mixture. Cholate-mediated reconstitution yielded proteoliposomes with only 75% of the protein associated with the vesicles whereas all of the protein was reconstituted into the lipid bilayer during OGP-mediated reconstitution. Essentially complete protein incorporation was achieved with an initial protein-to-lipid ratio of 0.01:1 (w/w) in the reconstitution mixture; however, at higher initial protein-to-lipid ratios (0.02:1) only 75% protein incorporation was achieved. Reconstituted proteoliposomes were observed as large (>300 nm), multilamellar structures using cryo-electron microscopy. Size reduction of these proteoliposomes by extrusion did not result in significant loss of protein or lipid. Extruded proteoliposomes were unilamellar vesicles with mean diameter of about 100 nm.

Bacterial Outer Membrane Proteins↗

PubMed1987

Solubilisation and reconstitution of acylcoenzyme A:estradiol-17 beta acyltransferase.

Acylcoenzyme A:estradiol-17 beta acyltransferase in microsomes of bovine placenta cotyledons was strongly membrane bound. The enzyme was solubilised from microsomes by sodium cholate and was reconstituted into phospholipid vesicles. The apparent Km for estradiol-17 beta was 11 microM which was close to the value of 8 microM previously found with the membrane-bound enzyme. Testosterone was also a substrate for the reconstituted enzyme (apparent Km 62 microM) and was a competitive inhibitor (Ki 74 microM) of the acylation of estradiol-17 beta. Although various long-chained fatty acyl CoAs acted as acyl donors, these proved to have widely differing apparent Km values with palmitoleoyl CoA having the highest affinity (Km 24 microM) and arachidonoyl CoA the lowest affinity (Km 330 microM).

Acyltransferases↗