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A synthesis of acylphosphonic acids and of 1-aminoalkylphosphonic acids: the action of pyruvate dehydrogenase and lactate dehydrogenase on acetylphosphonic acid.

Acylphosphonic acids, R-CO-PO(OH)2, have been synthesized by the steps [formula: see text] of which the last is new and provides a mild method for de-esterifying acylphosphonic acids. Their reductive amination gives a simple way of making 1-aminoalkylphosphonic acids. Acetylphosphonic acid inhibited NAD+ reduction by pyruvate with the pyruvate dehydrogenases from Escherichia coli and Bacillus stearothermophilus. The inhibition was competitive with pyruvate, with Ki of 6 microM for the E. coli enzyme (pyruvate Km 0.5 mM) and one of 0.4 mM of the B. stearothermophilus enzyme (pyruvate Km 0.1 mM). Acetylphosphonate and its monomethyl ester are substates for pig heart lactate dehydrogenase, with Km values of 15 mM and 10 mM respectively (pyruvate Km 0.05 mM) and specificity constants one thousandth that for pyruvate.

Acetaldehyde↗

Comparison of uptake, oxidation and lipid distribution of 17-iodoheptadecanoic acid, 15-(p-iodophenyl)pentadecanoic acid and 15-(p-iodophenyl)-3,3-dimethylpentadecanoic acid in normal canine myocardium.

The kinetics of 17-[123I]iodoheptadecanoic acid (IHDA), 15-(p-[125I]iodophenyl)pentadecanoic acid (pIPPA) and 15-(p-[131I]iodophenyl)-3,3-dimethylpentadecanoic acid (DMIPPA) were investigated in normal canine myocardium. After simultaneous intravenous injection, myocardial biopsy specimens and samples of arterial blood were taken over 80 min. IHDA showed the highest myocardial uptake (995 +/- 248 dpm/mg.mCi versus pIPPA: 785 +/- 197 dpm/mg.mCi, ns) and the largest size of oxidation (74% +/- 4% versus pIPPA: 65% +/- 5%, p < 0.05). Myocardial activity of IHDA decreased with a half-time value of 11.2 min (pIPPA: 13.2 min). Phospholipids were the main lipid fraction into which IHDA was incorporated, whereas pIPPA was predominantly incorporated into triacylglycerols. DMIPPA myocardial activity remained constant during the assay period and instead of being oxidized, DMIPPA was mainly incorporated into triacylglycerols (55% +/- 12%). The myocardium-to-blood ratios of DMIPPA were greater than 10:1. The ratios at peak for IHDA and pIPPA were 4.1:1 and 3.9:1, respectively (both p < 0.0001 versus DMIPPA). In conclusion, differences have been found in the myocardial uptake, oxidation and lipid distribution of IHDA, pIPPA and DMIPPA. DMIPPA is a promising tracer for fatty acid uptake studies with single-photon emission computerized tomography because of its prolonged retention and high myocardium-to-blood ratios.

Animals↗

Nucleic acid enzymology of extremely halophilic bacteria. Gel-filtration and density-gradient-centrifugation studies of the molecular weights of Halobacterium cutirubrum polynucleotide phosphorylase and deoxyribonucleic acid- and ribonucleic acid-dependent ribonucleic acid polymerases.

1. Conditions have been established for the estimation of molecular weights of proteins by analytical gel filtration and sucrose-density-gradient centrifugation in 2.5m-potassium chloride-1m-sodium chloride; Halobacterium cutirubrum polynucleotide phosphorylase, DNA-dependent RNA polymerase and RNA-dependent RNA polymerase have been studied by these methods. 2. The RNA-dependent polymerase has also been studied by density-gradient centrifugation in the absence of salt. 3. All three proteins are of unusually low molecular weight compared with similar enzymes from non-halophilic bacteria.

Acrylamides↗