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B S Green

Publications and source records attributed to B S Green.

26 records · Page 2Linked to original sources
PubMed1993

Prevention of high- and low-dose STZ-induced diabetes with D-glucose and 5-thio-D-glucose.

To induce hyperglycemia in mice by administration of STZ, two experimental protocols that involve different pathogenic pathways are being used. First, the intraperitoneal injection of a single high dose (HD-STZ) exerts direct toxicity on beta-cells, which results in necrosis within 48-72 h and overt permanent hyperglycemia. Second, injections of multiple low doses of STZ (LD-STZ), administered intraperitoneally on 5 consecutive days, induce both beta-cytotoxic effects and STZ-specific T-cell-dependent immune reactions. In LD-STZ models, only a combination of toxic and immunological effects result in gradually increasing hyperglycemia, provided male mice of susceptible strains are being used. In this study, we found that 5-T-G, a glucose analogue that has sulfur for oxygen in the pyranose ring, prevented, in a dose-dependent way, both HD-STZ- and LD-STZ-induced hyperglycemia and that D-G, which was only tested in the LD-STZ system, was also protective, albeit somewhat less so than 5-T-G. This protective effect was achieved by intraperitoneally injecting 5-T-G and D-G, respectively, right before each STZ injection. Protection against hyperglycemia was already achieved with a total of 3 injections of 5-T-G, 1 injection each given before the first 3 of 5 LD-STZ injections. By means of OGTT, it was determined that pretreatment with 5-T-G afforded protection from substantial beta-cell damage in vivo.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Detection of catalytic monoclonal antibodies.

Several laboratories have now shown that monoclonal antibodies having enzyme-like properties can be generated. The generation of catalytic antibodies makes use of the same basic procedures that have been used for the generation of binding monoclonal antibodies, yet the process involves an additional crucial step: screening for catalytic activity. In this paper we address the unique problems involved in the detection of inefficient catalytic activity that is accompanied by uncatalyzed background reaction. An analysis that allows optimization of assay conditions and estimation of the minimal antibody concentration required to observe catalysis is presented. The results indicate that the structure of the substrate should be optimized to increase its affinity (i.e., decrease its Km) and reduce its concentration to pseudo-first-order conditions (S(O) much less than Km) so that the signal observed in the presence of a catalytic antibody (delta Pcat) is significantly higher than that of the background (delta P(uncat)). Other factors involved in the screening procedures, e.g., sensitivity of the assay, solubility and reactivity of the substrate, and purity of the antibody preparation, are also discussed. The effect of these assay parameters on the ability to detect catalytic activity is demonstrated with p-nitrophenyl ester-hydrolyzing antibodies.

Animals↗
PubMed1991

Catalytic antibodies and biomimetics.

Of the various approaches being studied to mimic the catalytic properties of enzymes, catalytic antibody research is advancing most rapidly and successfully; the discovery of new reactions and new catalytic antibody-producing haptenic structures continues unabated. One of the highlights of the past year was the design and synthesis of a catalytically active peptide. The overall area of catalytic antibodies and biomimetics will be prominent in future biotechnological applications, as further advances are made and the nature of the catalyzed reactions becomes better understood.

Antibodies↗
PubMed1990

Simple method for selecting catalytic monoclonal antibodies that exhibit turnover and specificity.

Monoclonal antibodies were raised against a mono-p-nitrophenyl phosphonate ester to elicit catalytic antibodies capable of hydrolyzing the analogous p-nitrophenyl ester or carbonate. Potential catalytic antibody producing clones were selected, by use of a competitive inhibition assay, on the basis of their affinity for a "short" transition-state analogue, a truncated hapten which maximizes the relative contribution of the transition-state structural elements to binding. Of 30-40 clones that would have been examined on the basis of hapten binding alone, 7 were selected and 4 of these catalyzed the hydrolysis of the relevant p-nitrophenyl ester. This competitive inhibition technique represents a general approach for selecting potential catalytic antibodies and significantly increases the probability of obtaining efficient catalytic monoclonal antibodies. Further study of the catalytic antibodies revealed significant rate enhancement (kcat/kuncat approximately 10(4)) and substrate specificity for the hydrolysis of the analogous ester and, for three of the antibodies, of the analogous carbonate. The antibodies displayed turnover, an essential feature of enzymes. Evidence that catalysis occurred at the antibody combining sites was provided by the identity of the binding and the catalysis-inhibition specificity patterns.

Antibodies, Monoclonal↗
PubMed1989

Monoclonal antibodies as catalysts and templates for organic chemical reactions.

The motives for mimicking enzymes are twofold: 1) to gain information and deeper understanding which will be relevant to biochemical catalysis, and 2) to extend the chemistry of living organisms in order to be able to invent new reactions--reactions that enzymes either cannot perform, or can perform only with difficulty. It has taken a long time for the bridge of catalytic antibodies to be erected and join organic chemistry and immunology. This is certainly in part because of differences in language, approach, and goals. Increasingly, many researchers in both disciplines are coming closer as a result of the unifying nature of molecular biology. The importance of the basic questions being addressed as well as the tremendous potential for application in diverse areas ensures that the recent initial results will be greatly expanded in the future. Concurrent developments in biology, chemistry, and physical techniques may also have great impact on the use of catalytic antibodies. Chimeric antibodies, where the binding site (variable region or hypervariable region) is derived from a mouse and chosen at will, while the majority of the antibody molecule is human-derived, may allow wide human application. Bifunctional antibodies with two different catalytic reactions taking place in each antibody molecule may be considered. The accurate depiction of the details of antigen-antibody interaction from x-ray crystallography and the prediction of structure will greatly assist those planning experiments. The future of "dial-a-property" catalytic antibodies looks promising and exciting.

Antibodies, Monoclonal↗
PubMed1975

Crystallization and solid-state reaction as a route to asymmetric synthesis from achiral starting materials.

Many molecules which are achiral can crystallize in chiral (enantiomorphic) crystals and, under suitable conditions, crystals of only one chirality may be obtained. The formation of right- or left-handed crystals in excess is equally probable. Lattice-controlled (topochemical) photochemical or thermal solid-state reactions may then afford stable, optically active products. In the presence of the chiral products, achiral reactants may preferentially produce crystals of one chirality, leading to a feedback mechanism for the generation and amplification of optical activity. Amplification of optical activity can also be achieved by solid-state reactions. The optical synthesis of biologically relevant compounds by such routes may be envisaged.

Aminobutyrates↗
PubMedDate not supplied

Characterization of soman-binding antibodies raised against soman analogs.

The production of antibodies against the highly toxic organophosphorus compound soman (GD) has been undertaken. Monoclonal antibodies were raised against two structural analogs of soman which served as haptens for immunization. In these soman analogs the chemically active P-F bond of the soman molecule was substituted by a P-OH group (which is ionized to P-O- under physiological conditions) or a P-H bond, creating compounds which we have named GDOH and GDH, respectively. These soman analogs were linked to carrier proteins through a short linker extending from the pinacolyl group. Monoclonal antibodies were selected according to their ability to bind to the immunizing hapten, and their specificities were determined by competitive inhibition assays. Out of total of 103 anti-GDOH antibodies 22 bound soman, whereas no binding was achieved with 62 anti-GDH antibodies. The two groups of monoclonal antibodies differed also in their structural specificity as demonstrated by different reactivities against a variety of soman analogs and substituted derivatives. These studies indicate that in order to achieve further improvement in anti-soman reactivity with protective potential, other groups (which resemble the OH group) have to be substituted for the F atom in the soman molecule.

Animals↗