Cycloheximide inhibition of insulin control of liver glycogen synthase b into a conversion.

Cycloheximide given to insulin-treated alloxan diabetic rats results in the inhibition of insulin-induced liver glycogen synthase $\text{b}\text{into}\text{a}$ conversion without affecting the level of synthase $\text{b}$. The effect of cycloheximide, believed to elevate cAMP in liver of normal rats, is independent of cAMP levels of the insulin-treated diabetic rat. The inhibition of insulin-mediated synthase $\text{b}$ to $\text{a}$ conversion by cycloheximide does not appear to be the result of a cycloheximide-induced cAMP-dependent phosphorylation of synthase $\text{a}$ to $\text{b}$ and suggests that insulin control of synthase $\text{b}$ and $\text{a}$ interconversions is dependent upon cycloheximide-sensitive protein synthesis.     

Effects of adrenal steroid activator protein on the conversion of various 20- and 22-hydroxycholesterols to pregnenolone by adrenal mitochondrial enzymes

A heat-stable protein activator from bovine adrenal cortex mitochondria stimulates the conversion of cholesterol to pregnenolone in crude extracts of adrenal mitochondria, and resembles in some of its properties, the sterol carrier protein of liver (Kan $\text{et}\text{al}$. $\text{Biochem}$. $\text{Biophys}$. $\text{Res}$. $\text{Commun}$. $\text{48}$, 423–429, 1972). We have shown that activator preparations also stimulate highly purified adrenal enzyme preparations comprising four components: cytochrome P-450 specific for side chain cleavage, adrenodoxin, adrenodoxin reductase, and an NADPH-generating system. Furthermore, this activator stimulates the conversion not only of cholesterol, but also of (20S)-20-hydroxycholesterol, (22$\text{R}$)-22-hydroxycholesterol, and (20$\text{R}$, 22$\text{R}$)-20,22-dihydroxycholesterol to pregnenolone. Our findings provide additional evidence that the steroid-activator complexes are the substrates for the side chain cleavage enzyme and that the monohydroxy and dihydroxycholesterols are true intermediates in the conversion of cholesterol to pregnenolone by bovine adrenal cortex mitochondria.     

A formal synthesis of 18-hydroxyestrone

A formal synthesis of $\text{dl}$-18-hydroxyestrone has been achieved by the preparation of $\text{dl}$-3-methanesulfonyloxy-13β,17β-dicarboxy-18--norestra-1,3,5(10)-triene anhydride, the dextrorotatory enantiomer of which is an intermediate in Barton's conversion of $\text{d}$-estrone to $\text{d}$-1β-hydroxyestrone (KC-6A).     

Chorismate mutase-catalyzed reaction of (±)-chorismic acid

Chorismate mutase-prephenate dehydrogenase from $\text{E.}\text{coli}$ and chorismate mutase from $\text{S.}\text{aureofaciens}$ do not catalyze the conversion of (+)-chorismate (unnatural enantiomer) to prephenate. (+)-Chorismate does not inhibit the isomerization of (?)-chorismate to prephenate with chorismate mutaseprephenate dehydrogenase from $\text{E.}\text{coli}$.     

Trilostane,an orally active inhibitor of steroid biosynthesis

Trilostane is a competitive inhibitor of 3β-hydroxysteroid dehydrogenase. $\text{In}$$\text{vitro}$, the drug inhibits conversion of pregnenolone to progesterone but does not alter conversion of cholesterol to pregnenolone nor progesterone to corticoid hormones. When given orally to rats, trilostane inhibits corticosterone and aldosterone production and elevates circulating levels of pregnenolone at doses lower than those that produce adrenal hypertrophy or inhibit gonadal steroidogenesis.     

Leukotriene A: stereochemistry and enzymatic conversion to leukotriene B

Leukotriene A was assigned the structure 5(S)-$\text{trans}$-5,6-oxido-7,9-$\text{trans}\text{-11,14-}\text{cis}$-eicosatetraenoic acid by the enzymatic conversion of a synthetic product of known stereochemistry into the naturally occurring isomer of 5(S),12(R)-dihydroxy-6,8,10,14-eicosatetraenoic acid in human polymorphonuclear leukocytes.     

The accumulation of glycinamide ribotide by ade3 and ade8 mutants of Saccharomyces cerevisiae

The purine intermediate GAR is present in cell free extracts of $\text{ade3}$ and $\text{ade8}$ mutants of yeast. It is also detectable following acid hydrolysis of extracts of $\text{ade6}$ and $\text{ade7}$ which accumulate FGAR and FGAM respectively. GAR accumulation is repressed by growing cells in high levels of adenine. Neither $\text{ade4}$ nor $\text{ade5}$ accumulate GAR and both prevent accumulation of GAR in $\text{ade3}$ and $\text{ade8}$ and FGAR in $\text{ade6}$. Since $\text{ade3}$ is known to be defective in folate metabolism these results indicate that $\text{ade8}$ is blocked in the conversion of GAR→FGAR.     

