Surface-anchored poly(2-vinyl-4,4-dimethyl azlactone) brushes as templates for enzyme immobilization

We explored surface-anchored poly(2-vinyl-4,4-dimethyl azlactone) (PVDMA) brushes as potential templates for protein immobilization. The brushes were grown using atom transfer radical polymerization from surface-anchored initiators and characterized by a combination of ellipsometry, atomic force microscopy, and X-ray photoelectron spectroscopy. RNase A was immobilized as a model enzyme through the nucleophilic attack of azlactone by the amine groups in the lysines located in the protein. The surface density of RNase A increased linearly from 5 to 50 nm. For 50 nm thick poly(2-vinyl-4,4-dimethyl azlactone) brushes, 7.5 microg/cm2 of RNase A was bound. The kinetics and thermodynamics of RNase A immobilization, the activity relative to surface density, and the pH and temperature dependence were examined. A Langmuir-like model for binding kinetics indicates that the kinetics are controlled by the rate of adsorption of RNase A and has an adsorption rate constant, k(ads), of 2.8 x 10(-8) microg(-1) s(-1) cm3. A maximum relative activity of approximately 0.95, which is near the activity of free RNase A, was reached at 1.2 microg/cm2 (approximately 3.0 monolayers) of immobilized RNase A. The immobilized RNase A had a similar temperature and pH dependence as free RNase A, indicating no significant change in conformation. The PVDMA template was extended to other biotechnologically relevant enzymes, such as deoxyribonuclease I, glucose oxidase, glucoamylase, and trypsin, with relative activities higher than or comparable to those of enzymes immobilized by other means. PVDMA brushes offer an efficient route to immobilize proteins via the ring opening of azlactone without the need for activation or pretreatment while retaining high relative activities of the bound enzymes.     

Polymeric brushes as functional templates for immobilizing ribonuclease A: study of binding kinetics and activity

The ability to immobilize proteins with high binding capacities on surfaces while maintaining their activity is critical for protein microarrays and other biotechnological applications. We employed poly(acrylic acid) (PAA) brushes as templates to immobilize ribonuclease A (RNase A), which is commonly used to remove RNA from plasmid DNA preparations. The brushes are grown by surface-anchored atom-transfer radical polymerization (ATRP) initiators. RNase A was immobilized by both covalent esterification and a high binding capacity metal-ion complexation method to PAA brushes. The polymer brushes immobilized 30 times more enzyme compared to self-assembled monolayers. As the thickness of the brush increases, the surface density of the RNase A increases monotonically. The immobilization was investigated by ellipsometry, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), and near-edge X-ray absorption fine structure spectroscopy (NEXAFS). The activity of the immobilized RNase A was determined using UV absorbance. As much as 11.0 microg/cm(2) of RNase A was bound to PAA brushes by metal-ion complexation compared to 5.8 microg/cm(2) by covalent immobilization which is 30 and 16 times the estimated mass bound in a monolayer. The calculated diffusion coefficient D was 0.63 x 10(-14) cm(2)/s for metal-ion complexation and 0.71 x 10(-14) cm(2)/s for covalent immobilization. Similar values of D indicate that the binding kinetics is similar, but the thermodynamic equilibrium coverage varies with the binding chemistry. Immobilization kinetics and thermodynamics were characterized by ellipsometry for both methods. A maximum relative activity of 0.70-0.80 was reached between five and nine monolayers of the immobilized enzyme. However, the relative activity for covalent immobilization was greater than that of metal-ion complexation. Covalent esterification resulted in similar temperature dependence as free enzyme, whereas metal-ion complexation showed no temperature dependence indicating a significant change in conformation.     

