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Kim D Janda

Publications and source records attributed to Kim D Janda.

At least 91 records · Page 5Linked to original sources
PubMed2003

Evidence for the production of trioxygen species during antibody-catalyzed chemical modification of antigens.

Recent work in our laboratory showed that products formed by the antibody-catalyzed water-oxidation pathway can kill bacteria. Dihydrogen peroxide, the end product of this pathway, was found to be necessary, but not sufficient, for the observed efficiency of bacterial killing. The search for further bactericidal agents that might be formed along the pathway led to the recognition of an oxidant that, in its interaction with chemical probes, showed the chemical signature of ozone. Here we report that the antibody-catalyzed water-oxidation process is capable of regioselectively converting antibody-bound benzoic acid into para-hydroxy benzoic acid as well as regioselectively hydroxylating the 4-position of the phenyl ring of a single tryptophan residue located in the antibody molecule. We view the occurrence of these highly selective chemical reactions as evidence for the formation of a short-lived hydroxylating radical species within the antibody molecule. In line with our previously presented hypothesis according to which the singlet-oxygen ((1)O*(2)) induced antibody-catalyzed water-oxidation pathways proceeds via the formation of dihydrogen trioxide (H(2)O(3)), we now consider the possibility that the hydroxylating species might be the hydrotrioxy radical HO(3)*, and we point to the remarkable potential of this either H(2)O(3)- or O(3)-derivable species to act as a masked hydroxyl radical HO* in a biological environment.

Animals↗
PubMed2002

Evidence for antibody-catalyzed ozone formation in bacterial killing and inflammation.

Recently, we showed that antibodies catalyze the generation of hydrogen peroxide (H2O2) from singlet molecular oxygen (1O2*) and water. Here, we show that this process can lead to efficient killing of bacteria, regardless of the antigen specificity of the antibody. H2O2 production by antibodies alone was found to be not sufficient for bacterial killing. Our studies suggested that the antibody-catalyzed water-oxidation pathway produced an additional molecular species with a chemical signature similar to that of ozone. This species is also generated during the oxidative burst of activated human neutrophils and during inflammation. These observations suggest that alternative pathways may exist for biological killing of bacteria that are mediated by potent oxidants previously unknown to biology.

Animals↗
PubMed2002

A previously undescribed chemical link between smoking and metabolic disease.

Over the past 20 years, protein glycation has been implicated in a variety of pathological states. Although smoking also can contribute to many of these diseases, the precise mechanism by which this occurs is not known. Previously, we have demonstrated that nornicotine, a constituent of tobacco and metabolite of nicotine, can catalyze aldol reactions under aqueous conditions. This finding has caused us to question whether this reaction has physiological consequences. We now report that nornicotine causes aberrant protein glycation and catalyzes the covalent modification of certain prescription drugs such as the commonly used steroid, prednisone. Furthermore, we show that the plasma of smokers as compared with nonsmokers contains higher concentrations of nornicotine-modified proteins, suggesting an unrecognized pathway for the development of the pathology of tobacco abuse.

Glycation End Products, Advanced↗
PubMed2002

Phage-display selection of a human single-chain fv antibody highly specific for melanoma and breast cancer cells using a chemoenzymatically synthesized G(M3)-carbohydrate antigen.

Overexpression of the cell-surface glycosphingolipid G(M3) is associated with a number of different cancers, including those of the skin, colon, breast, and lung. Antibodies against the G(M3) epitope have potential application as therapeutic agents in the treatment of these cancers. We describe the chemoenzymatic synthesis of two G(M3)-derived reagents and their use in the panning of a phage-displayed human single-chain Fv (scFv) antibody library derived from the blood of cancer patients. Three scFv-phage clones, GM3A6, GM3A8, and GM3A15, were selected for recombinant expression and were characterized using BIAcore and flow cytometry. BIAcore measurements using the purified, soluble scFvs yielded dissociation constants (K(d)) ranging from 4.2 x 10(-7) to 2.1 x 10(-5) M. Flow cytometry was used to evaluate the ability of each scFv to discriminate between normal human cells (human dermal fibroblast, HDFa), melanoma cells (HMV-1, M21, and C-8161), and breast cancer cells (BCM-1, BCM-2, and BMS). GM3A6 displayed cross-reactivity with normal cells, as well as tumor cells, and GM3A15 possessed little or no binding activity toward any of the cell lines tested. However, GM3A8 bound to five of the six tumor cell lines and showed no measurable reactivity against the HDFa cells. Hence, we have demonstrated that a synthetic G(M3) panning reagent can be used to isolate a fully human scFv that is highly specific for native G(M3) on the surface of tumor cells. The result is a significant step toward effective immunotherapies for the treatment of cancer.

