Interaction of the antifungal ketoconazole and its diphenylphosphine derivatives with lipid bilayers: Insights into their antifungal action

Ketoconazole (Ke) is an important antifungal drug, and two of its diphenylphosphinemethyl derivatives (KeP: Ph2PCH2-Ke and KeOP: Ph2P(O)CH2-Ke) have shown improved antifungal activity, namely against a yeast strain lacking ergosterol, suggesting alternative modes of action for azole compounds. In this context, the interactions of these compounds with a model of the cell membrane were investigated, using POPC (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine) large unilamellar vesicles and taking advantage of the intrinsic fluorescence of Ke, KeP and KeOP. Steady-state fluorescence spectra and anisotropy, including partition and aggregation studies, as well as fluorescence lifetime measurements, were carried out. In addition, the ability of the compounds to increase membrane permeability was assessed through carboxyfluorescein leakage. The membrane/water mole fraction partition coefficients (Kp,x): (3.31 ± 0.36) x105, (8.31 ± 1.60) x105 and (4.66 ± 0.72) x106, for Ke, KeP and KeOP, respectively, show that all three compounds have moderate to high affinity for the lipid bilayer. Moreover, KeP, and particularly KeOP interact more efficiently with POPC bilayers than Ke, which correlates well with their in vitro antifungal activity. Furthermore, although the three compounds disturb the lipid bilayer, KeOP is the quickest and most efficient one. Hence, the higher affinity and ability to permeabilize the membrane of KeOP when compared to that of KeP, despite the higher lipophilicity of the latter, points to an important role of Ph2P(O)CH2- oxygen. Overall, this work suggests that membrane interactions are important for the antifungal activity of these azoles and should be considered in the design of new therapeutic agents.

Unraveling environmental effects in the absorption and fluorescence spectra of p-methoxyphenylpiperazine derivatives

The p-methoxyphenylpiperazine motif can be found in many biologically active molecules, including approved drugs. It is characterized by a relatively weak fluorescence, which can be employed in different types of studies involving molecules with this motif. In this work, a thorough analysis of the absorption, excitation and emission spectra of the diphenyl(aminomethyl)phosphine and tris(aminomethyl)phosphine derivatives of p-methoxyphenylpiperazine, supported by the DFT calculations (ωB97XD/6-311++G(d,p)) with NBO and QTAIM analysis also for different model molecules (e.g. 1-(4-methoxyphenyl)-4-methylpiperazine) enabled determination of the mechanisms underlying beneath the electronic transitions and allowed to rationalize mixed solvent effects observed in electronic spectra of the studied compounds. Electronic transition from the ground state to the first excited state can be regarded as the n,π → π* transition with no solvatochromic effects, however the hydrogen bonds between the HBD solvent molecules and the nitrogen atom bound directly to the aromatic ring (N(4)) are shifting strongly the 1st absorption or excitation band maxima to the higher energies. Fluorescence band, as a result of the electron transition from the equilibrated 1st excited state to the ground state, can be described as the π*→π with positive solvatochromism. N(4) in the excited states adopts a sp2 hybridization and is no longer able to form HBs. On the other hand, increased electron density on the aromatic ring makes the emission processes vulnerable to its direct environment.

Anticandidal Cu(I) complexes with neocuproine and 1-(4-methoxyphenyl)piperazine based diphenylaminomethylphosphine: Is Cu-diimine moiety a pharmacophore?