Elastic properties of swollen polyelectrolyte gels in aqueous salt solutions

The elastic relaxation responding to a uniaxially stretched poly(acrylic acid) rodlike gel in the aqueous NaCl solution was investigated. The relaxation elucidated the shear (mu) and bulk (K) moduli and the frictional coefficients (sigma) of the fully ionized gel at pH above 9 as functions of the degree of swelling, which was controlled by the NaCl concentration (C(S)) of the solution. Two gels, cross-linked chains of which consist of 500 (GelA500) and 50 (GelA50) monomeric units, were examined to investigate the effect of the chain length on the elastic behavior. The moduli of GelA500 increased with swelling at C(S) below 100 mM and decreased at C(S) above it. The mu values of both gels can be characterized by the power function of gel diameter, d as mu proportional, variantd(beta). The beta values being -1 at C(S) above 100 mM transitionally changed to 1.2 at C(S) about 100 mM. That is, the dimensionality of space for the chains to distribute, n(dim) [= (beta+5)/(beta+2) according to the conventional theory [Sasaki et al., J. Chem. Phys. 102, 5694 (1995)]], changed from 4 (n(dim) of ideal chain) to 1.9 at C(S) = 100 mM. This indicates that the electrostatic repulsion between gel chains reduces the n(dim) at C(S) below 100 mM but not at C(S) above it. It was found that the K values of GelA500 were well described by the conventional theory but those of GelA50 not. The sigma(zr)/sigma(rr) (sigma(zr) is an off-diagonal element of the friction coefficient tensor and sigma(rr) is a diagonal element of the friction coefficient tensor) was found to be 2.7 x 10(-2), which was the same as the previously reported value for the swollen poly(acrylamide) gel [Sasaki, J. Chem. Phys. 120, 5789 (2004)]. The sigma(rr) of unit volume of the GelA500 is well explained by the free draining model while the sigma(rr) of GelA50 is less than that of the free draining model, suggesting the slip between water and ionized chain.     

具有合成核酸活性的多肽 I: C-端去四肽和去六肽核糖核酸酶A及其水解和合成活性

为寻找一个比天然RNase A分子结构更简单, 但较之具有突出的合成活性的核酸酶模型, 首先由RNase A出发, 从C-端切去不同长度的肽段, 获得了比RNase A仅有微弱水解活性但有更强合成活性的C-端去四肽和去六肽核糖核酸酶A(RAl-120和RAl-118)两种降解产物. 研究了RAl-120和RAl-118的水解活性和合成活性, 得出结论认为RNase的His119对其水解活性是重要但并非必要角色, 对其合成活性既非重要又非必要.     

Antioxidant Properties and Proximate Composition of Different Tissues of European Beaver

The chemical composition, content of cholesterol, retinol and α-tocopherol, and the total antioxidant capacity of different tissues from wild beavers were investigated. The total phenolic contents and free radical scavenging activity (DPPH and ABTS assays) were analysed spectrophotometrically, and fat-soluble vitamins were quantified using high-performance liquid chromatography. The type of tissue (skeletal muscle from loin and hind leg vs. adipose tissue from subcutaneous fat and tail) significantly affected content of all chemical components. The concentration of cholesterol was not related to total fat content. The retinol and α-tocopherol contents (µg/100 g) were significantly higher in the tail (13.0 and 391.2) and subcutaneous fat (12.2 and 371.3) compared to skeletal muscles (as an average 9.1 and 361.4). Among all tissues the tail showed significantly the highest values of DPPH (3.07 mM TE/100 g), ABTS (3.33 mM TE/100 g), and total phenolics (TPC, 543.7 mg GAE/100 g). The concentration of retinol was positively correlated with α-tocopherol (0.748, p < 0.001), and both vitamins were very strongly correlated with DPPH (0.858 and 0.886, p < 0.001), ABTS (0.894 and 0.851, p < 0.001), and TPC (0.666 and 0.913, p < 0.001). The principal component analysis proved that moisture, ash, and protein contents were representative for skeletal muscles, whereas, retinol, α-tocopherol, ABTS and DPPH accurately described the antioxidant capacity of tissue from the tail.     

Catalase adsorption onto Cibacron Blue F3GA and Fe(III)-derivatized poly(hydroxyethyl methacrylate) membranes and application to a continuous system

Poly(2-hydroxyethyl methacrylate) (poly(HEMA)) membranes were prepared by UV-initiated photopolymerization of HEMA in the presence of an initiator (a-a′-azobisisobutyronitrile, AIBN). An affinity dye, i.e. Cibacron Blue F3GA (CB) was incorporated covalently and then complexed with Fe(III) ions. The polyHEMA-CB and polyHEMA-CB-Fe(III) derivatized membranes were used in the adsorption of catalase (CAT). The enzyme-loading capability of the Fe(III)-containing membrane (23.6 μg/cm²) was greater than that of the poly(HEMA)-CB derivatized membrane (17.1 μg/cm²). The adsorption phenomena appeared to follow a typical Langmuir isotherm. The K_m values for both immobilized catalases (poly(HEMA)-CB-CAT (22.4 mM) and poly(HEMA)-CB-Fe(III)-CAT (19.3 mM)) were higher than that of free enzyme (16.5 mM). Optimum operational temperature was 5°C higher than that of the free enzyme and was significantly broader. A similar observation was made for the optimum pH. Operational, thermal and storage stabilities were found to increase with immobilization, especially in the presence of Fe(III). It was observed that enzyme could be repeatedly adsorbed and desorbed without significant loss in adsorption capacity or enzyme activity.     

