Correlation of proton release and ultraviolet difference spectra associated with metal binding by transferrin.
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Bicarbonates↗
Biomedical subjects
M H Gelb
Publications and source records attributed to M H Gelb.
Comparison of the antibody response to bee venom phospholipase A2 induced by natural exposure in humans or by immunization in mice.
Two human and twelve murine monoclonal antibodies directed against the main bee venom allergen phospholipase A2 (PLA) were evaluated for their fine specificity of binding to antigen and their ability to inhibit the enzymatic activity of the antigen. Antibodies were induced by natural exposure of beekeepers to bee venom or immunization of mice via different methods. Both human monoclonal antibodies (hmAbs) were previously shown to recognize the native three-dimensional conformation of PLA and are directed against discontinuous epitopes which include lysine residue at position 25 as a contact residue. In contrast, six of the murine monoclonal antibodies (mmAbs) bind to the denatured structure of the protein as determined by enzyme-linked immunosorbent assay. The epitopes recognized are located near the C-terminal end (n = 8), in the centre of the polypeptide (n = 1), near the N-terminal end (n = 1) or include the carbohydrate part (n = 2) of the PLA molecule. The capacity of the antibodies to modify the enzymatic activity was also determined. The hmAbs significantly inhibit the enzyme (70-79%), whereas the mmAbs produced various degrees of inhibition (39-100%). Since the X-ray structure of PLA is known, the epitopes can be visualized in the context of the three-dimensional structure of the antigen. A qualitative correlation was found between the location of epitopes and the inhibition pattern. Strong inhibition was seen with those antibodies that recognize epitopes that lie on the surface of the enzyme that is thought to contact the phospholipid bilayer. The results show that even though both hmAbs and most mmAbs inhibit the enzymatic activity of PLA, the antigen-binding properties of antibodies from different species raised after different routes of immunization differ significantly. Thus, detailed epitope mapping studies using murine antibodies prepared by artificial immunization may have limited value in predicting epitope patterns relevant to an antibody response to allergens in humans naturally exposed to antigen/allergen.
Allergens↗
Design and synthesis of substrate and internal standard conjugates for profiling enzyme activity in the Sanfilippo syndrome by affinity chromatography/electrospray ionization mass spectrometry.
We describe the design and synthesis of substrate and internal standard conjugates for application in profiling enzyme activity of the enzymes alpha-D-2-deoxy-2-N-sulfonamido-glucosamine sulfamidase, alpha-D-2-deoxy-2-N-acetyl-glucosamine hydrolase, acetyl-coenzymeA:alpha-D-2-deoxy-2-amino-glucosamine transferase, and alpha-D-2-deoxy-2-N-acetyl-glucosamine-6-sulfate sulfatase. Deficiency of any one of these enzymes results in a single clinical phenotype known as Sanfilippo syndrome. Such substrates have been proven effective in the confirmation of enzyme deficiency by a combination of affinity chromatography (AC) and electrospray ionization mass spectrometry (ESIMS), which forms the foundation for a new analytical technology (ACESIMS) of general interest and application to clinical and biomedical research.
Acetylgalactosamine↗
Polymer-assisted solution-phase synthesis of 2'-amido-2'-deoxyadenosine derivatives targeted at the NAD(+)-binding sites of parasite enzymes.
A polymer-assisted solution-phase (PASP) synthesis of lead structure analogues ready for biological testing without the demand for chromatographic purification is described. Carboxylic acids are coupled to the Kenner or Ellman safety catch linker, respectively, activated by methylation or cyanomethylation and subsequently transferred to the 2'-amino group of the 2'-amino-2'-deoxyadenosine scaffold (5). The chemoselective attack of weakly nucleophilic amino groups on the N-alkylated N-acyl sulfonamide linker allows for the synthesis of amides 6 in high yields without the need for protection of primary and secondary hydroxyl functions. Thus, the use of 4-sulfamylbenzoylaminomethyl polystyrene is reported for the construction of chemoselective polymer-supported acylating reagents instead of its known use as linker in solid-phase peptide or organic synthesis. This approach is demonstrated to be well suited to obtain 2'-amido-2'-deoxyadenosine derivatives 6 in parallel format. Biological evaluation of all compounds reported revealed no improvement over known lead structures.
Animals↗
Bio-organic chemistry and cytochrome P-450-dependent catalysis.
This review presents current ideas, models and experimental data relating to the precise chemistry that links the transition metal active centre of cytochrome P-450 systems, the unactivated alkane substrate and the triplet atmospheric dioxygen molecule. Aspects considered include the hypervalent transition metal, the reductive activation of the dioxygen molecule by two electrons as an intermediate in the four-equivalent oxidase mechanism, and the details of carbon-hydrogen and carbon-carbon fragmentation. Studies of the microbial camphor 5-exo hydroxylase system are used to exemplify the principles discussed.
Animals↗