Ristocetin

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Robert R. Montgomery - One of the best experts on this subject based on the ideXlab platform.

  • THROMBOSIS AND HEMOSTASIS e-Blood Gain-of-function GPIb ELISA assay for VWF activity in the Zimmerman Program for the Molecular and Clinical Biology of VWD
    2016
    Co-Authors: Veronica H Flood, Pamela A. Christopherson, Joan Cox Gill, Kenneth D Friedman, Patricia A Morateck, Ra L. Haberichter, Raymond G. Hoffmann, Robert R. Montgomery
    Abstract:

    von Willebrand disease (VWD) is a common bleeding disorder, but diagnosis is some-times challenging because of issues with the current von Willebrand factor (VWF) assays, VWF antigen (VWF:Ag) and VWF Ristocetin cofactor activity (VWF:RCo), used for diagnosis. We evaluated 113 healthy controls and 164 VWD subjects enrolled in the T.S. Zimmerman Program for the Molecu-lar and Clinical Biology of VWD for VWF:Ag, VWF:RCo, and a new enzyme-linked immu-nosorbent assay (ELISA)–based assay of VWF-glycoprotein Ib (GPIb) interactions us-ing a gain-of-function GPIb construct (tGPIb235Y;239V) as a receptor to bind its ligand VWF in an assay independent of Ristocetin (VWF:IbCo ELISA). Healthy con-trols, type 1, 2A, 2M, and 2N subjects had VWF:RCo/VWF:Ag ratios similar to the ratio obtained with VWF:IbCo ELISA/VWF:Ag. Type 2B VWD subjects, however, had el-evated VWF:IbCo ELISA/VWF:Ag ratios. Type 3 VWD subjects had undetectable (< 1.6 U/dL) VWF:IbCo ELISAvalues.As pre-viously reported, VWF:RCo/VWF:Ag ratio was decreased with a common A1 domain polymorphism, D1472H, as was direct bind-ing to Ristocetin for a 1472H A1 loop con-struct. The VWF:IbCo ELISA, however, was not affected by D1472H. The VWF:IbCo ELISA may be useful in testing VWF binding to GPIb, discrimination of type 2 variants, and in the diagnosis of VWD as it avoids some of the pitfalls of VWF:RCo assays. (Blood. 2011;117(6):e67-e74

  • limitations of the Ristocetin cofactor assay in measurement of von willebrand factor function
    Journal of Thrombosis and Haemostasis, 2009
    Co-Authors: Veronica H Flood, Joan Cox Gill, Robert R. Montgomery, Kenneth D Friedman, Patricia A Morateck, Jeffrey S Wren, J P Scott
    Abstract:

    Summary. Background: Type 2M von Willebrand disease (VWD) is characterized by a qualitative defect in von Willebrand factor (VWF) and diagnosed by a disproportionate decrease in VWF Ristocetin cofactor activity (VWF:RCo) as compared with VWF antigen (VWF:Ag). Objective: We report here on the spurious diagnosis of VWD in a patient with a sequence variation in the Ristocetin-binding domain of VWF. Patients/methods: The index case had a VWF:RCo of 11 IU dL )1 , with VWF:RCo/VWF:Ag ratio of 0.09. DNA sequencing revealed a novel P1467S mutation in a known Ristocetin-binding region of the A1 domain. Because of the discrepancy between the laboratory findings, consistent with type 2M VWD, and the patients lack of bleeding symptoms, further studies were performed to determine whether this mutation affected VWF function or merely reduced its ability to interact with Ristocetin. Results: Studies with recombinant VWF showed normal platelet binding with botrocetin, but a significant decrease in binding in response to Ristocetin. Ristocetininduced binding to recombinant GPIb was also absent, but normal binding was seen when a gain-of-function GPIb construct was used in the absence of Ristocetin. VWF function under shear stress was normal when analyzed with a cone and plate(let) analyzer. Conclusions: The decreased VWF:RCo seen with the P1467S sequence variation likely represents an artifact as a result of the use of Ristocetin to measure VWF activity. The normal VWF function in other assays correlates with the lack of hemorrhagic symptoms, and suggests the need for more physiologically relevant assays of VWF function.

