Mark R. Harpel

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An improved anion-exchange chromatographic method for determining the carboxylation/oxygenation specificity (tau) of ribulose 1,5-bisphosphate carboxylase/oxygenase is presented. This assay, which entails radiometric detection of [1-3H]ribulose-bisphosphate turnover products separated on MonoQ anion-exchange resin, is more convenient, less error-prone, and(More)
BACKGROUND AND PURPOSE Recently identified antagonists of the urotensin-II (U-II) receptor (UT) are of limited utility for investigating the (patho)physiological role of U-II due to poor potency and limited selectivity and/or intrinsic activity. EXPERIMENTAL APPROACH The pharmacological properties of two novel UT antagonists, GSK1440115 and GSK1562590,(More)
Gentisate 1,2-dioxygenase catalyzes the oxygenolytic ring cleavage of gentisate (2,5-dihydroxybenzoate) between carbons 1 and 2 to form maleylpyruvate. The essential active site Fe2+ of the enzyme binds NO to yield an EPR-active (S = 3/2) complex. Hyperfine broadening from 17O (I = 5/2) is observed in the spectrum of the enzyme-nitrosyl complex prepared in(More)
Antithrombotic agents that are inhibitors of factor XIa (FXIa) have the potential to demonstrate robust efficacy with a low bleeding risk profile. Herein, we describe a series of tetrahydroquinoline (THQ) derivatives as FXIa inhibitors. Compound 1 was identified as a potent and selective tool compound for proof of concept studies. It exhibited excellent(More)
The CO2/O2 specificity factor of ribulose-bisphosphate carboxylase/oxygenase partially determines the efficiency of photosynthetic carbon assimilation. Heretofore, engineered alterations of the enzyme have only decreased the selectivity for CO2 utilization. We show that alanyl replacement of active-site Ser-368 of the Rhodospirillum rubrum carboxylase(More)
Previous studies have shown that glucagon-like peptide-1 (GLP-1) provides cardiovascular benefits independent of its role on peripheral glycemic control. However, the precise mechanism(s) by which GLP-1 treatment renders cardioprotection during myocardial ischemia remain unresolved. Here we examined the role for GLP-1 treatment on glucose and fatty acid(More)
Site-directed mutagenesis has implicated active-site Lys329 of Rhodospirillum rubrum ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) in promoting the reaction of CO2 with the 2,3-enediol of ribulose bisphosphate and in stabilizing carboxylation intermediates [Hartman, F. C., & Lee, E. H. (1989) J. Biol. Chem. 264, 11784-11789; Lorimer, G. H.,(More)