Amino Acid Sequence↗
PubMed2002

A method for the generation of combinatorial antibody libraries using pIX phage display.

For more than a decade, phage displayed combinatorial antibody libraries have been used to generate and select a wide variety of antibodies. We previously reported that the phage coat proteins pVII and pIX could be used to display the heterodimeric structure of the antibody Fv region. Herein, aspects of this technology were invoked and extended to construct a large, human single-chain Fv (scFv) library of 4.5 x 10(9) members displayed on pIX of filamentous bacteriophage. Furthermore, the diversity, quality, and utility of the library were demonstrated by the selection of scFv clones against six different protein antigens. Notably, more than 90% of the selected clones showed positive binding for their respective antigens after as few as three rounds of panning. Analyzed scFvs were also found to be of high affinity. For example, kinetic analysis (BIAcore) revealed that scFvs against staphylococcal enterotoxin B and cholera toxin B subunit had a nanomolar and subnanomolar dissociation constant, respectively, affording affinities comparable to, or exceeding that, of mAbs obtained from immunization. High specificity was also attained, not only between very distinct proteins, but also in the case of the Ricinus communis ("ricin") agglutinins (RCA(60) and RCA(120)), despite >80% sequence homology between the two. The results suggested that the performance of pIX-display libraries can potentially exceed that of the pIII-display format and make it ideally suited for panning a wide variety of target antigens.

Bacteriophages↗
PubMed2002

Syntheses of dendritic linkers containing chlorambucil residues for the preparation of antibody-multidrug immunoconjugates.

A novel dendritic molecule with nine chlorambucil (CBL) residues on the surface and a maleimide moiety at the core terminus was synthesized using a convergent synthetic methodology. This molecule is ready for attachment to single-chain Fv antibodies (scFvs) to form antibody-multidrug immunoconjugates in an effort to study the relevance of drug/antibody molar ratio and the potency of these drug-antibody immunoconjugates. A monomer and a trimer with a similar structural motif were also prepared for comparative purposes.

Antibodies↗
PubMed2002

Preparation of soluble and insoluble polymer supported IBX reagents.

A series of soluble and insoluble polymer supported versions of the versatile oxidizing reagent IBX has been prepared. Each of the reagents were evaluated for their efficiency in the conversion of benzyl alcohol to benzaldehyde. Results from this study were that the soluble, non-crosslinked polystyrene supported IBX reagent gave the best rate of conversion to benzaldehyde, while the macroporous polymer supported IBX resin provided a superior rate of conversion to benzaldehyde when compared with a gel type resin. The macroporous IBX reagent was also shown to convert a series of alcohols to the corresponding aldehydes and ketones.

Benzaldehydes↗
PubMed2002

A parallel approach to the discovery of carrier delivery vehicles to enhance antigen immunogenicity.

As part of an ongoing effort to generate human and murine monoclonal antibodies against poorly immunogenic tumor-associated antigens we have merged the rapidly expanding disciplines of parallel polymer synthesis and controlled-release technology with immunology to produce a rapid and generic approach to improve the immunogenicity of carrier-bound antigens. The process involves three stages: An array of cross-linked hydrogel materials containing a carrier protein (at various concentrations) is prepared in parallel in one step. The array is then screened in mice to determine the most effective hydrogel at enhancing the immunogenicity of the encapsulated versus nonencapsulated carrier. Finally, the most efficient hydrogel is prepared containing the critical carrier-antigen conjugate and is used for immunization protocols. The strategy was successful for the BSA-glycoconjugate of the tumor-associated antigen GM3 analogue 4. When encapsulated within the hydrogel array member most efficient at elevating BSA immunogenicity, the BSA-4 glycoconjugate was significantly more immunogenic that when administered as a free antigen.

Animals↗
PubMed2002

Preparation of new microgel polymers and their application as supports in organic synthesis.