  • Type 2M von Willebrand Disease: F606I and I662F Mutations in the Glycoprotein Ib Binding Domain Selectively Impair Ristocetin- but not Botrocetin-Mediated Binding of von Willebrand Factor to Platelets
    Blood, 1998
    Co-Authors: Cheryl A. Hillery, J. Evan Sadler, David J. Mancuso, Jay W. Ponder, Mary A. Jozwiak, Pamela A. Christopherson, Joan Cox Gill, J. Paul Scott, Robert R. Montgomery
    Abstract:

    von Willebrand disease (vWD) is a common, autosomally inherited, bleeding disorder caused by quantitative and/or qualitative deficiency of von Willebrand factor (vWF). We describe two families with a variant form of vWD where affected members of both families have borderline or low vWF antigen levels, normal vWF multimer patterns, disproportionately low Ristocetin cofactor activity, and significant bleeding symptoms. Whereas Ristocetin-induced binding of plasma vWF from affected members of both families to fixed platelets was reduced, botrocetin-induced platelet binding was normal. The sequencing of genomic DNA identified unique missense mutations in each family in the vWF exon 28. In Family A, a missense mutation at nucleotide 4105T --> A resulted in a Phe606Ile amino acid substitution (F606I) and in Family B, a missense mutation at nucleotide 4273A --> T resulted in an Ile662Phe amino acid substitution (I662F). Both mutations are within the large disulfide loop between Cys509 and Cys695 in the A1 domain that mediates vWF interaction with platelet glycoprotein Ib. Expression of recombinant vWF containing either F606I or I662F mutations resulted in mutant recombinant vWF with decreased Ristocetin-induced platelet binding, but normal multimer structure, botrocetin-induced platelet binding, collagen binding, and binding to the conformation-sensitive monoclonal antibody, AvW-3. Both mutations are phenotypically distinct from the previously reported variant type 2MMilwaukee-1 because of the presence of normal botrocetin-induced platelet binding, collagen binding, and AvW-3 binding, as well as the greater frequency and intensity of clinical bleeding. When the reported type 2M mutations are mapped on the predicted three-dimensional structure of the A1 loop of vWF, the mutations cluster in one region that is distinct from the region in which the type 2B mutations cluster.

  • dimeric Ristocetin flocculates proteins binds to platelets and mediates von willebrand factor dependent agglutination of platelets
    Journal of Biological Chemistry, 1991
    Co-Authors: J P Scott, Robert R. Montgomery, Gregory S Retzinger
    Abstract:

    Ristocetin in aqueous solution dimerizes with an equilibrium dissociation constant of 5.0 x 10(-4) M, i.e. approximately 1.1 mg ml-1 (Waltho, J.P., and Williams, D. H. (1989) J. Am. Chem. Soc. 111, 2475-2480). At concentrations of about 1.0 mg ml-1 Ristocetin flocculates many proteins, lyses platelets and, in the presence of von Willebrand factor, agglutinates both fresh and formalin-fixed platelets. Because Ristocetin exists as both monomeric and dimeric species, we sought to determine which of these forms flocculates proteins and agglutinates platelets. We found that: 1) the initial rate of flocculation of certain proteins, 2) the initial rate of agglutination of formalin-fixed platelets, and 3) the binding of Ristocetin to formalin-fixed platelets are higher order solely with respect to the concentration of Ristocetin dimers. As to the operative mechanism, it appears that bifunctional dimers cross-link proteins that possess multiple copies of a common recognition site. Preliminary evidence indicates that a recognition site is a beta-turn of the form X-P-G-X'.

Hans Deckmyn - One of the best experts on this subject based on the ideXlab platform.

  • Plasma glycocalicin as a source of GPIbα in the von Willebrand factor Ristocetin cofactor ELISA
    Thrombosis and haemostasis, 2005
    Co-Authors: Karen Vanhoorelbeke, S Vauterin, Marc Hoylaerts, Inge Pareyn, Ágota Schlammadinger, Jef Arnout, Hans Deckmyn
    Abstract:

