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PubMed1997

Characterization of Ferritin Adsorption onto Gold

The adsorption of ferritin from phosphate-buffered saline (PBS) onto gold has been examined using a quartz crystal microbalance (QCM), surface plasmon resonance (SPR), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). Application of these techniques allows elucidation of the surface coverage and layer thickness of ferritin on gold. The kinetics of ferritin adsorption onto gold were investigated by monitoring the resonant frequency shift of a QCM. Adsorption isotherms for ferritin in PBS and in air have been measured by QCM. These isotherms suggest less than monolayer coverage of ferritin on gold. A layer thickness of 4.8 ± 0.2 nm was calculated for the dry ferritin film from QCM data. Measurements of the shift in the reflectivity of light at a fixed angle close to the SPR plasmon resonance were also used to follow the kinetics of ferritin adsorption. Full SPR curves were measured in PBS solution and air and were used to determine the effective thickness of the ferritin layer in both environments. The ferritin layer on gold from SPR data was found to be twice as thick when measured in PBS as it was for a dry film. This difference in thickness is attributed to shrinkage of ferritin with drying. Angle-resolved XPS measurements on a dry ferritin film (preadsorbed on gold) yield a ferritin thickness of 4.7 ± 0.5 nm, a value in good agreement with those determined from QCM and SPR. QCM, SPR, and XPS all yield a surface coverage of 6.3 ± 0.7 mg m-2 for dry ferritin layers on gold. AFM enabled examination of the topography of ferritin adsorbed on gold on the nanometer scale and confirmed that ferritin forms an incomplete monolayer. In all cases, ferritin was found to be irreversibly adsorbed to gold and to form a stable protein layer, thus making it well suited as a biological receptor layer for immunosensing applications.

Journal Article↗
PubMed1999

Kinetic Study on the Formation of Colloidal Gold in the Presence of Acetylenic Glycol Nonionic Surfactant.

The formation of colloidal gold was kinetically studied using the monomer or micelle form of the acetylenic glycol nonionic surfactant Surfynol 465, which functions as a reducing and stabilizing agent. When two equal volumes of aqueous solution of Au(III) and Surfynol 465 were mixed, absorbance at the peak around 300 nm due to Au(III) rapidly decreased with time exponentially. A new peak began to appear around 530 nm, whose height sigmoidally increased with time, showing the formation of colloidal gold. From the variation in absorbance at 300 or 530 nm with time, colloidal gold formation would appear to occur through consecutive first-order reactions, Au(III) --> Au(I) --> Au(0) --> gold particle, for monomer and micelle systems. As for Au(I), the complex between Au(I) and &bond;C&tbond;C&bond; of Surfynol 465 was assigned based on reactions previously proposed for the Raman spectra of colloidal gold (Sato, S., Colloid Polym. Sci. 274, 1161 (1996)). The reaction, Au(0) --> gold particle, proceeded quickly. The overall rate of reaction was slower in the micelle system than in the monomer system. For both systems, the rate constant of the reaction Au(III) --> Au(I) exceeded the constant of the reaction Au(I) --> Au(0), and the activation energies of the two reactions were 58 kJ mol(-1). From the agreement with the activation energy of formation of colloidal gold by another method, consecutive first-order reactions, Au(III) --> Au(I) --> Au(0) --> gold particle, were considered valid for the formation of colloidal gold in the presence of Surfynol 465. Copyright 1999 Academic Press.

Journal Article↗
PubMed1993

Sensitivity and specificity of Gold types 1 to 5 anti-carcinoembryonic antigen monoclonal antibodies: immunohistologic characterization in colorectal cancer and normal tissues.

