Inhibition of acyl coenzyme A: cholesterol acyltransferase by 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors

Relatively high concentrations of MK-733 (simvastatin) and MK-803 (lovastatin, mevinolin), which are 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, were found to inhibit acyl coenzyme A: cholesterol acyltransferase (ACAT) of rabbit intestinal microsomes with IC50's of 2.0 x 10(-5) and 3.6 x 10(-5) M, respectively. Dihydroxy acid forms of both MK-733 and MK-803 did not inhibit ACAT activity. A kinetic analysis using a Lineweaver-Burk plot indicated that MK-733 is a competitive inhibitor of ACAT, with a Ki value of 1.2 x 10(-5) M.     

An optimized luciferase bioluminescent assay for coenzyme A

A new bioluminescent method for coenzyme A (CoA) quantification is described. It is based on the enzymatic conversion of dehydroluciferyl-adenylate (L-AMP) into dehydroluciferyl-coenzyme A (L-CoA) by firefly luciferase (E.C. 1.13.12.7) (LUC), which causes a flash of light that can be measured in a luminometer. The method was subjected to optimization using experimental design methodologies to obtain optimum values for the concentrations of L-AMP ([L-AMP]), luciferase ([LUC]), ATP ([ATP]) and luciferin ([LH₂]). This method has a linear response over the range of 0.25–4 μM of CoA, with a limit of detection (LOD) of 0.24 μM and a limit of quantification (LOQ) of 0.80 μM. The assay has a relative standard deviation of about 7%. By coupling this optimized procedure to bioluminescent detection, a sensible and robust method can be obtained for the analysis of CoA.     

Coordination of methyl coenzyme M and coenzyme M at divalent and trivalent nickel cyclams: model studies of methyl coenzyme M reductase active site

Divalent and trivalent nickel complexes of 1,4,8,11-tetraazacyclotetradecane, denoted as cyclam hereafter, coordinated by methyl coenzyme M (MeSCoM(-)) and coenzyme M (HSCoM(-)) have been synthesized in the course our model studies of methyl coenzyme M reductase (MCR). The divalent nickel complexes Ni(cyclam)(RSCoM)(2) (R = Me, H) have two trans-disposed RSCoM(-) ligands at the nickel(II) center as sulfonates, and thus, the nickels have an octahedral coordination. The SCoM(2-) adduct Ni(cyclam)(SCoM) was also synthesized, in which the SCoM(2-) ligand chelates the nickel via the thiolate sulfur and a sulfonate oxygen. The trivalent MeSCoM adduct [Ni(cyclam)(MeSCoM)(2)](OTf) was synthesized by treatment of [Ni(cyclam)(NCCH(3))(2)](OTf)(3) with ((n)Bu(4)N)[MeSCoM]. A similar reaction with ((n)Bu(4)N)[HSCoM] did not afford the corresponding trivalent HSCoM(-) adduct, but rather the divalent nickel complex polymer [-Ni(II)(cyclam)(CoMSSCoM)-](n) was obtained, in which the terminal thiol of HSCoM(-) was oxidized to the disulfide (CoMSSCoM)(2-) by the Ni(III) center.     

Capillary electrophoretic assay of human acetyl‐coenzyme A carboxylase 2

Human acetyl‐coenzyme A carboxylase 2 catalyzes the carboxylation of acetyl coenzyme A to form malonyl coenzyme A, along with the conversion of magnesium‐adenosine triphosphate complex to magnesium‐adenosine diphosphate complex. A simple off‐column capillary electrophoresis assay for human acetyl‐coenzyme A carboxylase 2 was developed based on the separation of magnesium‐adenosine triphosphate complex, magnesium‐adenosine diphosphate complex, acetyl coenzyme A and malonyl coenzyme A with detection by ultraviolet absorption at 256 nm. When Mg²⁺ was absent from the separation buffer, the zones due to magnesium‐adenosine triphosphate complex and magnesium‐adenosine diphosphate complex both split and migrated as two separate peaks. With Mg²⁺ added to the separation buffer, magnesium‐adenosine triphosphate complex and magnesium‐adenosine diphosphate complex produced single peaks, and the reproducibility of peak shape and area improved for human acetyl‐coenzyme A carboxylase 2 assay components. The final separation buffer used was 30.0 mM HEPES, 3.0 mM MgCl₂, 2.5 mM KHCO₃, and 2.5 mM potassium citrate at pH 7.50. The same buffer was used for the enzyme‐catalyzed reaction (off‐column). Inhibition of human acetyl‐coenzyme A carboxylase 2 by CP‐640186, a known inhibitor, was detected using the capillary electrophoresis assay.     

A short,highly efficient synthesis of coenzyme Q(10)

The most efficient synthesis reported to date of ubiquinone (CoQ10) is described. A sequence consisting of six operations is involved which leads to crystalline material in an overall yield of >64%.     

Modeling of coenzyme activity of biotin

Conclusions The nonenzymatic N-carboxylation of the imidazolidinone ring was accomplished by reacting the appropriate K salt with carbon dioxide gas in tert-butyl alcohol medium.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, p. 856, April, 1971.     

In vivo reporter labeling of proteins via metabolic delivery of coenzyme A analogues

We demonstrate site-specific reporter labeling of proteins within live cells. By accessing the coenzyme A (CoA) metabolic pathway with a cell-permeable pantetheine analogue, we deliver CoA-bound reporter molecules for post-translational protein modification in vivo. These methods may be applied to natural product pathway manipulation as well as applications in conventional molecular and cellular biology.     

Synthesis of the bacterial coenzyme methoxatin

A short total synthesis of the bacterial coenzyme methoxatin (1) (4,5-dihydro-4, 5-dioxo-1H-pyrrolo[2,3-f]quinoline-2,7,9-tricarboxylic acid) is described. The route involves the two step conversion of 4-acetamido-2-benzy1oxybenzaldehyde (5b) into methyl 6-acctamido-4-benzyloxyindole-2-carboxylate (7b) (74%), followed by regioselective annulation of the third ring (55%),and debenzylation and oxidation with benzoyl t-butyl nitroxide to give the tricyclic quinone triester (13) (methoxatin triester) (83%).