    We have previously demonstrated that the von Willebrand factor Ristocetin cofactor activity (VWF:RCo),used in the diagnosis of vonWillebrand disease (VWD),can be accurately determined via ELISA by measuring the Ristocetin-induced binding ofVWF to a captured recombinant fragment of GPIbα (rfGPIbα ,AA 1n289) (Vanhoorelbeke et al., Thromb Haemost 2000; 83: 107-13). This ELISA is more reliable than the currently used platelet agglutination test. Normal plasma contains relatively high concentrations of glycocalicin, a proteolytic fragment of GPIbα . We therefore studied whether non-purified plasma glycocalicin can replace rfGPIbα in our ELISA. Of 42 anti-GPIbα monoclonal antibodies (MAbs) capable of binding plasma glycocalicin, only one MAb captured glycocalicin in a spatial orientation exposing theVWF-binding site in glycocalicin,allowing a specific and dose-dependent Ristocetin-mediated VWF-binding. Intra- and interassay variability were comparable with those for the rfGPIbα basedVWF:RCo ELISA.TheVWF:RCo activity of plasma from 33 normal individuals, 19 type 1, 16 type 2A, 9 type 2B, 8 type 2M and 7 type 3VWD patients was determined with this ELISA and allowed a clear identification ofVWD patients.Furthermore,determination of the VWF:RCo/VWF:Ag ratio resulted in the discrimination between type 1 and type 2 VWD patients. Results for the glycocalicin based and the rfGPIb a basedVWF:RCo ELISAs were in good agreement (r = 0.943).There was also a good correlation between the glycocalicin based ELISA and the standard platelet agglutination test (r = 0.963).In conclusion,to diagnose VWD, a VWF:RCo ELISA based on antibody immobilized plasma glycocalicin can be performed reliably.

  • characterization of murine anti glycoprotein ib monoclonal antibodies that differentiate between shear induced and Ristocetin botrocetin induced glycoprotein ib von willebrand factor interaction
    Haemostasis, 2000
    Co-Authors: Nancy Cauwenberghs, Dominique Baruch, Nadine Ajzenberg, S Vauterin, Marc Hoylaerts, Paul Declerck, Hans Deckmyn
    Abstract:

    Platelet adhesion to vascular subendothelium under conditions of high shear stress is mediated by the platelet glycoprotein (GP) Ib-von Willebrand Factor (vWF) interaction. The aim of this study was to characterize the murine monoclonal antibodies (MoAbs) 27A10 and 28E6, both raised against purified GPIb. The MoAb 27A10 is a potent inhibitor of shear-induced platelet adhesion to collagen type I in a flow chamber at shear rates of 1,300 and 2,700 s–1. 20 μg/ml of MoAb 27A10, furthermore, could completely block shear-induced aggregation in a modified Couette viscometer at shear rates of 1,000 and 4,000 s–1. On the other hand, MoAb 27A10 had a negligible effect on botrocetin-induced GPIb-vWF binding and is only a poor inhibitor of the Ristocetin-dependent interaction. In contrast, MoAb 28E6 did abolish both the Ristocetin- and botrocetin-induced GPIb-vWF binding, whereas it did not block the shear-induced interaction. Thus, we identify here two anti-GPIb MoAbs 27A10 and 28E6 that either preferentially inhibit the shear-induced or the Ristocetin/botrocetin-induced platelet-vWF interaction. With these tools it should be possible to more clearly define the mechanisms by which platelets bind to vWF in vivo.

  • a reliable and reproducible elisa method to measure Ristocetin cofactor activity of von willebrand factor
    Thrombosis and Haemostasis, 2000
    Co-Authors: Karen Vanhoorelbeke, Nancy Cauwenberghs, S Vauterin, Ágota Schlammadinger, Claudine Mazurier, Hans Deckmyn
    Abstract:

    The Ristocetin induced binding of vWF to GPIb, which is routinely tested in a platelet agglutination assay, can be reproducibly studied in an ELISA where plasma vWF binds to a captured rGPIb alpha-fragment (His1-Val289) in the presence of Ristocetin. This binding is specific since the vWF-GPIb interaction could (i) be blocked by inhibitory anti-GPIb or anti-(vWF A1 domain) monoclonal antibodies (mAbs) and (ii) be enhanced by an anti-vWF mAb that also facilitates Ristocetin induced platelet agglutination. Further studies were undertaken to determine whether the test could be used to differentiate vWF from patients with different types of von Willebrand's disease. The median vWF:RiCof activity in controls (n = 24) was 0.75 U/ml, in type 1 vWD patients (n = 17) 0.28 U/ml, in type 2A (n = 18) 0.055 U/ml, in type 2B (n = 4) 0.094 U/ml and in type 3 (n = 3) <0.0005 U/ml. Moreover, the values correlated well with those obtained from the vWF:RiCof-agglutination assay (r = 0.873). The vWF:RiCof-ELISA has several advantages: the use of a recombinant fragment instead of donor platelets results in a more reproducible test with a low inter- and intra-assay variability (<14% CV), the test can further be readily automated and for a single determination, only minimal amounts of patient plasma are required (8 microl).