Effect of ionic strength, pH and polymer concentration on the separation of DNA fragments in the presence of electroosmotic flow

DNA separations in the presence of electroosmotic flow (EOF) using poly(ethylene oxide) (PEO) solutions have been demonstrated. During the separations, PEO entered capillaries filled with Tris-borate (TB) free buffers by EOF and acted as sieving matrices. We have found that ionic strength and pH of polymer and free solutions affect the bulk EOF and resolution differently from that in capillary zone electrophoresis. The EOF coefficient increases with increasing ionic strength of the free TB buffers as a result of decreases in the adsorption of PEO molecules. In contrast, the bulk EOF decreases with increasing the ionic strength of polymer solutions using capillaries filled with high concentrations of free TB buffers. Although resolution values are high due to larger differential migration times between any two DNA fragments in a small bulk EOF using 10 mM TB buffers, use of a capillary filled with at least 100 mM TB free buffers is suggested for high-speed separations. On the side of PEO solutions, 1.5% PEO solutions prepared in 100 to 200 mM TB buffers are more proper in terms of resolution and speed. The separation of DNA markers V and VI was accomplished less than 29 min in 1.5% PEO solutions prepared in 100 mM TB buffers, pH 7.0 at 500 V/cm using a capillary filled with 10 mM free TB buffers, pH 7.0.     

Temperature-induced unfolding of ribonuclease A embedded in spherical polyelectrolyte brushes

We use Fourier Transform infrared spectroscopy (FT-IR) spectroscopy to study the thermal unfolding and refolding behavior of ribonuclease (RNase A) adsorbed to spherical polyelectrolyte brushes (SPB). The SPB consist of a solid poly(styrene) core of ca. 100 nm diameter onto which long chains of poly(styrene sulfonic acid), PSS have been densely attached. The particles bearing the adsorbed protein are dispersed in aqueous buffer solution at a pH close to the isoelectric point (9.6) of the protein. The secondary structure of the protein was analyzed by FT-IR spectroscopy and compared to the structure of the native protein before adsorption. The unfolding of the free RNase A in solution was found to be fully reversible with an unfolding temperature of 65 degrees C, in accordance to previous studies. However, after adsorption to the SPB, the unfolding temperature of the protein molecule is lowered by 10 degrees C and the Van't Hoff enthalpy of the unfolding process is significantly reduced. Moreover the unfolding of the adsorbed protein is irreversible. The phenomenon may be explained by an increase in binding sites due to unfolding of the globular structure. Protein adsorption to a spherical polyelectrolyte brush.     

Binding of muscimol-conjugated quantum dots to GABAC receptors

Functionalization of highly fluorescent CdSe/ZnS core-shell nanocrystals (quantum dots, qdots) is an emerging technology for labeling cell surface proteins. We have synthesized a conjugate consisting of approximately 150-200 muscimols (a GABA receptor agonist) covalently joined to the qdot via a poly(ethylene glycol) (PEG) linker (approximately 78 ethylene glycol units) and investigated the binding of this muscimol-PEG-qdot conjugate to homomeric rho1 GABAC receptors expressed in Xenopus oocytes. GABAC receptors mediate inhibitory synaptic signaling at multiple locations in the central nervous system (CNS). Binding of the conjugate was analyzed quantitatively by determining the fluorescence intensity of the oocyte surface membrane in relation to that of the surrounding incubation medium. Upon 5- to 10-min incubation with muscimol-PEG-qdots (34 nM in qdot concentration), GABAC-expressing oocytes exhibited a fluorescent halo at the surface membrane that significantly exceeded the fluorescence of the incubation medium. This halo was absent following muscimol-PEG-qdot treatment of oocytes lacking GABAC receptors. Incubation of the oocyte with free muscimol (100 microM-5 mM), PEG-muscimol (500 microM), or GABA (100 microM - 5 mM) substantially reduced or eliminated the fluorescence halo produced by muscimol-PEG-qdots, and the removal of GABA or free muscimol led to a recovery of muscimol-PEG-qdot binding. Unconjugated qdots and PEG-qdots that lacked conjugated muscimol neither exhibited significant binding activity nor diminished the subsequent binding of muscimol-PEG-qdots. The results indicate that muscimol joined to qdots via a long-chain PEG linker exhibits specific binding activity at the ligand-binding pocket of expressed GABAC receptors, despite the presence of both the long PEG linker and the sterically bulky qdot.     