The studies on metal complexes as potential antifungals are of growing interest because they may be the answer to increasingly effective defense mechanisms. Herein we present two new copper(I) iodide or thiocyanide complexes with 2,9-dimethyl-1,10-phenanthroline (dmp) and diphenylphosphine derivative of 1-(4-methoxyphenyl)piperazine (4MP): [CuI(dmp)4MP] (1-4MP) and [CuNCS(dmp)4MP] (2-4MP) - their synthesis, as well as structural and spectroscopic characteristics. Interestingly, while 4MP and its oxide derivative (4MOP) show a very low or no activity against all tested Candida albicans strains (MIC50 ≥ 200 μM against CAF2-1 - laboratory control strain, DSY1050 - mutant without transporters Cdr1, Cdr2, Mdr1; isogenic for CAF2-1, and fluconazole resistant clinical isolates), for 1-4MP and 2-4MP MIC50 values were 0.4 μM, independently on the complex and strain tested. Determination of the viability of NHDF-Ad (Normal Adult Human Dermal Fibroblasts) cell line treated with 1-4MP and 2-4MP showed that for both complexes there was only a 20% reduction in the concentration range ¼ to 2 × MIC50 and the 70% at 4 × MIC50. Subsequently, the MLCT based luminescence of the complexes in aqueous media allowed to record the confocal micrographs of 1-4MP in the cells. The results show that it is situated most likely in the vacuoles (C. albicans) or lysosomes (NHDF-Ad).

Tris(aminomethyl)phosphines and Their Copper(I) (Pseudo)halide Complexes with Aromatic Diimines-A Critical Retrospection

Metal complexes feature a wide range of available geometries, diversified lability, controllable hydrolytic stability, and easily available rich redox activity. These characteristics, combined with the specific properties of coordinated organic molecules, result in many different mechanisms of biological action, making each of the myriads of the classes of metal coordination compounds unique. This focused review presents combined and systematized results of the studies of a group of copper(I) (pseudo)halide complexes with aromatic diimines and tris(aminomethyl)phosphines of a general formula [CuX(NN)PR₃], where X = I^- or NCS^-, NN = 2,2'-bipyridyl, 1,10-phenanthroline, 2,9-dimethyl-1,10-phenanthroline or 2,2'-biquinoline, and PR₃ = air-stable tris(aminomethyl)phosphines. The structural and electronic properties of the phosphine ligands and luminescent complexes are discussed. The complexes with 2,9-dimethyl-1,10-phenanthroline, apart from being air- and water-stable, exhibit a very high in vitro antimicrobial activity against the Staphylococcus aureus and Candida albicans. Moreover, some of these complexes also show a strong in vitro antitumor activity against human ovarian carcinoma cell lines: MDAH 2774 and SCOV 3, CT26 (mouse colon carcinoma), and A549 (human lung adenocarcinoma) cell lines. The tested complexes are moderately able to induce DNA lesions through free radical processes, however the trends do not reflect observed differences in biological activity.

New ternary Fe(III)-8-hydroxyquinoline-reduced Schiff base complexes as selective anticancer drug candidates

Due to the growing prevalence of cancer diseases, new therapeutic options are urgently needed, and drugs based on metal ions other than platinum are alternatives with exciting possibilities. We report the synthesis, characterization and biological effect of mixed-ligand Fe(III)-aminophenolate complexes derived from salicylaldehyde and L-tryptophan with quinoline derivatives as co-ligands, namely 8-hydroxyquinoline (8HQ), [Fe(L)(8HQ)(H₂O)] (1) and its 5-cloro derivative (Cl8HQ), [Fe(L)(Cl8HQ)(H₂O)] (2). The complex bearing the aminophenolate and lacking the quinoline co-ligand, [Fe(L)(Cl)(H₂O)₂] (3), was prepared for comparison. The analytical and spectroscopic characterization revealed that 1 and 2 are octahedral Fe(III) complexes with the aminophenolate acting as a dianionic tridentate ligand and 8HQ co-ligands as bidentate chelates. Spectroscopic techniques and molecular docking studies were used to evaluate the ability of these complexes to bind bovine serum albumin (BSA) and calf thymus DNA. Complex 2 [Fe(L)(Cl8HQ)(H₂O)] was the one showing higher affinity for both biomolecules. Cell viability was assessed in breast, colorectal and bone human cancer cell lines. 1 and 2 were found to be more active than cisplatin in all cell lines tested. A non-tumoral fibroblast line (L929, mouse non-tumoral fibroblasts) was used to evaluate selectivity. The results evidence that 2 shows much higher selectivity than 1 in all cell lines tested, but particularly in bone cancer cells in which selectivity index (SI) values are 8.0 and 18.8 for 1 and 2, respectively.