J. Evan Sadler - One of the best experts on this subject based on the ideXlab platform.

  • Localization of von willebrand factor-binding sites for platelet glycoprotein Ib and botrocetin by charged-to-alanine scanning mutagenesis.
    The Journal of biological chemistry, 2000
    Co-Authors: Tadashi Matsushita, Dominique Meyer, J. Evan Sadler
    Abstract:

    At sites of vascular injury, von Willebrand factor (VWF) mediates platelet adhesion through binding to platelet glycoprotein Ib (GPIb). Previous studies identified clusters of charged residues within VWF domain A1 that were involved in binding GPIb or botrocetin. The contribution of 28 specific residues within these clusters was analyzed by mutating single amino acids to alanine. Binding to a panel of six conformation-dependent monoclonal antibodies was decreased by mutations at Asp514, Asp520, Arg552, and Arg611(numbered from the N-terminal Ser of the mature processed VWF), suggesting that these residues are necessary for domain A1 folding. Binding of 125I-botrocetin was decreased by mutations at Arg629, Arg632, Arg636, and Lys667. Ristocetin-induced and botrocetin-induced binding to GPIb both were decreased by mutations at Lys599, Arg629, and Arg632; among this group the K599A mutant was unique because 125I-botrocetin binding was normal, suggesting that Lys599 interacts directly with GPIb. Ristocetin and botrocetin actions on VWF were dissociated readily by mutagenesis. Ristocetin-induced binding to GPIb was reduced selectively by substitutions at positions Lys534, Arg571, Lys572, Glu596, Glu613, Arg616, Glu626, and Lys642, whereas botrocetin-induced binding to GPIb was decreased selectively by mutations at Arg636 and Lys667. The binding of monoclonal antibody B724 involved Lys660 and Arg663, and this antibody inhibits125I-botrocetin binding to VWF. The crystal structure of the A1 domain suggests that the botrocetin-binding site overlaps the monoclonal antibody B724 epitope on helix 5 and spans helices 4 and 5. The binding of botrocetin also activates the nearby VWF-binding site for GPIb that involves Lys599 on helix 3.

  • Type 2M von Willebrand Disease: F606I and I662F Mutations in the Glycoprotein Ib Binding Domain Selectively Impair Ristocetin- but not Botrocetin-Mediated Binding of von Willebrand Factor to Platelets
    Blood, 1998
    Co-Authors: Cheryl A. Hillery, J. Evan Sadler, David J. Mancuso, Jay W. Ponder, Mary A. Jozwiak, Pamela A. Christopherson, Joan Cox Gill, J. Paul Scott, Robert R. Montgomery
    Abstract:

    von Willebrand disease (vWD) is a common, autosomally inherited, bleeding disorder caused by quantitative and/or qualitative deficiency of von Willebrand factor (vWF). We describe two families with a variant form of vWD where affected members of both families have borderline or low vWF antigen levels, normal vWF multimer patterns, disproportionately low Ristocetin cofactor activity, and significant bleeding symptoms. Whereas Ristocetin-induced binding of plasma vWF from affected members of both families to fixed platelets was reduced, botrocetin-induced platelet binding was normal. The sequencing of genomic DNA identified unique missense mutations in each family in the vWF exon 28. In Family A, a missense mutation at nucleotide 4105T --> A resulted in a Phe606Ile amino acid substitution (F606I) and in Family B, a missense mutation at nucleotide 4273A --> T resulted in an Ile662Phe amino acid substitution (I662F). Both mutations are within the large disulfide loop between Cys509 and Cys695 in the A1 domain that mediates vWF interaction with platelet glycoprotein Ib. Expression of recombinant vWF containing either F606I or I662F mutations resulted in mutant recombinant vWF with decreased Ristocetin-induced platelet binding, but normal multimer structure, botrocetin-induced platelet binding, collagen binding, and binding to the conformation-sensitive monoclonal antibody, AvW-3. Both mutations are phenotypically distinct from the previously reported variant type 2MMilwaukee-1 because of the presence of normal botrocetin-induced platelet binding, collagen binding, and AvW-3 binding, as well as the greater frequency and intensity of clinical bleeding. When the reported type 2M mutations are mapped on the predicted three-dimensional structure of the A1 loop of vWF, the mutations cluster in one region that is distinct from the region in which the type 2B mutations cluster.

