Browsing by Subject "Mechanism of action"
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Item Chemical biology studies of neuroregenerative small molecules using Caenorhabditis elegans(2015-05) Zlotkowski, Katherine Hannah; Liu, Hung-wen, 1952-; Siegel, Dionicio R.; Pierce-Shimomura, Jon; Keatinge-Clay, Adrian; Dong, GuangbinThe debilitating effects of spinal cord injury can be attributed to a lack of regeneration in the central nervous system. Identification of growth-promoting pathways, particularly ones that can be controlled by small molecules, could provide significant advancements in regenerative science and lead to potential treatments for spinal cord injury. The biological investigations of neuroregenerative small molecules, specifically the natural products clovanemagnolol and vinaxanthone, have been expanded to a whole organism context using the nematode Caenorhabditis elegans (C. elegans) as a tool for these studies. A straightforward assay using C. elegans was developed to screen for compounds that promote neuronal outgrowth in vivo. This outgrowth assay was then used to guide the design of chemically edited analogs of clovanemagnolol that maintained biological activity while possessing structures amenable to further modification for mechanism of action studies. Pull-down experiments using affinity reagents synthesized from a neuroactive structural derivative, clovanebisphenol, and the C. elegans proteome combined with mass spectrometry-based protein identification and genetic recapitulation using mutant C. elegans identified the putative protein target of the small molecule as a kinesin light chain, KLC-1. Furthermore, the small molecule-promoted regeneration of injured neurons in vivo was studied using laser microsurgery to cut specific axons in C. elegans followed by treatment with a library of analogs of the growth-promoting natural product vinaxanthone. Enhanced axonal regeneration was observed following small molecule treatment and the results were used to determine the structure-activity relationship of vinaxanthone, which may guide future development of potential drug candidates for the treatment of spinal cord injury.Item Enzymology of metallo-B-lactamases(Texas Tech University, 1996-08) Glover, Bradley P.Pathogenic bacteria become resistant to penidlhns and cephalosporins through acquisition of a gene encoding the enzyme p -lactamase. (Livermore, 1991) Four classes distinguish P-lactamases as either active site serine hydrolases (class A, C and D) or zinc containmg hydrolases (class B). The class C enzyme is further distmguished from the others by being membrane bound. These bacterial enzymes catalyze the hydrolysis of the p-lactam amide group of their substrates. The class A enzyme has been studied extensively with respect to its structure, hydrolysis mechanism and inhibition. Class A enzymes proceed through an acyl-enzyme intermediate involving an active site serine residue (Fisher et al., 1980). Many substrate and transition state analogs have exhibited inhibitory effects on the class A enzyme and are used medicinally as antibiotic supplements (Wainwright, 1990). Until recently, the class B P-lactamases did not demand such study as their class A counterparts. Now, more and more clinical cases of carbapenem resistant bacteria containing the class B, zinc-requiring enzyme has caused some concern (Payne, 1993). The increased occurrence of noxious gram-positive resistant bacteria has sparked a renewed investigation into p-lactamase enzymology.