New anticandidal Cu(i) complexes with neocuproine and ketoconazole derived diphenyl(aminomethyl)phosphane: luminescence properties for detection in fungal cells

Anticandidal activity and a complex luminescence in water solutions of the new copper(i) complexes with a ketoconazole derived phosphane ligand.

New ruthenium(II) coordination compounds possessing bidentate aminomethylphosphane ligands: synthesis, characterization and preliminary biological study in vitro

Addition of aminomethylphosphane P{CH2N(CH2CH2)2O}3 (), PPh2{CH2N(CH2CH2)2O} () or PPh2{CH2N(CH2CH2)2NCH2CH3} () to a methanolic solution of RuCl3 results in reduction of ruthenium(iii) ions giving finally ttt-[RuCl2()2] (), ttt-[RuCl2()2] () and ttt-[RuCl2()2] (). The synthesized complexes are the first examples of ruthenium(ii) coordination compounds possessing aminomethylphosphanes chelating via phosphorus and nitrogen atoms. They were fully characterized (NMR, ESI-MS, IR, elemental analysis, X-ray crystallography). Preliminary studies of the in vitro cytotoxicity on the A549 cell line (human lung adenocarcinoma) and interactions with human serum proteins (albumin and apotransferrin) showed moderate activity of the complexes. Interestingly, the P,N-chelation leads to formation of strained 4-membered Ru-P-C-N-Ru rings, which in the case of and undergo opening in the presence of CH3CN, which results in rearrangement to ctc-[RuCl2()2(CH3CN)2] () and ctc-[RuCl2()2(CH3CN)2] ().

Copper(i) complexes with phosphine derived from sparfloxacin. Part I - structures, spectroscopic properties and cytotoxicity

In this paper we present new copper(i) iodide or copper(i) thiocyanate complexes with hydroxymethyldiphenylphosphine (PPh2(CH2OH)) or phosphine derivatives of sparfloxacin, a 3(rd) generation fluoroquinolone antibiotic agent (PPh2(CH2-Sf)) and 2,9-dimethyl-1,10-phenanthroline (dmp) or 2,2'-biquinoline (bq) auxiliary ligands. The synthesised complexes were fully characterised by NMR and UV-Vis spectroscopy as well as by mass spectrometry. Selected structures were additionally analysed using X-ray and DFT methods. All complexes proved to be stable in solution in the presence of water and atmospheric oxygen for several days. The cytotoxic activity of the complexes was tested against two cancer cell lines (CT26 - mouse colon carcinoma and A549 - human lung adenocarcinoma). Applying two different incubation times, the studies enabled a preliminary estimation of the dependence of the selectivity and the mechanism of action on the type of diimine and phosphine ligands. The results obtained showed that complexes with PPh2(CH2-Sf) are significantly more active than those with PPh2(CH2OH). On the other hand, the relative impact of diimine on cytotoxicity is less pronounced. However, the dmp complexes are characterised by strong inhibitory properties, while the bq ones are rather not. This confirms the interesting and promising biological properties of the investigated group of copper(i) complexes, which undoubtedly are worthy of further biological studies.

Copper(i) complexes with phosphine derived from sparfloxacin. Part II: a first insight into the cytotoxic action mode

A first insight into the cytotoxic action mode of copper(i) iodide or copper(i) thiocyanate complexes with a phosphine derivative of sparfloxacin (a 3^rdgeneration fluoroquinolone antibiotic agent) and 2,9-dimethyl-1,10-phenanthroline or 2,2′-biquinoline as auxiliary ligands.

