Chromatographic detection of the acetohydroxy acid synthase isoenzymes of Escherichia coli K-12.

Two valine-sensitive acetohydroxy acid synthase activities were separable from $\text{Escherichia}\text{coli}$ K-12 cells by virtue of their different affinities for DEAE-cellulose eluted with a KC1 gradient. These activities appeared to be independent from a valine-resistant cryptic component expressed only in $\text{ilvO}$ regulatory mutants. The properties of the first and second activity were coincident to those of extracts of $\text{ilvB}$ and $\text{ilvHI}$ mutants, respectively. These data prove that the $\text{ilvB}$ and $\text{ilvHI}$ gene products exist in the cell as physically distinct acetohydroxy acid synthase isoenzymes.     

The influence of charge on phosphatidic acid bilayer membranes

A complete titration of phosphatidic acid bilayer membranes was possible for the first time by the introduction of a new anaologue, $\text{1,2-}\text{dihexadecyl}\text{-sn-}\text{glycerol-3-phosphoric}$ acid, which has the advantage of a high chemical stability at extreme pH values. The synthesis of this phosphatidic acid is described and the phase transition behaviour in aqueous dispersions is compared with that of three ester phosphatidic acids; $\text{1,2-}\text{dimyristoyl}\text{-sn-}\text{glycerol-3-phosphoric}$ acid, 1,3-dimyristoylglycerol-2-phosphoric acid and $\text{1,2-}\text{dipalmitoyl}\text{-sn-}\text{glycerol-3-phosphoric}$ acid.The phase transition temperatures ($\text{T}{}_{\mathrm{<mtext>t</mtext>}}$) of aqueous phosphatidic acid dispersions at different degrees of dissociation were measured using fluorescence spectroscopy and 90° light scattering. The $\text{T}{}_{\mathrm{<mtext>t</mtext>}}$ values are comparable to the melting points of the solid phosphatidic acids in the fully protonated states, but large differences exist for the charged states.The $\text{T}{}_{\mathrm{<mtext>t</mtext>}}$ vs. pH diagrams of the four phosphatidic acids are quite similar and of a characteristic shape. Increasing ionisation results in a maximum value for the transition temperatures at pH 3.5 ($\text{p}\text{K}{}_1$). The regions between the first and the second $\text{p}\text{K}$ of the phosphatidic acids are characterised by only small variations in the transition temperatures (extended plateau) in spite of the large changes occurring in the surface charge of the membranes. The slope of the plateau is very shallow with increasing ionisation. A further decrease in the H⁺ concentration results in an abrupt change of the transition temperature. The slope of the $\text{T}{}_{\mathrm{<mtext>t</mtext>}}$ vs. pH diagram beyond $\text{p}\text{K}{}_2$ becomes very steep. This is the     

Effect of E. coli endotoxin on the structure-function of fatty acid synthetase lipoprotein

The lipoprotein structure of the fatty acid synthetase complex from Ceratitis capitata has been used as a model to $\text{val}\text{i}$ date the claim that phospholipids from membranes assume a $\text{signif}\text{i}$ cant role in the cell-endotoxin interactions. The enzyme-complex was exposed to a ¹⁴C-lipopolysaccharide preparation and the $\text{inte}\text{r}$ action was followed by a) circular dichroism spectra, b) enzyme activity and c) gel filtration chromatography. It should be $\text{emph}\text{a}$ sized that the E. coli endotoxin modifies all these properties of the enzyme complex and that a model involving phospholipids and phase transitions has been proposed to account for these $\text{intera}\text{c}$ tions.     

Occurrence of cis-7-tetradecenoic acid in the envelope phospholipids of Escherichia coli K12

We have isolated a tetradecenoic acid from $\text{E}\text{.}\text{coli}$ and have identified this new acid as $\text{cis}$-7-tetradecenoic by its ¹³C nuclear magnetic resonance spectrum. This identification was confirmed by conventional structural studies. The acid is a component of the phospholipids of $\text{E}\text{.}\text{coli}$ and comprises about 15% of the total phospholipid unsaturated fatty acid.     

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 $\text{E.}\text{coli}$.     

Inhibition of cyclopropane fatty acid synthase by sinefungin and A9145C

Sinefungin and A9145C, antifungal antibiotic analogs of S-adeno-sylmethionine isolated from $\text{Streptomyces}\text{,}\text{griseolus}$, have been found to be very effective $\text{in}\text{,}\text{vitro}$ inhibitors of cyclopropane fatty acid synthase from $\text{Lactobacillus}\text{,}\text{plantarum}$. Both compounds exhibit linear competitive inhibition with a K_i for Sinefungin of 220 nM and a K_i for A9145C of 11 nM.     

Amino acid sequence of Desulfovibrio gigas ferredoxin: revisions

Reexamination of the amino acid sequence of $\text{Desulfovibrio}$$\text{gigas}$ ferredoxin revealed that the sequence published in 1971 should be revised. This sequence was determined using automatic protein sequencer in liquid phase and in solid phase. Peptides derived from tryptic hydrolysis, $\text{Staphylococcus}$$\text{aureus}$ protease hydrolysis, cyanogen bromide cleavage were used to construct the total sequence. This ferredoxin contains 6 cysteines per minimum molecular weight of 6,400. 4 cysteines are linked to a (4 Fe-4 S) cluster and the two others possibly participate in a disulfide bridge.     