Effect of aging, castration, and testosterone administration on ribonuclease and ribonuclease-inhibitor activities in the prostate of rats

Free ribonuclease (RNase)-inhibitor activities in both ventral and dorsal prostates had their highest peaks in 4-week-old rats and smallest peaks in around 7-week-old animals. Total RNase activity in the ventral prostate decreased overall with age, while that in the dorsal prostate increased. No significant amount of free RNase activity was found in either prostate. Weight, protein content, and free RNase-inhibitor activity in both prostates decreased after castration and increased after administration of testosterone to castrated rats. Total RNase activity in the ventral prostate was increased by castration and decreased by testosterone administration. In the dorsal prostate, total RNase activity had two peaks, 7 d after castration and 2 d after testosterone administration. A large amount of free RNase activity was found in the ventral prostate 7 d after castration and this activity was decreased by testosterone administration. In the dorsal prostate, free RNase activity was not detected after castration and testosterone administration. These results suggest that changes in the level of RNase-inhibitor in both prostates are involved in the regulation of their RNA content through the control of free RNase activity.     

Infrared photodissociation spectroscopy of V+(CO2)n and V+(CO2)nAr complexes

V+(CO2)n and V+(CO2)nAr complexes are generated by laser vaporization in a pulsed supersonic expansion. The complexes are mass-selected within a reflectron time-of-flight mass spectrometer and studied by infrared resonance-enhanced (IR-REPD) photodissociation spectroscopy. Photofragmentation proceeds exclusively through loss of intact CO2 molecules from V+(CO2)n complexes or by elimination of Ar from V+(CO2)nAr mixed complexes. Vibrational resonances are identified and assigned in the region of the asymmetric stretch of free CO2 at 2349 cm(-1). A linear geometry is confirmed for V+(CO2). Small complexes have resonances that are blueshifted from the asymmetric stretch of free CO2, consistent with structures in which all ligands are bound directly to the metal ion. Fragmentation of the larger clusters terminates at the size of n=4, and a new vibrational band at 2350 cm(-1) assigned to external ligands is observed for V+(CO2)5 and larger cluster sizes. These combined observations indicate that the coordination number for CO2 molecules around V+ is exactly four. Fourfold coordination contrasts with that seen in condensed phase complexes, where a coordination number of six is typical for V+. The spectra of larger complexes provide evidence for an intracluster insertion reaction that produces a metal oxide-carbonyl species.     

High extracellular Ca2+ alone stimulates osteoclast formation but inhibits in the presence of other osteoclastogenic factors

High ambient Ca2+ at bone resorption sites have been implicated to play an important role in the regulation of bone remodeling. The present study was performed to clarify the mode of high extracellular Ca2+ (Ca2+(e))-induced modulation of osteoclastogenesis and the expression of receptor activator of nuclear factor-kappaB ligand (RANKL) and osteoprotegerin (OPG), thereby to define its role in osteoclast formation. Mouse bone marrow cells were cocultured with osteoblastic cells in the absence or presence of osteoclastogenic factors such as 1,25-dihydroxyvitaminD3 (1,25-(OH)2vitD3)and macrophage colony-stimulating factor/soluble RANKL. Ca2+ concentration in media (1.8 mM) was adjusted to 3, 5, 7 or 10 mM. Osteoclast formation was confirmed by the appearance of tartrate-resistant acid phosphatase (TRAP)-positive multinuclear cells and the expression of osteoclast phenotypic markers (calcitonin receptor, vitronectin receptor, cathepsin K, matrix metalloproteinase-9, carbonic anhydrase 2). High Ca2+(e) alone significantly stimulated osteoclast formation in a dose-dependent manner. However, in the presence of highly osteoclastogenic factors, high Ca2+(e) significantly inhibited osteoclastogenesis. High Ca2+(e) alone continuously up-regulated RANKL expression while only transiently increased OPG expression. However, in the presence of 1,25-(OH)(2)vitD(3), high Ca2+(e) did not change the 1,25-(OH)2vitD3-induced RANKL expression while increased OPG expression. Taken together, these findings suggest that high Ca2+(e) alone increase osteoclastogenesis but inhibit in the presence of other osteoclastogenic factors. In addition, high CaCa2+(e)-induced osteoclastogenesis may be mediated by osteoblasts via up-regulation of RANKL expression. Meanwhile up-regulated OPG might participate in the inhibitory effect of high Ca2+(e) on 1,25-(OH)2vitD3-induced osteoclastogenesis.     