Coordination versatility of phosphine derivatives of fluoroquinolones. New CuI and CuII complexes and their interactions with DNA

This paper describes syntheses and interactions with DNA of copper(i) and copper(ii) complexes with phosphine derivatives of fluoroquinolone antibiotics (ciprofloxacin and norfloxacin).

Unexpected formation of [Ru(η5-C5H5)(PH{CH2N(CH2CH2)2O}2)(PPh3)2]BF4 – the first “piano-stool” ruthenium complex bearing a secondary aminomethylphosphane ligand

[Ru(η⁵-C₅H₅)(PH{CH₂N(CH₂CH₂)₂O}₂)(PPh₃)₂]BF₄ – unexpected formation of the first “piano-stool” ruthenium complex bearing a secondary aminomethylphosphane ligand.

Di-μ-iodido-bis[(dimethyl 2,2′-biquinoline-4,4′-dicarboxylate-κ2 N,N′)copper(I)]

In the centrosymmetric dinuclear title complex, [Cu₂I₂(C₂₂H₁₆N₂O₄)₂], the Cu^I atom is coordinated in a distorted tetra­hedral geometry by an N,N′-bidentate dimethyl 2,2′-biquinoline-4,4′-dicarboxyl­ate ligand and two symmetry-related I atoms, which act as bridges to a symmetry-related Cu^I atom. The distance between the Cu^I atoms within the dinuclear unit is 2.6723 (11) Å.

The impact of isomers of hemiaminal-1,2,4-triazole conjugates differently substituted in the phenyl ring and their Cu2+ complexes on the catalytic activity of the antigenomic delta ribozyme

The ability of four stable hemiaminals differently substituted in the phenyl ring and their complexes with Cu(2+) ions to inhibit catalytic cleavage of the antigenomic delta ribozyme was compared. The hemiaminals were novel chiral derivatives of 1,2,4-triazole [i.e. (2,4-dinitrophenyl)(4H-1,2,4-triazol-4-ylamino) methanol (2,4-dnbald), (2-nitrophenyl)(4H-1,2,4-triazol-4-ylamino) methanol (2-nbald), (3-nitrophenyl)(4H-1,2,4-triazol-4-ylamino) methanol (3-nbald) and (4-nitrophenyl)(4H-1,2,4-triazol-4-ylamino) methanol (4-nbald)]. The complexes of nbalds with Cu(2+) were characterized using UV and EPR methods and additionally, the formation of 2,4-dnbald-Cu(2+) complex with CuL(2) stoichiometry was confirmed by mass spectrometry. The data suggest that there are two ways in which nbalds and their Cu(2+) complexes can influence catalytic cleavage of antigenomic delta ribozyme. The coordinated Cu(2+) ions may play the role of new cationic ligands increasing the affinity of the complexes to the ribozyme. Such situation occurs in the case of 2- and 2,4-nbald. Their Cu(2+) complexes decrease ribozyme cleavage rates twice more efficiently than uncomplexed compounds. Moreover, the Cu(2+) complexes displace the catalytic divalent metal ions from their strong binding sites located in the ribozyme J4/2 region as shown by the Pb(2+)-induced cleavage approach. On the other hand, 3- and 4-nbald inhibit catalysis more strongly as compared to 2-nbald and 2,4-dnbald but the ribozyme cleavage rates are changed only slightly upon Cu(2+) complexation. The mechanism of ribozyme inhibition by interfering with the formation of a correct ribozyme tertiary structure seems to operate in this case.