Carcinoembryonic antigen (CEA) is one of the better-studied oncodevelopmental antigens to which numerous monoclonal antibodies (MoAbs) have been generated. Many of these MoAbs have been recently grouped (Gold classification) according to their epitope recognition. The present study was designed to immunocharacterize various MoAbs, each representative of the five Gold groups, on colorectal cancers and normal tissues using semiquantitative immunohistochemistry. Sensitivity, based on the number of colorectal cancer cases (n = 100) with positive reaction (> 5% cells), was greater with Gold groups 1 and 2 (93% each) than with groups 3, 4, and 5 (78%, 83%, and 87%, respectively). The intensity of the strain also correlated with the Gold groups, with 24%, 20%, and 18% of cancer cases displaying weak or negative staining (0 or 1+) when reacted with MoAbs from groups 3, 4, and 5, respectively, versus 6% and 12% with Gold 1 and 2 antibodies. Cross-reactivity of the anti-CEA antibodies with CEA-related molecules was found to be significant with Gold 5 antibody, which stained most of the normal lung, liver, stomach, and intestinal tissues tested. Strong staining also was seen in granulocytes when they were reacted with Gold 4 and 5 antibodies. The other antibodies showed much less and variable cross-reactivity with normal tissues, with a not statistically significant advantage for Gold 1 antibodies. In addition to lower sensitivity in CEA detection, Gold 3 to 5 MoAbs were less specific due to cross-reaction with one or more of the CEA-related macromolecules expressed by normal tissues. Based on these results and given the broad clinical applications of anti-CEA MoAbs, it is essential to characterize each MoAb to be used for clinical purposes in order to avoid interpretation errors of potential relevance resulting from poor sensitivity/specificity. The use of antibodies that recognize the epitope of group 1 or 2 is recommended to maximize sensitivity and specificity for CEA detection.

Antibodies, Monoclonal↗
PubMed2006

Global Initiative on Obstructive Lung Disease (GOLD) classification of lung disease and mortality: findings from the Atherosclerosis Risk in Communities (ARIC) study.

OBJECTIVE: To determine whether a modified Global Initiative on Obstructive Lung Diseases (GOLD) classification of chronic obstructive pulmonary disease (COPD) predicts mortality in a cohort of subjects followed for up to 11 years. METHODS: We analyzed data from 15,759 adult participants, aged 43-66 years at baseline, in the Atherosclerosis Risk in Communities (ARIC) study. All baseline and follow-up data were available for 15,440 (97.9%) of the initial participants. We classified subjects using a modification of the GOLD criteria for COPD (prebronchodilator forced expiratory volume in 1s (FEV(1)) stratification of disease severity), and added a "restricted" category (FEV(1)/FVC>70% and FVC<80% predicted). We used Cox proportional hazard models to determine the risk of impaired lung function on subsequent mortality, after adjusting for age, race, sex and smoking status. RESULTS: 1242 (8.0%) subjects died by the end of 1997. The overall rate of death was 8.9 per 1000 person years, but varied from 5.4/1000 among normal subjects to 42.9/1000 among subjects with GOLD Stage 3 or 4 COPD. After adjusting for covariates, all GOLD categories, along with the restricted category, predicted a higher risk of death: GOLD Stage 3 or 4, hazard ratio (HR) 5.7, 95% confidence interval (CI) 4.4, 7.3; GOLD Stage 2 HR 2.4, 95% CI 2.0, 2.9; GOLD Stage 1 HR 1.4, 95% CI 1.1, 1.6; GOLD Stage 0 HR 1.5, 95% CI 1.3, 1.8; and restricted HR 2.3, 95% CI 1.9, 2.8. CONCLUSION: The modified GOLD classification system of COPD predicts mortality in this cohort of middle-aged Americans followed for up to 11 years.

Adult↗
PubMed2000

Gold complexes with potentially tri- and tetradentate phosphinothiolate ligands.

Reactions of [Au(PPh3)Cl], (Bu4N)[AuCl4] and the organometallic gold complex [Au(damp-C1,N)Cl2] (damp- = 2-(N,N-dimethylaminomethyl)phenyl) with the potentially tri- and tetradentate proligands PhP(C6H3-SH-2-R-3)2 (H2L1a, R = SiMe3; H2L1b, R = H) and P(C6H4-SH-2)3 (H3L2) result in the formation of mono- or dinuclear gold complexes depending on the precursor used. Monomeric complexes of the type [AuL1Cl] are formed upon the reaction with [Au(damp-C1,N)Cl2], but small amounts of dinuclear [AuL1]2 complexes with gold in two different oxidation states, +1 and +3, have been isolated as side-products. The dinuclear compounds are obtained in better yields from [AuCl4]-. A dinuclear complex having two Au(III) centers can be isolated from the reaction of [Au(PPh3)Cl] with H3L2, whereas from the reaction with H2L1b the mononuclear [Au(Ph3P)HL1b] is obtained, which contains a three-coordinate gold atom. Comparatively short gold-gold distances have been found in the dinuclear complexes (2.978(2) and 3.434(1) A). They are indicative of weak gold-gold interactions, which is unusual for gold(III).