  • Identification of Amino Acid Residues Essential for von Willebrand Factor Binding to Platelet Glycoprotein Ib. CHARGED-TO-ALANINE SCANNING MUTAGENESIS OF THE A1 DOMAIN OF HUMAN VON WILLEBRAND FACTOR
    The Journal of biological chemistry, 1995
    Co-Authors: Tadashi Matsushita, J. Evan Sadler
    Abstract:

    At sites of vascular injury, von Willebrand factor (VWF) mediates platelet adhesion through binding to platelet glycoprotein Ib (GPIb). The VWF-GPIb interaction was investigated by clustered charged-to-alanine scanning mutagenesis of VWF domain A1 between His-473 and Gly-716. Recombinant variants of VWF were assayed for binding to conformation-dependent monoclonal antibody NMC-4, for Ristocetin-induced and botrocetin-induced binding to platelets, and for direct binding to botrocetin. Substitutions at 32 amino acids had no effect on VWF function. The epitope of NMC-4 depended on charged residues between Asp-514 and Arg-632 and not on segments previously implicated by peptide inhibition studies, Cys-474-Pro-488 and Leu-694-Pro-708. Substitutions at Glu-626 and in the segment Asp-520-Lys-534 abolished Ristocetin-induced binding of VWF to GPIb but did not affect botrocetin-induced binding, suggesting that these regions are required for modulation by Ristocetin but not for binding of VWF to GPIb. Mutations at Glu-596 and Lys-599 decreased binding of VWF to GPIb without affecting its binding to botrocetin, suggesting that this segment interacts directly with GPIb. Alanine substitutions at Arg-545 and in the segments Glu-497-Arg-511 and Arg-687-Glu-689 caused increased binding of VWF to GPIb. These results, and the locations of von Willebrand disease type 2B mutations, suggest that two acidic regions containing the Cys-509-Cys-695 disulfide (Glu-497-Arg-511, Arg-687-Val-698) and one predominantly basic region (Met-540-Arg-578) cooperate to inhibit a distinct GPIb binding site in the VWF A1 domain. This inhibition is relieved by specific mutations, by the modulators Ristocetin and botrocetin, or by binding to subendothelial connective tissue.

J. E. Sadler - One of the best experts on this subject based on the ideXlab platform.

  • von Willebrand disease type B: a missense mutation selectively abolishes Ristocetin-induced von Willebrand factor binding to platelet glycoprotein Ib.
    Proceedings of the National Academy of Sciences of the United States of America, 1992
    Co-Authors: I Rabinowitz, Elodee A. Tuley, David J. Mancuso, A M Randi, B G Firkin, M A Howard, J. E. Sadler
    Abstract:

    Abstract von Willebrand factor (vWF) is a multimeric glycoprotein that mediates the adhesion of platelets to the subendothelium by binding to platelet glycoprotein Ib. For human vWF, this interaction can be induced in vitro by the antibiotic Ristocetin or the snake venom protein botrocetin. A missense mutation, Gly-561-->Ser, was identified within the proposed glycoprotein Ib binding domain of vWF in the proband with von Willebrand disease type B, a unique variant characterized by no Ristocetin-induced, but normal botrocetin-induced, binding to glycoprotein Ib. The corresponding mutant recombinant protein, rvWF(G561S), formed normal multimers and exhibited the same functional defect as the patient's plasma vWF, confirming that this mutation causes von Willebrand disease type B. These data show that botrocetin and Ristocetin cofactor activities of vWF can be dissociated by a point mutation and confirm that these mediators promote vWF binding to platelets by different mechanisms. The normal botrocetin-induced binding and the defective Ristocetin-induced binding of rvWF(G561S) suggest that the primary defect in von Willebrand disease type B may be a failure of normal allosteric regulation of the glycoprotein Ib binding function of vWF.

Daniel W. Armstrong - One of the best experts on this subject based on the ideXlab platform.