The Cu(II)-fluconazole complex revisited. Part I: Structural characteristics of the system

Protonation equilibria and Cu(II) binding processes by an antifungal agent fluconazole, α-(2,4-difluorophenyl)-α-(1H-1,2,4-triazol-1-yl-methyl)-1H-1,2,4-triazole-1-ethanol, were studied using the UV-Vis, EPR and NMR spectroscopic techniques. The protonation constant of fluconazole was determined from NMR titration and attributed to N4' nitrogen atoms using the DFT methods. The spectroscopic data suggest that at pH as low as 0.4 the first complex is formed, in which one or two Cu(II) ions are bound to one of the nitrogen atoms (N4') from triazole rings. Above pH 1.5 each Cu(II) ion is surrounded by two nitrogen atoms (also N4') from two different ligand molecules, forming primary monomeric complexes and above pH=5, both dimeric or oligomeric species occur, which is well registered by the EPR technique. The mixture of Cu(NO(3))(2) with fluconazole in a 1:1 molar ratio in a water (pH=4.5)/ethanol solution gave crystals of [Cu(2)(H(2)O){(C(6)H(3)-2,4-F(2))(CH(2)N(3)C(2)H(2))(2)C-OH}{(C(6)H(3)-2,4-F(2))(CH(2)N(3)C(2)H(2))(2)C-O}(NO(3))](NO(3))(2)·9(H(2)O). This complex is the first example of a cupric 3D polymeric structure with a fluconazole ligand coordinated via both N2' and N4' atoms from the same triazole rings. At higher pH values, we obtained a binuclear complex [Cu(2)(L)(2)(H(2)O)(2)(NO(3))(2)], in which the copper(II) atoms were bridged by the oxygen atoms of the deprotonated OH group of fluconazole. The hypothetical oxidative properties of this system were also examined, however it failed to generate either reactive oxygen species or DNA scission products.

Biological activity and structure dependent properties of cuprous iodide complexes with phenanthrolines and water soluble tris (aminomethyl) phosphanes

This paper presents the biological activity of copper(I) iodide complexes with 1,10-phenanthroline (phen) or 2,9-dimethyl-1,10-phenanthroline (dmp) and three tris (aminomethyl) phosphanes: P(CH2N(CH2CH2)2NCH3)3 (1), P(CH2N(CH2CH2)2O)3 (2) and P (CH2N(CH3)CH2CH2OH)3 (3). Crystallographic and DFT data indicate a significantly stronger binding ability of 3 in the complexes [CuI (phen) P (CH2N (CH3)CH2CH2OH)3] (3P) and [CuI(dmp)P(CH2N(CH3)CH2CH2OH)3] (3N) in comparison to the 1 or 2 ligands. Most probably, this is caused by the relatively small steric requirements of 3. The complexes with dmp exhibit a very high in vitro activity against the Staphylococcus aureus strain (MIC - minimal inhibitory concentration: 2.5-5 μg/mL) and Candida albicans diploid fungus (MIC: 1.25-2.5 μg/mL). All the tested complexes also show a strong in vitro antitumor activity against human ovarian carcinoma cell lines: MDAH 2774 (IC50: 7-2 μM) and cisplatin-resistant SCOV3 (IC50: 3-2 μM). Interestingly, the complexes with dmp of higher biological activity more weakly interact with bovine serum albumin (BSA) and less efficiently cleave the pBluescriptSK+ plasmid.

Factors modulating the interaction of LDL with an arterial lipoprotein complexing proteoglycan: the effect of HDL

The presence of a lipoprotein complexing proteoglycan (LCP) in extracts of human arterial intima/media that forms specific complexes with low density lipoproteins (LDL) has suggested that it may play a role in the interaction of LDL with the arterial wall and the atherogenic process. The formation of insoluble LDL-LCP complexes by incubation of serum with arterial extracts appears directly related to the concentration of LDL and inversely to the content of high density lipoproteins (HDL), indicating that HDL may inhibit the interaction between LDL and LCP. This inhibition is clearly visible by addition of HDL to LCP containing extracts before their incubation with LDL. This effect is also shown by apoHDL but not by lipoprotein-free plasma. It is suggested that the HDL/LDL ratio of the plasma crossing the endothelial barrier may be an important modulator of the net accumulation of LDL in the intima/media and of its contribution to atherogenesis.