Journal Article↗
PubMed2006

Adsorption characteristics of thionine on gold nanoparticles.

Adsorption characteristics of thionine on gold nanoparticles have been studied by using UV-vis absorption spectroscopy, fluorescence spectroscopy, transmission electron microscopy (TEM), cyclic voltammetry and Fourier transform infrared spectroscopy. With the increasing concentration of gold nanoparticles, the absorption peak intensity of H-type dimers of thionine increases continuously, whereas that of monomers of thionine first increases and then decreases. The addition of gold nanoparticles makes the equilibrium between the monomer and H-type dimer forms of thionine move toward the dimer forms. Furthermore, the adsorption behavior of thionine on gold nanoparticles is also influenced by temperature. TEM images show that the addition of thionine results in an obvious aggregation, and further support the absorption spectral results. The fluorescence intensity of adsorbed thionine is quenched by gold nanoparticles due to the electronic interaction between thionine molecules and gold nanoparticles. Cyclic voltammetric and infrared spectroscopic studies show that the nitrogen atoms of both of the NH2 moieties of thionine strongly bind to the gold nanoparticle surfaces through the electrostatic interaction of thionine with gold nanoparticles. For 15-20 nm particles, the number of adsorbed thionine molecules per gold nanoparticle is about 7.66 x 10(4). Thionine molecules can not only bind to a particle to form a compact monolayer via both of the NH2 moieties, but they can also bind to two particles via their two NH(2) moieties, respectively.

Journal Article↗
PubMed1988

Mapping gold-labeled IgE receptors on mast cells by scanning electron microscopy: receptor distributions revealed by silver enhancement, backscattered electron imaging, and digital image analysis.

Immunogold labeling and silver enhancement techniques are widely used to determine density and distribution of cell membrane receptors by light and transmission electron microscopy. However, these techniques have not been widely used for receptor detection by scanning electron microscopy. We used antigen- or protein A-conjugated colloidal gold particles, together with silver enhancement, sequential secondary and back-scattered electron imaging (SEI and BEI), and digital image processing, to explore cell surface distribution of IgE-receptor complexes on RBL-2H3 cells, a rat leukemia line that provides a model for the study of mucosal mast cells. Cells were first incubated with a monoclonal antidinitrophenol IgE (anti-DNP-IgE) that binds with high affinity to cell surface IgE receptors. The resulting IgE-receptor complexes were cross-linked either with the multivalent antigen, DNP-BSA-gold, or with a polyclonal anti-IgE antibody. Antibody-treated cells were labeled after fixation with protein A-gold. Fixed, gold-labeled cell monolayers were silver enhanced (or not), dehydrated, critical point-dried, and coated with gold-palladium (for SEI analysis) or carbon (for combined SEI/BEI analysis). They were observed in an Hitachi S800 SEM equipped with a field emission tip and a Robinson backscattered electron detector. An image processor (MegaVision 1024XM) digitized images directly from the S800 microscope at 500-1000 line resolution. Silver enhancement significantly improves detection of gold particles in both SEI and BEI modes of SEM. On gold-palladium-coated samples, 20-nm particles are resolved by SEI after enhancement. BEI resolves 15-nm particles without enhancement and 5- or 10-nm particles are resolved by BEI on silver-enhanced, carbon-coated samples. Neither BEI nor SEI alone can yield high resolution topographical maps of receptor distribution (BEI forms images on the basis of atomic number contrast which reveals gold but not surface features). Image analysis techniques were therefore introduced to digitize, enhance, and process BEI and SEI images of the same field of view. The resulting high-contrast, high-resolution images were superimposed, yielding well-resolved maps of the distribution of antigen-IgE-receptor complexes on the surface of RBL-2H3 mast cells. The maps are stored in digital form, as required for computer-based quantitative morphometric analyses. These techniques of silver enhancement, combined BEI/SEI imaging, and digital image analysis can be applied to analyze density and distribution of any gold-labeled ligand on its target cell.

Cell Line↗
PubMed1995

Does injectable gold retard radiologic evidence of joint damage in psoriatic arthritis?