Biosynthesis and excretion of meta and para tyramine in the rat

$\text{Meta}$ and $\text{para}$ tyramine, after conversion to their bis dansyl derivatives, have been identified and quantitated by mass spectrometry in rat urine. The daily $\text{para}$ to $\text{meta}$ excretion ratio of 1.69 ± 0.10 is quite constant which suggests an endogenous origin for these amines. Following intraperitoneal injection of [¹⁴C] labelled dopa and dopamine more $\text{meta}$ than $\text{para}$ tyramine is excreted; after i.p. injection of $\text{para}$ tyrosine only small amounts of $\text{para}$ tyramine could be identified. This implies that some $\text{para}$ tyramine is synthesised by a route other than dehydroxylation or decarboxylation.     

Phosphorylation and anti-leishmanial activity of formycin B

The inosine analog formycin B (1–10 μM) inhibited the $\text{in vitro}$ growth of $\text{Leishmania}$ promastigotes and amastigotes. When administered to Syrian hamsters infected with $\text{Leishmania}\text{donovani}$, formycin B (10 mg qd × 5) decreased by greater than 90% the number of liver amastigotes, with a concomitant reduction in hepatosplenomegaly. Both extracts and intact cells of $\text{Leishmania}$, unlike mammalian cells, effectively phosphorylated formycin B. The resulting formycin B monophosphate inhibited dose dependently the conversion of IMP to adenylosuccinate in parasite extracts. This effect may be related to the potent anti-leishmanial activity of formycin B.     

Biosynthesis of tylosin: Oxidations of 5-O-mycaminosylprtylonolide at C-20 and C-23 with a cell-free extract from Streptomycesfradiae

The enzymatic conversion of various tylosin precursors was carried out using a cell-free system of the tylosin producer $\text{Streptomyces}\text{fradiae}$ to determine the order and intermediates of oxidations of the 16-membered branched lactone ring at C-20 and C-23 in the biosynthesis of tylosin. It was found that the order of the oxidation of the lactone is: (1) hydroxylation of 5-$\text{O}$-mycaminosylprotylonolide at C-20, (2) oxidation of C-20 hydroxymethyl to formyl, (3) hydroxylation at C-23 to give 5-$\text{O}$-mycaminosyltylonolide. The formation of 23-hydroxy-5-$\text{O}$-mycaminosylprotylonolide from 5-$\text{O}$-mycaminosylprotylonolide was not observed.     

The hydroxylation of P-cresol and its conversion to P-hydroxybenzaldehyde in Pseudomonas putida.

Cell extracts of $\text{Pseudomonas putida}$ catalyze the conversion of $\text{p}$-cresol to $\text{p}$-hydroxybenzylalcohol when phenazine methosulfate, an electron acceptor, is added. The reaction will proceed under anaerobic conditions and a mechanism involving dehydrogenation to a heteroquinone followed by hydration is proposed. This contrasts with the known attack on methyl groups by mono-oxygenases. The same requirements are found for the alcohol dehydrogenase and the major product from reaction mixtures is the aldehyde. Of the compounds tested as substrates only those with the appropriate groups in the $\text{para}$ orientation were attacked.     

Synthesis and accumulation of polyamines in rat liver regenerating after treatment with carbon tetrachloride

A single intraperitoneal injection of carbon tetrachloride into rats resulted within 12 hours in a marked accumulation of putrescine in liver with a concomitant decrease in the concentration of spermidine. The accumulation of putrescine apparently was partly due to an immense stimulation of ornithine decarboxylase activity occurring at the same time. However, in addition it was found that during the maximal accumulation of putrescine there was a marked incorporation of radioactivity from labelled spermidine to liver putrescine $\text{in vivo}$. The conversion of spermidine to liver putrescine was hardly detectable in control animals. Besides the treatment with carbon tetrachloride, increased conversion of radioactive spermidine to liver putrescine $\text{in vivo}$ also occurred after treatment with growth hormone, after partial hepatectomy and after treatment with thioacetamide, $\text{i. e.}$ under circumstances characterized by a stimulation of ornithine decarboxylase activity and an increased accumulation of putrescine.     

11-Trans leukotriene C: A naturally occurring slow reacting substance

A slow reacting substance, produced by murine mastocytoma cells, has been shown to have the structure 5(S)-hydroxy-6(R)-$\text{S}$-glutathionyl-7,9,11-$\text{trans}\text{-14-}\text{cis}\text{-eicosatetraenoic acid (11-}\text{trans}$ leukotriene C, previously referred to as leukotriene C-2) by ultraviolet spectroscopy, amino acid analyses, lipoxygenase conversion and comparisions with a synthetic compound of known structure and stereochemistry.     