A series of soluble microgel polymers have been synthesized using solution-phase polymerization reactions. In a systematic manner, several variables such as monomer concentration, cross-linker content, reaction solvent and reaction time were examined, and this provided an optimal polymer with both solubility and precipitation characteristics suitable for synthetic applications. Thus, a chemically functionalized microgel polymer was synthesized, and the utility of this polymer in the synthesis of a small array of oxazole compounds has been demonstrated. The advantage of the microgel polymers produced was that they exhibited solution viscosities lower than those of conventional linear polymers even at higher concentrations, and this was found to be beneficial for their precipitation properties. Compounds prepared using the described microgel polymer supports were obtained in similar yields and purity when compared with insoluble resins, and more importantly, the soluble polymer bound intermediates could be analyzed at each step using standard NMR techniques.

Catalysis↗
PubMed2002

Human antibodies against spores of the genus Bacillus: a model study for detection of and protection against anthrax and the bioterrorist threat.

A naive, human single-chain Fv (scFv) phage-display library was used in bio-panning against live, native spores of Bacillus subtilis IFO 3336 suspended in solution. A direct in vitro panning and enzyme-linked immunosorbent assay-based selection afforded a panel of nine scFv-phage clones of which two, 5B and 7E, were chosen for further study. These two clones differed in their relative specificity and affinity for spores of B. subtilis IFO 3336 vs. a panel of spores from 11 other Bacillus species/strains. A variety of enzyme-linked immunosorbent assay protocols indicated these scFv-phage clones recognized different spore epitopes. Notably, some spore epitopes markedly changed between the free and microtiter-plate immobilized state as revealed by antibody-phage binding. An additional library selection procedure also was examined by constructing a Fab chain-shuffled sublibrary from the nine positive clones and by using a subtractive panning strategy to remove crossreactivity with B. licheniformis 5A24. The Fab-phage clone 52 was improved compared with 5B and was comparable to 7E in binding B. subtilis IFO 3336 vs. B. licheniformis 5A24, yet showed a distinctive crossreactivity pattern with other spores. We also developed a method to directly detect individual spores by using fluorescently labeled antibody-phage. Finally, a variety of "powders" that might be used in deploying spores of B. anthracis were examined for antibody-phage binding. The strategies described provide a foundation to discover human antibodies specific for native spores of B. anthracis that can be developed as diagnostic and therapeutic reagents.

Anthrax↗
PubMed2002

Synthesis, properties, and reactivity of cocaine benzoylthio ester possessing the cocaine absolute configuration.

One aspect of immunopharmacotherapy for cocaine abuse involves the use of a catalytic monoclonal antibody (mAb) to degrade cocaine via hydrolysis of the benzoate ester. A cocaine benzoylthio ester analogue provides a means to implement high-throughput selection strategies to potentially isolate mAbs with high activity. The required analogue was synthesized starting from (-)-cocaine hydrochloride and possessed the cocaine absolute configuration. Key points in the preparation were the introduction of the sulfur atom at C-3 via a bromomagnesium thiolate addition to the exo face of anhydroecgonine, separation of C-2 diastereomers, recycling of a C-2 thio ester byproduct, and formation of the necessary C-2 methyl and C-3 benzoylthio esters. Effects resulting from the lower electronegativity and greater hydrophobicity of sulfur compared to oxygen were observed. These characteristics could result in interesting drug properties. Furthermore, the analogue was found to be a substrate for catalytic mAbs that hydrolyze cocaine as monitored by HPLC and also spectrophotometry by coupling cleavage of the benzoylthio ester to the disulfide exchange with Ellman's reagent. Screening antibody libraries with the new cocaine analogue using the spectroscopic assay provides an avenue for the high-throughput identification of catalysts that efficiently breakdown cocaine.

Antibodies, Catalytic↗
PubMed2002

Aqueous aldol catalysis by a nicotine metabolite.

Nornicotine, an endogenous tobacco alkaloid and minor nicotine metabolite, can catalyze aldol reactions at physiological pH. Catalysis appears to be due to a covalent enamine mechanism, an unprecedented reaction with small organic molecule catalysts in aqueous buffer. Kinetic parameters for nornicotine as well as other related alkaloids were measured and demonstrate that both the pyrrolidine and pyridine rings are critical for optimal catalysis. Substrate compatibility of this catalyst and its implications in vivo are discussed.

Acetone↗
PubMed2002

Antibody-catalyzed cleavage of the D-Ala-D-Lac depsipeptide: an immunological approach to the problem of vancomycin resistance.