The aim of this investigation has been to assess whether gold therapy prevents radiologic progression of psoriatic arthritis (PsA) over a period of 2 y. Eighteen patients (11 males, 7 females, mean age 42 y, DD 6.5 y) who were initiated on intramuscular gold during their attendance at the Psoriatic Arthritis Clinic were studied. For each gold-treated patient, 2 matched control patients, who had never had gold therapy, were identified from the PsA database. The control patients were similar to the patient population in gender, age, disease duration, number of actively inflamed joints, radiologic score and other medications used, and were followed in the clinic for at least 24 months. Actively-inflamed joint count decreased by > or = 40% in 9 of 18 gold-treated patients at 12 months. Seven patients continued gold for 24 months, while 11 discontinued gold for either lack of efficacy (4) or side effects (7). A comparison of the change in radiographic evidence of damage in the peripheral joints between the 18 gold-treated patients and the 36 controls revealed that there was no statistical difference in disease progression. These results suggest that gold therapy does not prevent the progression of damage in patients with psoriatic arthritis.

Adult↗
PubMed1980

In vitro penicillamine competition for protein-bound gold(I).

The reactions of penicillamine with gold sodium thiomalate (Myochrysine), gold-albumin complexes, and gold bound to urinary and kidney cytosolic proteins were examined. Large excesses of penicillamine (20 to 100:1 penicillamine/gold ratios) are required to mobilize significant amounts of protein bound gold. Quantitative comparisons of cysteine and penicillamine displacements of serum albumin bound gold indicate that penicillamine is approximately 5-6 times more effective than cysteine. Urinary gold is observed to be present in low molecular weight and protein bound forms, which exist in a labile chemical equilibrium and can be shifted by addition of penicillamine. These results are discussed in terms of the structure of gold(I)-penicillamine complexes and the distribution of gold(I) among protein and nonprotein thiol groups. The inappropriateness of using AuCl4- in vitro to study the biochemistry of chrysotherapy agents is delineated.

Albumins↗
PubMedDate not supplied

Mechanism of action, pharmacology, clinical efficacy and side effects of auranofin. An orally administered organic gold compound for the treatment of rheumatoid arthritis.

The mechanism of action of auranofin, an oral organic gold compound used in the treatment of rheumatoid arthritis, is probably similar to the previously available parenteral gold compounds. Auranofin affects polymorphonuclear cells and monocytes at lower concentrations than gold sodium thiomalate and generally affects humoral and cell-mediated immunity in the same direction as the latter drug. The pharmacokinetics of auranofin are different from the intramuscular gold compounds. Auranofin is 20-25% orally absorbed and has less total body retention, greater fecal excretion, and less urinary excretion than gold sodium thiomalate. This may be due in part to its differing chemistry, including its lipophilicity and monomeric structure (at least in vitro). While many clinical studies are not yet complete, auranofin (6 mg/day) is clearly more effective than placebo for treating rheumatoid arthritis. Its efficacy relative to gold sodium thiomalate is not clear. Auranofin may be slightly less effective than gold sodium thiomalate, but because it is generally less toxic than intramuscular gold compounds, its therapeutic index may be more favorable.

Administration, Oral↗
PubMed1998

Recovery and refining of Au by gold-cyanide ion biosorption using animal fibrous proteins.

Animal fibrous proteins (AFPs) such as egg-shell membrane (ESM), chicken feather (CF), wool, silk, or elastin are an intricate network of stable and water-insoluble fibers with high surface area and are abundant bioresources. Every AFP tested was found to accumulate gold-cyanide ion from aqueous solutions in high yield, depending on pH and some other parameters. Gold-cyanide ion is adsorbed by AFP at low pH range, with maximum binding observed at approx pH 2.0. Under the certain conditions, gold-cyanide ion was accumulated up to 8.6, 7.1, 9.8, 2.4, and 3.9% of dry weight on ESM, CF, wool, silk, and elastin, respectively. In the case of ESM, it was found that ESM removed gold-cyanide ion almost quantitatively and almost all the gold uptake by ESM was easily desorbed with 0.1 M NaOH. ESM can be used repeatedly for the process of gold adsorption-desorption. The gold-biosorptive capacity of ESM that was chemically modified with glutaraldehyde was higher than that of control. In column procedure, ESM packed on column removed gold-cyanide ion from the dilute aqueous solution to extremely low concentrations (nondetectable concentration of below 1 ppb).

Adsorption↗
PubMed1991

Light microscopic localization of silver-enhanced liposome-entrapped colloidal gold in mouse tissues.