Absence of ferric enterobactin receptor modification activity in mutants of Escherichia coli K-12 lacking protein a.

The modification activity for the ferric enterobactin receptor in the Triton X-100 solubilized outer membrane of $\text{Escherichia}\text{coli}$ K-12 was adsorbed to a column of $\text{p}$-aminobenzamidine-//-sepharose and eluted with free benzamidine. Recombination of the dialyzed eluate with the filtrate from the column reinstituted conversion of the receptor from 81K to 81K¹, the latter exhibiting an apparent molecular weight of 74,000 daltons in sodium dodecyl sulfate polyacrylamide gel analysis. The eluate from the $\text{p}$-aminobenzamidine column was shown to contain a component, coincident on gels with both protein and modification activity, which by mutational and other analyses appears to be identical with protein $\text{a}$ of the outer membrane.     

Chloroplast culture IX chlorophyll(ide) a biosynthesis invitro at rates higher than inMvivo

Chlorophyll $\text{a}$ is the plant pigment which in nature catalyzes the conversion of solar energy into chemical energy. By pretreating etiolated cucumber cotyledons with kinetin and gibberellic acid in the dark, it was observed that the plastids which were isolated from such tissues, and incubated in a cofactor-fortified medium, under a repetitive light-dark regime, were capable of synthesizing chlorophyll(ide) $\text{a}$ from exogenous δ-aminolevulinic acid at a rate about twice as high as the highest rates observable in greening tissues $\text{in}\text{vivo}$.     

Triplet states in photosynthesis

A comparison of zero field splitting (ZFS) and spin polarization of triplet spectra of bacteriochlorophyll $\text{a in vitro}$ and $\text{in vivo}$ provides support for the special pair model of photoreactive chlorophyll in photosynthetic bacteria. Spin polarization of the triplet spectra is a new and unique probe of primary events in the light conversion act in photosynthesis.     

In vitro activation of leukocyte glycogen synthetase

The activity of leukocyte glycogen synthetase in a freshly prepared homogenate is almost completely in the $\text{b}$ form. Incubation of the homogenate at 30°C caused a time dependent increase in the activity measured in the absence of G-6-P ($\text{b}$ to $\text{a}$ conversion). The K_a for G-6-P decreased from 0.7 to 0.01 mM. Freezing of the homogenate resulted in a complete loss of the capacity for activation. These results demonstrate that glycogen synthetase from leukocytes of normal human subjects can be converted $\text{in vitro}$ to a form, which is almost independent of G-6-P for activity.     

An A-nor-3-thia-5beta-pregnane.

The conversion of a 5β-pregnan-3-one into a 3-thia-A-nor-pregnane is described. The single epimer, characterized as the 5β-isomer by nmr spectroscopy, was obtained.A previous report [1] from this laboratory described the synthesis of the epimeric 3-oxa-A-norpregnan-20-ones $\text{1}$ and $\text{2}$ from A-norprogesterone. Recently, the total synthesis of the related A-nor-3-thiaestra-1,-5(10)-diene derivative $\text{3}$ has been described [2]. Continuing interest [3] in A-ring-modified steroids as probes of drug-receptor interactions prompts this report of the preparation of the 3-thia-5β-A-norpregnan-20-one $\text{4}$.     

Myosin light chain phosphorylation and phosphorylase A activity in rat extensor digitorum longus muscle.

Phosphorylation of the 18,500 dalton light chain of myosin and conversion of phosphorylase $\text{b}$ to $\text{a}$ were examined in relation to isometric tension development. Following a l sec tetanic contraction, light chain phosphate content increased from a pre-tetanic value of 0.10 to 0.75 mol phosphate/mol at 7 sec; phosphorylase $\text{a}$ activity (ratio of activity $\text{?5′AMP}\text{+5′AMP}$) increased from 0.03 to 0.42 at 4 sec and decreased to control values within 20 sec. Light chain phosphate content, however, declined much more slowly and correlated to post-tetanic potentiation of peak twitch tension. Our results suggest light chain phosphorylation is not obligatory for contraction but may play a role in post-tetanic potentiation.     

Interferon inhibition of hexose monophosphate shunt activity as the mechanism of blocking differentiation of a preadipose cell line

Mouse L cell interferon (IFN $\text{α}\text{β}$) inhibited the differentiation of mouse 3T3-Li fibroblasts into adipocytes. IFN $\text{α}\text{β}$ also inhibited hexose monophosphate shunt (HMP) activity in these cells. HMP activity is required for the reducing power necessary for the conversion of 3T3-Li fibroblasts to adipocytes. Both IFN blockage of differentiation and HMP activity were reversed by the reducing agent 2-mercaptoethanol, probably through interaction with membrane receptors and not through direct inactivation of IFN. Several non-antiviral effects of IFN $\text{α}\text{β}$ on cellular function, including differentiation and immunoregulation, may be mediated at the biochemical level through blockage of HMP activity.