[Chemotherapeutic studies of filariasis--synthesis of 5-nitro-2-furyl-vinyl derivatives and their related compounds (author's transl)].
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Biomedical subjects
M Yan
Publications and source records attributed to M Yan.
Chlorinated phenyl azides as photolabeling reagents. Synthesis of an ortho,ortho'-dichlorinated arylazido PCP receptor ligand.
The enhanced photolabeling properties of chlorinated phenyl azides are demonstrated by the synthesis and photolysis of methyl 4-azido-2,3,5,6-tetrachlorobenzoate (3) and methyl 4-azido-3,5-dichlorobenzoate (4). Photolysis of azide 3 in 1 M diethylamine/cyclohexane as the trapping medium gave 34% NH-insertion product. Similar photolysis of azide 4 gave 35% NH insertion product. These results demonstrate that chlorinated phenyl azides are significantly better at undergoing NH insertion than nonhalogenated analogs and suggest that improvement of existing aryl azide-based photolabels might be achieved by introduction of chlorine atoms on either side of the azide group. As an application, 3-azido-2,4-dichloro-10,5-(iminomethano)-10,11-dihydro-5H- dibenzo[a,d]cycloheptene (19), an analog of the potent PCP receptor ligand IDDC (14), was synthesized and its affinity for the PCP receptor was determined to be 6.3 +/- 0.7 microM (IC50 against [3H]MK801).
Affinity Labels↗
N-hydroxysuccinimide ester functionalized perfluorophenyl azides as novel photoactive heterobifunctional cross-linking reagents. The covalent immobilization of biomolecules to polymer surfaces.
The synthesis of N-hydroxysuccinimide (NHS) functionalized perfluorophenyl azides (PFPAs) 2 and 3 is described together with a general method for the covalent modification of polymer surfaces using heterobifunctional, photoactivable cross-linking reagents 1 and 3. The NHS-active ester group becomes covalently attached to the polymer surface via an efficient CH bond insertion reaction of the photogenerated, highly reactive nitrene intermediate derived from the PFPA. The NHS ester is capable of further reaction with a variety of primary amine-containing reagents including biomolecules by way of amide formation. The method is illustrated as follows. Photolysis of polystyrene (PS) and poly-(3-octylthiophene) (P3OT) thin films spin-coated with NHS PFPA ester 1 or 3 gave films 8 or 9, respectively. Each film was then exposed to an aqueous solution of horseradish peroxidase (HRP), giving films 10 or 11, respectively. The amounts of HRP immobilized on PS and P3OT were calculated from enzyme activity assays to be 0.5 +/- 0.1 ng/mm2 for 10a, 1.0 +/- 0.2 ng/mm2 for 11a, 0.2 +/- 0.1 ng/mm2 for 10b, 0.3 +/- 0.1 ng/mm2 for 11b. Using this surface functionalization methodology, biotin-streptavidin-biotin-HRP was constructed on the PS film. The storage stability of HRP thus immobilized through the extended linker, biotin-streptavidin-biotin, was enhanced as compared to that of HRP directly immobilized on the PS surface.
Azides↗
Activation of stress-activated protein kinase by MEKK1 phosphorylation of its activator SEK1.
A kinase distinct from the MEK activator Raf, termed MEK kinase-1 (MEKK), was originally identified by virtue of its homology to kinases involved in yeast mating signal cascades. Like Raf, MEKK is capable of activating MEK in vitro. High-level expression of MEKK in COS-7 cells or using vaccinia virus vectors also activates MEK and MAPK, indicating that MEKK and Raf provide alternative means of activating the MAPK signalling pathway. We have derived NIH3T3 cell sublines that can be induced to express active MEKK. Here we show that induction of MEKK does not result in the activation of MAPK, but instead stimulates the stress-activated protein kinases (SAPKs) which are identical to a Jun amino-terminal kinase. We find that MEKK regulates a new signalling cascade by phosphorylating an SAPK activator, SEK1 which in turn phosphorylates and activates SAPK.
3T3 Cells↗