Inhibitors of the K+(Na+)/H+ exchanger of human red blood cells

The effect of substances as possible inhibitors of the K+(Na+)/H+ exchanger in the human red cell membrane has been tested on the (ouabain+bumetanide+EGTA)-resistant K+ influx in both physiological (HIS) and low ionic strength (LIS) solution with tracer kinetic methods. It is demonstrated that high concentrations of quinacrine (1 mM) and chloroquine (2 mM) inhibit the residual K+ influx in LIS solution to 60% and 85%, respectively, but activate it in HIS solution. Thus, chloroquine suppressed the 10-fold LIS-induced activation of the flux nearly completely. Amiloride derivatives were able to inhibit the K+ influx in both HIS and LIS solution. EIPA (75 microM) reduced the flux by about 20% and 55% in HIS and LIS solution, respectively. Newly developed drugs (HOE 642, 1 mM; HOE 694, 0.5 mM) designed to inhibit Na+/H+ exchanger isoforms showed an inhibition of the residual K+ influx of 40% and 33% in HIS and 65% and 44% in LIS solution, respectively, without haemolysis. The inhibitory effect of HOE 642 persisted in HIS (24%) and LIS (48%) solutions when Cl- was replaced by CH3SO4-. The K(+)-Cl- cotransport inhibitor DIOA (100 microM) stimulated the residual K+ influx in both solutions. It is, therefore, concluded that the K(+)-Cl- cotransporter does not contribute to the residual K+ influx both in HIS and LIS media. Okadaic acid decreased the residual K+ influx by 40% and 25% in HIS and LIS solution, respectively, showing that the residual K+ influx is affected by phosphatases like other ion transport pathways. The results show that the residual K+ influx can be decreased further by inhibiting the K+(Na+)/H+ exchanger. It remains still unclear to what extent the K+(Na+)/H+ exchanger is inhibited by the different substances used. However, the ground state membrane permeability for K+ is much smaller than assumed so far.     

Effect of added surfactant on temperature-induced gelation of emulsions

This paper involves an investigation of the effect of added ionic surfactant on the temperature-induced gelation of oil-in-water (O/W) emulsions stabilized by a responsive copolymer. The oil phase used in this study is 1-bromohexadecane. The copolymer is poly(NIPAM-co-PEGMa) (NIPAM and PEGMa are N-isopropylacrylamide and poly(ethylene glycol) methacrylate, respectively). The lower critical solution temperature for the copolymer was 39.5 degrees C. The ionic surfactant used in this work was sodium dodecylbenzenesulfonate (NaDBS). The critical association concentration for NaDBS and poly(NIPAM-co-PEGMa) was measured at 0.30 mM using fluorescence measurements (pyrene was the probe molecule). Gelation temperatures were measured for the O/W emulsions to establish the effect of added NaDBS and copolymer concentration (Cp) on the gelation temperature (Tgel). The strength of the gels was measured using dynamic oscillatory measurements. These measurements allowed the shear modulus of the gel at Tgel to be estimated as 100 Pa. A theoretical model based on transient network theory was developed that predicts the dependence of Tgel on Cp. The study revealed that NaDBS has two effects on the overall cross-link density of the emulsion gels: it contributes a source of cross-linking via micellar cross-links and also decreases the proportion of transient cross-links due to electrostatic repulsion.     

Ferrocenylnaphthalene diimide-based electrochemical ribonuclease assay.

Messenger RNA (mRNA) poly(A)+RNA (from mouse kidney) was immobilized on a N-hydroxysuccinimide(NHS)-activated carboxylic acid modified electrode prepared by the treatment of a gold electrode with 3,3'-dithiodipropionic acid, followed by NHS and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC). An electrochemical measurement using this mRNA electrode was carried out in an electrolyte containing ferrocenylnaphthalene diimide (1), and showed an electrochemical signal based on 1 concentrated on immobilized mRNA. After treating this electrode with water containing varied amounts of ribonuclease A (RNase A), the current peak based on 1 decreased with increasing in the amount of RNase A with a linear correlation in the range of 0.2-10 pg of RNase A.     