Silver-enhanced liposome-entrapped colloidal gold was developed for light microscopic localization of liposomes. Preparation of colloidal gold entrapped in liposomes was achieved by a modified method of Hong, et al. (1983) Biochim. Biophys. Acta 732, 320-323). In this report, a gold chloride/citrate solution of low pH (3.4) was used to inhibit the formation of gold granules during the liposome preparation. The diameter of most liposomes ranged from 80 to 100 nm. Following liposome preparation, the pH was adjusted to 6, and the temperature increased to 55 degrees C. The majority of the liposomes contained one to three gold particles. Liposomes were injected into mice via tail vein; 24 h later, tissues were collected. Sections were processed for silver enhancement of the gold particles and examined by light microscopy. Silver-enhanced gold particles were clearly observed in both liver and implanted tumor. Localization was confirmed by electron and fluorescence microscopy. Thus, we have shown that silver enhancement of colloidal gold liposomes is a direct and sensitive method for tracing the fate of liposomes in vivo, providing minimal background interference and a good definition of various cell types.

Animals↗
PubMed1983

Gold-induced reduction in reactivity to histamine in isolated guinea pig tracheal rings.

Direct effects of gold preparations on the smooth muscle were investigated on isolated guinea pig tracheal rings. Pretreatment of the tracheal rings for 150 min with 100 microM of gold sodium thiomalate [Au(I)] significantly reduced the contraction heights induced by 4.5 microM histamine from 0.24 +/- 0.02 to 0.14 +/- 0.01 g (p less than 0.01). Gold chloride [Au(III)] was far more potent in its inhibitory effects than gold sodium thiomalate. With 15 min preincubation, gold chloride significantly suppressed the histamine-induced contraction (p less than 0.05) at such a low concentration as 10 microM (3.4 micrograms/ml). Gold chloride as well as gold sodium thiomalate did not interfere with the ciliary motion of the tracheal epithelium, whereas colchicine, having no effect on the histamine-induced contraction, did interfere with ciliary motion. These results reveal that gold itself inhibits noncaustically the guinea pig tracheal contraction induced by histamine.

Animals↗
PubMed1995

Inhibition of AP-1 binding and transcription by gold and selenium involving conserved cysteine residues in Jun and Fos.

Gold(I) salts and selenite, which have diverse therapeutic and biological effects, are noted for their reactivity with thiols. Since the binding of Jun-Jun and Jun-Fos dimers to the AP-1 DNA binding site is regulated in vitro by a redox process involving conserved cysteine residues, we hypothesized that some of the biological actions of gold and selenium are mediated via these residues. In electrophoretic mobility-shift analyses, AP-1 DNA binding was inhibited by gold(I) thiolates and selenite, with 50% inhibition occurring at approximately 5 microM and 1 microM, respectively. Thiomalic acid had no effect in the absence of gold(I), and other metal ions inhibited at higher concentrations, in a rank order correlating with their thiol binding affinities. Cysteine-to-serine mutants demonstrated that these effects of gold(I) and selenite require Cys272 and Cys154 in the DNA-binding domains of Jun and Fos, respectively. Gold(I) thiolates and selenite did not inhibit nonspecific protein binding to the AP-1 site and were at least an order of magnitude less potent as inhibitors of sequence-specific binding to the AP-2, TFIID, or NF1 sites compared with the AP-1 site. In addition, 10 microM gold(I) or 10 microM selenite inhibited expression of an AP-1-dependent reporter gene, but not an AP-2-dependent reporter gene. These data suggest a mechanism regulating transcription factor activity by inorganic ions which may contribute to the known antiarthritic action of gold and cancer chemoprevention by selenium.

Amino Acid Sequence↗
PubMed1977

Sodium aurothiomalate, gold keratinate, and various tetracyclines in mycoplasma-induced arthritis of rodents.