Role of protein kinase C on the acute desensitization of renal cortical adenylate cyclase to parathyroid hormone

The mechanisms of adenylate cyclase desensitization to parathyroid hormone are still unclear. Current evidence suggest that the signal generated after PTH binding to receptors results in activation of adenylate cyclase and stimulation of phospholipase C with subsequent activation of protein kinase C. Recent studies have suggested a role of protein kinase C on the regulation of the PTH-dependent receptor-adenylate cyclase system in cultured cells. Therefore, the present studies were conducted to examine the role of protein kinase C on the desensitization of canine renal cortical adenylate cyclase after an acute exposure in vivo to PTH. A group of normal dogs were treated with a single intravenous injection of 1 microgram/k of syn bPTH (1-34) or Nle bPTH (3-34). Ten minutes later, animals were subjected to bilateral nephrectomy and the kidney cortex processed for preparations of basolateral membranes for determinations of adenylate cyclase activity, as well as membrane and cytosolic fractions for analysis of protein kinase C activity. Animals not treated with PTH were used as controls. PTH administration in vivo resulted in a 46.9 +/- 9.3% decrease in maximal adenylate cyclase activity in vitro in response to syn bPTH (1-34) (P < 0.001). Likewise, PTH binding as measured with 125I-Nle8,18,Tyr34-bPTH (1-34)NH2 showed a 40 +/- 3% decrease. This alterations were associated with a marked translocation of protein kinase C from the cytosol to the membrane. Thus, protein kinase C activity in membrane fractions increased from 160.6 +/- 44.8 pmol Pi/min in controls to 500.4 +/- 123 in PTH treated dogs (P < 0.03).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of acidosis on PTH-dependent renal adenylate cyclase in phosphorus deprivation: role of G proteins

These studies examine the regulation of adenylate cyclase in renal cortical membranes from phosphate-deprived and phosphate-deprived acidotic dogs. Enzyme stimulation by parathyroid hormone (PTH) was decreased in phosphate deprivation [Vmax 1,578 +/- 169 vs. 2,581 +/- 219 pmol adenosine 3',5'-cyclic monophosphate (cAMP).mg protein-1 x 30 min-1 in controls, P less than 0.01]. Metabolic acidosis further decreased PTH-stimulated activity. Membranes from phosphate-deprived dogs showed a decrease in Gs alpha-content by cholera toxin-dependent ADP-ribosylation (174 +/- 18 arbitrary units vs. 266.4 +/- 13.6 in controls, P less than 0.01). Metabolic acidosis further decreased Gs alpha-content, P less than 0.01. Gi content by pertussis-dependent ADP-ribosylation was also lower in phosphate-deprived and phosphate-deprived acidotic animals. Gs function was examined by its property to protect the catalytic unit from inactivation by N-ethylmaleimide when preincubated with GTP gamma S. In controls, protection of inactivation was 80% of the maximal activity, whereas in phosphate deprivation protection was less than 50%. In conclusion, metabolic acidosis enhances adenylate cyclase resistance to PTH in phosphate deprivation. These alterations are associated with a decrease in the content and function of Gs alpha, suggesting a role of Gs in the renal adaptation to phosphate depletion and acidosis.

Altered response of adenylate cyclase to parathyroid hormone during compensatory renal growth