Sorption of basic dyes onto granulated pillared clays: thermodynamic and kinetic studies

Effect of the granulation process onto the thermodynamic and kinetic sorption parameters of two basic dyes (Basic Yellow 28-BY 28 and Basic Green 4-BG 4) was evaluated in the present work. The charge surface properties of the surfactant-modified aluminium-pillared clay (CTAB-Al-Mont-PILC) particles were not modified, and the isoelectric point remains constant after high shear wet granulation. The Gibbs free energy of both BY 28 and BG 4 sorption was negative and decreased with the granulation; the endothermic nature of the sorption process was confirmed by the positive values of ΔH°. Adsorption kinetics of the two dyes, studied at pH 6 and 150 mg L(-1), follow the pseudo-first order kinetic model with observed rate constants of 2.5-4.2×10(-2) min(-1). The intraparticle diffusion model, proposed by Weber and Morris, was applied, and the intraparticle plots revealed three distinct sections representing external mass transfer, intraparticle diffusion and adsorption/desorption equilibrium. Diffusion coefficients, calculated from the Boyd kinetic equation, increased with the granulation and the particle size. Pseudo-first order kinetic constants, intraparticle diffusion rate constants and diffusion coefficients were determined for two other initial concentrations (50 and 100 mg L(-1)) and include in a statistical study to evaluate the impact of granulation and initial concentration on the kinetic parameters. Kruskal-Wallis tests, Spearman's rank order correlation and factor analysis revealed a correlation between (i) the diffusion coefficients and granulation, and between (ii) the intraparticle diffusion rate constants and initial concentration.     

Calcium regulation of cardiac myofibrillar activation: effects of MgATP.

In 2 mM MgATP, 0.08 ionic strength and 1 mM free Mg++ cardiac myofibrils bound 3.5 nmoles Ca/mg protein at maximal ATPase activation. Significant amounts of Ca were also bound to cardiac myosin with these same conditions. By subtraction of this myosin-bound Ca we obtained an estimate of 4 moles Ca bound per mole of myofibrillar troponin at maximal ATPase. We found, however, that Ca activation of myofibrillar ATPase could be estimated assuming that only two of troponin's Ca-binding sites are engaged in regulation of crossbridge activity. Increases in MgMTP from 0.3 to 5.0 mM raised the free Ca, giving half-maximal isomteric tension or ATPase. Although part of this shift is most probably due to changes in the number of rigor (nucleotide-free) actin-myosin linkages, the rightward shift of the free Ca++-activation relation with increase in MgATP from 2 to 5 mM appears to be due to effects of active (nucleotide-containing) actin-myosin linkages.     

Protein separation and surfactant control of electroosmotic flow in poly(dimethylsiloxane)-coated capillaries and microchips

A thermally pyrolyzed poly(dimethylsiloxane) (PDMS) coating intended to prevent surface adsorption during capillary electrophoretic (CE) [Science 222 (1983) 266] separation of proteins, and to provide a substrate for surfactant adsorption for electroosmotic mobility control was prepared and evaluated. Coating fused-silica capillaries or glass microchip CE devices with a 1% solution of 100 cSt silicone oil in CH2Cl2, followed by forced N2 drying and thermal curing at 400 degrees C for 30 min produced a cross-linked PDMS layer. Addition of 0.01 to 0.02% Brij 35 to a 0.020 M phosphate buffer gave separations of lysozyme, cytochrome c, RNase, and fluorescein-labeled goat anti-human IgG Fab fragment. Respective plates/m typically obtained at 20 kV (740 V cm(-1)) were 2, 1.5, 1.25, and 9.4-10(5). In 50 mM ionic strength phosphate, 0.01% Brij 35 running buffer, the electroosmotic flow observed was about 25% of that in a bare capillary, and showed no pH dependence between pH 6.3-8.2. Addition of sodium dodecylsulfate (SDS) or cetyltrimethylammonium bromide (CTAB) to this running buffer allowed ready control of electroosmotic mobility, mu(eo). Concentrations of SDS between 0.005 to 0.1% resulted in mu(eo) ranging from 3 to 5 x 10(-4) cm2 V(-1) s(-1). Addition of 1 to 2.3 x 10(-4)% (2.7-6.3 microM) CTAB caused flow reversal. CTAB concentrations between 3.5 x 10(-4) and 0.05% (0.0014-1.37 mM) allowed control of mu(eo) between -1 x 10(-4) and -5.0 x 10(-4) cm2 V(-1) s(-1). For both surfactants the added presence of 0.01% Brij 35 provided slowly varying changes in mu(eo) with charged surfactant concentration.