Sodium aurothiomalate (ATM), gold keratinate and five different tetracyclines were investigated for activity against M. arthritidis strain ATCC 14124 and M. pulmonis strain JB, both in vitro and in rodents with arthritis caused by these mycoplasmas. In vitro, ATM had only slight activity against M. arthritidis and M. pulmonis, while gold keratinate was virtually inactive against M. pulmonis. In contrast, the tetracyclines were highly active against both mycoplasmas. The tetracyclines and the gold salts were both predominantly mycoplasmastatic. In both rats and mice, parenteral administration of ATM, begun shortly before or after infection of rodents with mycoplasmas, prevented the development of arthritis. ATM or gold keratinate, given subcutaneously to mice already arthritic from infection with M. pulmonis, reduced the severity of the arthritis, even although gold keratinate was inactive aganist this mycoplasma in vitro. Moreover, direct testing of serum, collected from mice treated with gold keratinate, failed to demonstrate antimycoplasmal activity in vitro. These results suggest that the action of gold-containing drugs in mycoplasmal arthritis is due to biological properties of gold other than antimycoplasmal activity. Tetracyclines were also found to be effective in preventing arthritis in rats and mice when given subcutaneously. With high doses, subcutaneous, but not oral, therapy significantly reduced the severity of established arthritis in mice infected with M. pulmonis. The blood levels achieved with the different tetracyclines, when related to their therapeutic activity, indicated that good antimycoplasmal activity and adequate absorption from the gut were not the only properties needed for optimal effectiveness. The results are discussed in relation to treatment of rheumatoid patients with tetracycline HCl.

Administration, Oral↗
PubMed1986

Cultured human cells with high levels of gold-binding cytosolic metallothionein are not resistant to the growth inhibitory effect of sodium aurothiomalate.

We have previously shown that cells with a high content of the gold-binding protein metallothionein (MT) are resistant to the growth inhibitory effects of gold(III) chloride and auranofin. To investigate whether MT confers resistance to sodium aurothiomalate two cell lines of cultured human epithelial (HE) cells were used; the parental cell line (HE) and a substrain (HE100) containing high levels of cytosolic MT. Sodium aurothiomalate and thiomalic acid without gold both caused a dose-dependent growth inhibition of both cell lines when used in the concentration range 25-300 mumol/l culture medium and for four days' exposure. MT, despite binding about one third of the cytosolic gold, did not protect against the antiproliferative effect of sodium aurothiomalate. The gold and the thiomalate moieties were distributed differently within the cells; 30% of the cellular gold and 80% of the thiomalate were recovered in the cytosol. Gold was mainly protein bound in both cell lines, as shown by G75 Sephadex gel filtration of the cytosols. In the HE100 cells about 30% of the gold eluted with MT. The thiomalate eluted mainly with substances with molecular weights less than 1000. Cellular synthesis of MT was not observed during sodium aurothiomalate treatment. The results indicate that the sodium aurothiomalate molecule dissociates and support the suggestion that the thiomalate moiety is, in part, responsible for the antiproliferative effect of the drug.

Cadmium↗
PubMed1987

Patterns of urinary excretion of gold in patients with rheumatoid arthritis undergoing chrysotherapy.

Thirty patients receiving gold therapy for rheumatoid arthritis (RA) were studied for the urinary excretion of gold. Statistical analysis of all the urine specimens passed over a period of four days by each patient showed that a definite rhythm of gold excretion exists for each patient which is possibly related to water excretion but not to creatinine excretion. The study indicates possible reasons for the inability of earlier workers to relate gold excretion to the general body gold status of patients and suggests that as the study of 24 hour excretions of gold may be an insensitive marker of gold excretion, closer examination of individual patient rhythms of gold excretion could possibly provide a more useful method of analysis.

Adolescent↗
PubMed1988

Preparation and characterization of a colloidal gold-insulin complex with binding and biological activities identical to native insulin.

We studied the binding and biological activities of gold-insulin complexes to develop a complex with properties identical to native insulin. Stabilizing amounts of insulin absorbed to 5-, 10-, or 15-nm gold particles resulted in complexes with 40-327 insulin molecules per gold particle and 4-111 times the biological activity of unlabeled insulin, based on the molar concentration of gold complex. These data suggested that these complexes behaved as multivalent ligands. Gold-insulin complexes were prepared with 5% of the stabilizing insulin concentration and were stabilized with bovine serum albumin. This resulted in a complex with 5-7 insulin molecules per 10-nm gold particle, which stimulated glucose oxidation in rat adipocytes and competed with [125I]-insulin for binding to the insulin receptor identically to unlabeled insulin on an equimolar basis. The organization and distribution of insulin receptors occupied by this monovalent-behaving gold-insulin complex were virtually identical to previous observations using monomeric ferritin-insulin. Since multivalent ligands may affect receptor binding, re-distribution, and intracellular processing, the use of electron-dense probes that resemble the unlabeled ligand in biological and binding properties is appropriate when studying receptor dynamics of in vivo or in vitro biological systems. The gold-insulin complex developed in this study should serve this function.

Adipose Tissue↗