Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
Results
Showing 1 to 14 of 14 for “"acyl-enzyme"”.
-
Solid-State 17O NMR as a New Probe to Study Acyl-Enzyme Intermediates
… 17O NMR and quantum mechanical study of three acyl-enzyme intermediates: p-N,N-dimethylaminobenzoyl-chymotrypsin (DAB-CHT), trans¬¬-¬o-methoxycinnamoyl-chymotrypsin (oMC-CHT), and trans-p-methoxycinnamoyl-chymotrypsin (pMC-CHT). At pH 7.8, the three acyl-enzyme intermediates were found to …
-
Halo enol lactone and protio enol lactone inhibitors of alpha-chymotrypsin: Mechanism and stereospecific behavior of inhibition
… showed burst kinetics in the inactivation of the enzyme, which requires a complicated kinetic scheme including partitioning of the first acyl enzyme between the covalent derivatization of the enzyme by the revealed halomethyl ketone reactive group (permanent inactivation) and formation of the …
-
Theoretical and experimental studies of slowly deacylating alpha-chymotrypsin acyl enzymes
The differential deacylation rates for alpha-chymotrypsin beta-phenyl acyl enzymes 13 and 14 have been studied using the techniques of molecular mechanics and molecular dynamics. These studies indicate that the ketone side-chain of slowly deacylating acyl enzyme 13 is hydrogen bonded to the NH of …
-
Insights Into the Dynamic Structure and Inhibitory Mechanism of Plasminogen Activator Inhibitor Type 1
… binding, slowing the formation of the acyl-enzyme complex, and compromising the stabilization of the acyl-enzyme intermediate. The work provides a more comprehensive structural model for the active conformation of PAI-1 and illuminates a new role for the hF/s3A loop sub-domain in the …
-
Halo Enol Lactones as Enzyme-Activated Irreversible Inhibitors of Alpha-Chymotrypsin: I. The Effect of Lactone Substitution Pattern. Ii. Alpha - Amino-Functionalized Lactones
… were prepared to compare their effectiveness as enzyme-activated irreversible (suicide) inhibitors for (alpha)-chymotrypsin with the activities of the corresponding (alpha)-substituted lactones. The 4-phenyl-5(E)-(iodomethylidene) tetrahydro-2-furanone, the …
-
Translocation and proteolysis by the energy-dependent protease ClpAP : coordination of conformational changes and active site chemistry
… deletion of the N-terminal loops stabilizes the acyl-enzyme intermediate. Additionally, size-exclusion chromatography and kinetic studies are used to show that ClpP alone can processively degrade a full-length protein substrate in the absence of ClpA, albeit at a 2000-fold slower rate, and …
-
Halo Enol Lactones as Enzyme-Activated Irreversible Inhibitors of Chymotrypsin: Their Synthesis, Kinetics, and Mechanism of Inactivation (Suicide Substrates)
Halo enol lactones can act as enzyme-activated irreversible inhibitors or suicide substrates for (alpha)-chymotrypsin. Acyl transfer to the active site serine generates a halo methyl ketone that remains tethered in the catalytic site during the lifetime of the acyl enzyme, available for reaction …
-
Characterization of BphD, a C-C bond hydrolase involved in the degradation of polychlorinated biphenyls
… versus HOPDA (λmax = 434 nm), consistent with an enzyme-bound, strained enolate (E:Sse). In studies with BphDLB400 variants, S112A trapped the E:Sse intermediate, implying that Ser112 is required for subsequent tautomerization and hydrolysis. His265 is required for E:Sse formation, as H265A …
-
Trehalose Monomycolate Biosynthesis and Utilization in Mycobacterium tuberculosis
… mycolic acids. The Antigen 85 (Ag85) family of enzymes catalyze the transfer of mycolic acids from a single donor, trehalose monomycolate (TMM), to different acceptors located within the cell wall. Although there are three different pathways in M. tb to produce trehalose, only one, the otsAB …
-
Studies of Lipoic Acid Metabolism in Escherichia Coli
… which is essential for function of several key enzymes. The studies presented in this thesis shed new light into the understanding of how lipoic acid is synthesized and incorporated into proteins in Escherichia coli. In Chapter Two, the nature of the real substrate for lipoic acid synthase was …
-
Enzymology of DHHC-mediated Protein S-Acylation
Protein <italic>S</italic>-acylation is the post-translational modification of proteins with long-chain fatty acids at cysteine residues via a thioester linkage. The most commonly attached lipid is 16-carbon palmitate, thus the process is often called palmitoylation. Unlike other lipid …
-
Lipoic acid assembly on 2-oxoacid dehydrogenases in E.coli
… to provide the substrates of LipA, a SAM radical enzyme that inserts two sulfur atoms into the octanoyl moiety to give the active lipoylated dehydrogenase complexes. We report that the intact pyruvate and 2-oxoglutarate dehydrogenase complexes specifically copurify with both LipB and LipA. …
-
Mechanistic Studies of the Enzymatic Synthesis of Polyesters
… This has a dramatic adverse effect on the enzyme activity as it moves away from the optimum pH 7.0. Buffering the system closer to optimum pH increased the reaction rate. Also, it was found that as the hydrophobicity of the medium, expressed as C logP, increased the reaction rate became …
-
Studies on lipoic acid metabolism
… lipoyl domains (LDs) of the central metabolism enzymes pyruvate dehydrogenase (PDH) and oxoglutarate dehydrogenase (OGDH) is essential for their activation and thus for respiratory growth in the bacterium Escherichia coli and the yeast Saccharomyces cerevisiae. A third lipoic acid-dependent …