Vancomycin resistance is currently a major healthcare problem. The development of a catalytic monoclonal antibody (mAb) that hydrolyzes the D-Ala-D-Lac depsipeptide provides a potentially novel antibiotic strategy. A phosphonate hapten design was used to program antibody catalysis. The characteristics of the hapten were shown to be important for obtaining a viable immune response and several catalytic mAbs that cleave a peptidoglycan model substrate. The best mAb afforded a >500-fold rate enhancement over background.

Animals↗
PubMed2002

A cofactor approach to copper-dependent catalytic antibodies.

A strategy for the preparation of semisynthetic copper(II)-based catalytic metalloproteins is described in which a metal-binding bis-imidazole cofactor is incorporated into the combining site of the aldolase antibody 38C2. Antibody 38C2 features a large hydrophobic-combining site pocket with a highly nucleophilic lysine residue, Lys(H93), that can be covalently modified. A comparison of several lactone and anhydride reagents shows that the latter are the most effective and general derivatizing agents for the 38C2 Lys residue. A bis-imidazole anhydride (5) was efficiently prepared from N-methyl imidazole. The 38C2-5-Cu conjugate was prepared by either (i) initial derivatization of 38C2 with 5 followed by metallation with CuCl2, or (ii) precoordination of 5 with CuCl2 followed by conjugation with 38C2. The resulting 38C2-5-Cu conjugate was an active catalyst for the hydrolysis of the coordinating picolinate ester 11, following Michaelis-Menten kinetics [kcat(11) = 2.3 min(-1) and Km(11) 2.2 mM] with a rate enhancement [kcat(11)k(uncat)(11)] of 2.1 x 10(5). Comparison of the second-order rate constants of the modified 38C2 and the Cu(II)-bis-imidazolyl complex k(6-CuCl2) gives a rate enhancement of 3.5 x 10(4) in favor of the antibody complex with an effective molarity of 76.7 M, revealing a significant catalytic benefit to the binding of the bis-imidazolyl ligand into 38C2.

Anhydrides↗
PubMed2002

Histidine kinases as targets for new antimicrobial agents.

The emergence and spread of hospital acquired multi drug resistant bacteria present a need for new antibiotics with innovative mode of action. Advances in molecular microbiology and genomics have led to the identification of numerous bacterial genes coding for proteins that could potentially serve as targets for antibacterial compounds. Histidine kinase promoted two-component systems are extremely common in bacteria and play an important role in essential signal transduction for adapting to bacterial stress. Since signal transduction in mammals occurs by a different mechanism, inhibition of histidine kinases could be a potential target for antimicrobial agents. This review will summarize our current knowledge of the structure and function of histidine kinase and the development of antibiotics with a new mode of action: targeting histidine kinase promoted signal transduction and its subsequent regulation of gene expression system.

Anti-Bacterial Agents↗
PubMed2002

Polyene substrates with unusual methylation patterns to probe the active sites of three catalytic antibodies.

The synthesis of two tetraenes that differ in their methylation pattern from the natural substrate in lanosterol biosynthesis, 2,3-oxidosqualene, and their examination with three catalytic antibodies is described. The design of these novel, linear terpenoid structures was governed by initial results obtained from the characterization of the three catalytic antibodies. These were generated by immunization with a steroidal hapten that mimics multicyclization without the necessity for anti-Markovnikov additions or ring expansions. Such a reaction cascade would represent a more 'primitive' version compared to the oxidosqualene cyclization observed in lanosterol, cycloartenol and beta-amyrin biosynthesis and would not require a tail-to-tail connection of the third and fourth isoprene unit as seen in squalene. The first tetraene design (A) only contains trisubstituted double bonds and hence its synthesis starts from farnesol and tris-norgeraniol. The second tetraene design (B) is considered the more precise match to the inducing hapten that generated the antibody collections by exhibiting one disubstituted double bond and its synthesis utilizes a tris-norgeraniol derivative and a symmetrical bis-allylic alcohol as key building blocks. Chromatographic comparison studies lead to the conclusion that the currently studied antibodies also produce monocyclic products from the two substrates as has been formerly observed with a squalene-derived substrate. In contrast, 2,3-oxidosqualene is not accepted by these catalysts supporting the notion that the current substrates are fully bound by recognition of both terminal functional groups.

Antibodies, Catalytic↗