The loss of renal mass is associated with functional adaptations in the remaining nephrons to maintain homeostasis. Although parathyroid hormone (PTH) is important in the adaptations to phosphate, the mechanisms are not completely defined. In the present studies we examined the response of the adenylate cyclase system to PTH in renal cortical membranes of rat kidneys ten days after unilateral nephrectomy. The kidneys obtained at the time of the initial nephrectomy were used as controls. Unilateral nephrectomy resulted in contralateral compensatory renal growth, as demonstrated by a 24 +/- 4.7% (P less than 0.01) increase in weight in the remaining kidney. Glomerular filtration rate (GFR) after unilateral nephrectomy was 62% of the control, while basal fractional phosphate excretion was higher in rats with unilateral nephrectomy (7.7 +/- 2.1% vs. 2.9 +/- 0.8%, P less than 0.05). PTH infusion resulted in a similar increase of fractional phosphate excretion and urinary cAMP in both groups. In the absence of added guanine nucleotides, PTH-dependent adenylate cyclase activity in cortical membranes from kidneys with compensatory growth was decreased as compared to controls (Vmax 807.5 +/- 62.7 pmol cAMP/mg protein/30 min vs. 1,384.8 +/- 116.1, respectively, P less than 0.01). The apparent affinity for PTH stimulation of adenylate cyclase (Kact) was unchanged. Magnesium-dependent adenylate cyclase activity was also decreased in the membranes from kidneys with compensatory growth. However, the kinetics of adenylate cyclase for the substrates ATP-Mg or ATP-Mn were similar.(ABSTRACT TRUNCATED AT 250 WORDS)

Partial structure of the active moiety of a lipoprotein complexing proteoglycan from human aorta

Proteoglycans and glycosaminoglycans of the intima-media extracellular matrix have been stated to play a role in lipoprotein deposition associated with atherogenesis. It is therefore important to characterize the active lipoprotein-complexing moiety of these macromolecular aggregates. We have isolated a soluble proteoglycan aggregate of approximately 5 X 10(6) molecular weight after homogenization of human aortic intima-media in an isosmotic sucrose solution, sequential differential centrifugation, dialysis, exclusion chromatography and preparative electrophoresis. This proteoglycan aggregate, labelled lipoprotein-complexing proteoglycan (LCP), has been previously shown to form specific complexes with low density lipoproteins, either isolated or in sera. Density gradient centrifugation in dissociative conditions of the LCP, cellulose acetate acetate electrophoresis of the subfractions, chondroitinases treatment and high performance liquid chromatography of the unsaturated disaccharides indicated that the glycosaminoglycan moiety was composed of 56% chondroitin-6-SO4, 26% hyaluronate and/or undersulfated chondroitin and 17% chondroitin-4-SO4. In pore-gradient polyacrylamide gel electrophoresis, the hyaluronate monomer appeared to have a molecular weight of 250000 while that of the chondroitin sulfates ranged between 50000 and 70000 after extensive treatment with protease. The fractions enriched in the chondroitin sulfate monomers were the most reactive towards LDL and their reactivity was abolished by chondroitinase AC indicating that the lipoprotein-complexing capacity of the LCP aggregate is associated to these molecules.

Characterization and properties of a lipoprotein-complexing proteoglycan from human aorta

The preparation of a proteoglycan (PG) from human aortic intima-media is described. The PG was obtained from intima-media homogenates by differential centrifugation, exclusion chromatography and preparative agarose electrophoresis. Crude or purified preparations of the proteoglycan are capable of forming specific insoluble complexes with LDL, purified or in serum. This product has been labelled lipoprotein-complexing proteoglycan (LCP-3). On agarose and cellulose acetate electrophoresis LCP-3 appears as a single band. However, its glycosaminoglycan (GAG) moiety shows a composition and chromatographic behaviour compatible with hybrid or mixed chains of chondroitin-6-so4, dermatan sulfate and heparin and/or heparan sulfate. The specificity of LCP-3 for LDL disappears when it is treated with testicular hyaluronidase or proteolytic enzymes. Ionic strength, pH, Ca++ and Mg++ modulate the amount of LDL insolubilized. The amino acid composition of the protein from LCP-3 is that of a basic protein(s), perhaps bound covalently through xylose--serine residues to the GAG's. The estimated molecular weight of LCP-3 is 1 to 5 x 10(6) daltons. The presence of LCP-3 to intima-media and its specificity for interacting with LDL at conditions near to physiological ones are suggestive of the role that this type of structure may play in the association of the atherogenic lipoproteins with components of the arterial intima-media.