  • avoparcin a new macrocyclic antibiotic chiral run buffer additive for capillary electrophoresis
    Electrophoresis, 1999
    Co-Authors: Helen K Ekborgott, Kyung Hyun Gahm, Gina A Zientara, Jeffrey M Schneiderheinze, Daniel W. Armstrong
    Abstract:

    Avoparcin, like vancomycin, teicoplanin, and Ristocetin A, belongs to the family of macrocyclic glycopeptide antibiotics. These antibiotics have all been used as effective chiral selectors for capillary electrophoresis (CE), thin-layer chromatography (TLC), and high performance liquid chromatography (HPLC). The present work focuses on avoparcin, which has been shown to be an excellent chiral selector for the CE enantioseparation of many N-blocked amino acids, as well as several anti-inflammatory drugs of pharmaceutical importance. The use of avoparcin as a chiral run buffer additive in CE is discussed, as well as the effects of changing experimental parameters, like avoparcin concentration, pH, organic modifiers, etc. Comparisons of enantioseparations of some N-3,5-dinitrobenzoyl-derivatized amino acids, using either avoparcin, Ristocetin A, teicoplanin, or vancomycin in the run buffer, are also made. In general, vancomycin had the longest migration times, and Ristocetin A the shortest, while avoparcin was intermediate. Generally, at least one of the four chiral selectors produced an excellent separation, while a different macrocyclic antibiotic produced a poor separation. Currently, we see no way to predict which chiral run buffer additive will be best or worst for an individual solute.

  • highly enantioselective hplc separations using the covalently bonded macrocyclic antibiotic Ristocetin a chiral stationary phase
    Chirality, 1998
    Co-Authors: Helen K Ekborgott, Youbang Liu, Daniel W. Armstrong
    Abstract:

    The macrocyclic glycopeptide, Ristocetin A, was covalently bonded to a silica gel support and evaluated as a liquid chromatographic (LC) chiral stationary phase (CSP). Over 230 racemates were resolved in either the reversed-phase mode, the normal-phase mode, or the polar-organic mode. The retention behavior and selectivity of this CSP were examined in each mode. Optimization of separations on this column is discussed. The Ristocetin A CSP appeared to be complimentary to other glycopeptide CSPs (i.e., vancomycin and teicoplanin). Column stability was excellent. The CSP was not irreversibly altered when going from one mobile phase mode to another. Chirality 10:434–483, 1998. © 1998 Wiley-Liss, Inc.

  • comparison and modeling study of vancomycin Ristocetin a and teicoplanin for ce enantioseparations
    International Journal of Computer Vision, 1996
    Co-Authors: Mary P Gasper, Alain Berthod, Usha B Nair, Daniel W. Armstrong
    Abstract:

    The structurally related glycopeptide antibiotics vancomycin, Ristocetin A, and teicoplanin can all be used as chiral selectors in capillary electrophoresis (CE). Both experimental and modeling studies were done to elucidate their similarities and differences. There are identifiable morphological differences in the aglycon macrocyclic portions of these three compounds. In addition, there are other structural distinctions that can affect their CE enantioselectivity, migration times, and efficiency. Teicoplanin is the most distinct of the three and is the only one that is surface active. Its aggregational properties appear to affect its enantioselectivity among other things. The similar but not identical structures of the three glycopeptides produce similar but not identical enantioselectivities. This leads to the empirically useful “principle of complementary separations”, in which a partial resolution with one chiral selector can be brought to baseline with one of the others. Overall, Ristocetin A appears...

  • highly enantioselective capillary electrophoretic separations with dilute solutions of the macrocyclic antibiotic Ristocetin a
    Journal of Chromatography A, 1995
    Co-Authors: Daniel W. Armstrong, Mary P Gasper, Kimber L Rundlett
    Abstract:

    Ristocetin A is one of a series of structurally related amphoteric, glycopeptide, macrocyclic antibiotics. These compounds have several features that make them attractive as chiral selectors. These include spatially oriented functional groups that are known to provide the types of interactions that are conducive to enantio-recognition, a somewhat rigid "pocket" that can provide a site for hydrophobic interactions and polar, flexible arms (i.e., pendent sugar moieties) that can rotate to hydrogen bond and otherwise interact with a variety of chiral analytes. In addition, these compounds are sufficiently soluble in water, aqueous buffers and aqueous-organic solvents that are commonly used in capillary electrophoresis (CE). The use and optimization of Ristocetin A as a chiral selector in CE is discussed. Over 120 racemates are resolved including a variety of N-blocked amino acids, non-steroidal anti-inflammatory compounds and a large number of biologically important compounds containing carboxylic acid groups (e.g., mandelic acid derivatives, lactic acid derivatives, folinic acid, tropic acid).