Lack of involvement of lipoic acid in membrane-associated energy transduction in Escherichia coli.

Oxidative phosphorylation, active transport of proline, aerobic- and ATP-driven proton translocation and transhydrogenation of NADP⁺ by NADH, occurred in lipoic acid-deficient cells or vesicles of a lipoic acid auxotroph of $\text{E. coli}$, W1485 lip 2. Addition of lipoic acid had little effect on these processes. Tributyltin chloride, which has been proposed to inhibit oxidative phosphorylation by reaction with lipoic acid (Cain $\text{et al.}$, Biochem. J. (1977) $\text{166}$, 593), was an effective inhibitor of aerobic and ATP-dependent proton translocation and transhydrogenation in lipoic acid-deficient vesicles from this organism. Our results do not support the proposal of Partis $\text{et al.}$ (FEBS Lett. (1977) $\text{75}$, 47) that lipoic acid is involved in the energy transducing processes associated with the membrane of $\text{E. coli}$.     

Antibacterial properties of bile acid oxazoline compounds

Chenooxazoline³ (50–100 μM) inhibited (>50%) both 7α and 7β-dehydroxylase activities in whole cells and cell extracts of $\text{Eubacterium}$ sp. V.P.I. 12708. Chenooxazoline (>50 μM) and methylchenooxazoline (>25 μM) but not lithooxazoline (≤100 μM) inhibited growing cultures of $\text{Eubacterium}$ sp. V.P.I. 12708. Chenooxazoline (100 μM) also inhibited the growth of certain members of the genera $\text{Eubacterium}$, $\text{Clostridium}$, $\text{Bacteroides}$ and $\text{Staphylococcus}$ but not $\text{Pseudomonas}$, $\text{Escherichia}$, $\text{Salmonella}$ or the eucaryotic microorganism, $\text{Saccharomyces cerevisiae}$ (_< 400 μM).     

A rapid isotope dilution method for analysis of indole-3-acetic acid and indoleacetyl aspartic acid from small amounts of plant tissue

A method is described for analysis of indole-3-acetic acid and indoleacetyl aspartic acid in plant tissue. Methanolic extracts are purified on two small columns prior to HPLC using an electrochemical detector. $\text{In}$,$\text{vivo}$ amounts are calculated by isotope-dilution analysis. The method requires only 1 g of tissue, results in relative high recoveries, and is sensitive to the 20 pmol range or below. Typical results using light-grown $\text{Pisum}$,$\text{sativum}$ cv. Little Marvel tissue are given. This report is the first determination of the natural level of the aspartate derivative in growing plant tissues.     

Biosynthesis of glycerol teichoic acid in Bacillus cereus: formation of linkage unit disaccharide on a lipid intermediate

A tunicamycin-like antibiotic 24010 at a concentration of 1 μg/ml selectively inhibited the $\text{in vivo}$ synthesis of glycerol teichoic acid of cell walls in $\text{Bacillus cereus}$ AHU 1030. Incubation of membranes of this strain with $\text{N}$-acetylglucosaminyl pyrophosphorylundecaprenol and UDP-$\text{N}$-acetylmannosamine led to formation of a glycolipid having a saccharide moiety identical with the cell wall teichoic acid linkage unit, $\text{N}$-acetylmannosaminylβ(1→4)-$\text{N}$-acetylglucosamine. The membranes also catalyzed transfer of glycerol phosphate units from CDP-glycerol to this disaccharide-linked lipid. Thus the biosynthesis of the cell wall glycerol teichoic acid in this strain seems to involve the disaccharide-linked lipid as an intermediate.     

Amino acid transport by the helicoidal colon of the new-born pig

The proximal colon of the new-born pig maintains a stable short-circuit current which is partly dependent upon the presence of methionine. This interaction between methionine and short circuit current shows Michaelis- Menten knetics with a $\text{K}{}_{\mathrm{<mtext>m</mtext>}}$ of 0.24 mM and a $\text{V}$ of 27 μA·cm^?2. The net flux of methionine to the serosal surface of proximal colons also shows a hyperbolic relation to the external concentration of methionine ($\text{K}{}_{\mathrm{<mtext>m</mtext>}}\text{0.38}\text{mM}$; $\text{V 10.4}\text{nmol}\text{·}\text{cm}{}^{\mathrm{?2}}\text{·}\text{min}{}^{\mathrm{?1}}$). The proximal colon concentrates methionine within its epithelium giving a mucosal to medium ratio of $\text{11.2 ± 1.9}$ (90 min incubation in 1 mM methionine).The ability of the colon to transport methionine across and concentrate methionine within its mucosa is maintained for at least 24 h after birth. Colonic transport of amino acids could be physiologically important in the pig, where the immediate post-natal transfer of immune globulins has been shown to cause a temporary inhibition of normal intestinal function.     

Coenzyme A: fatty acid synthetase apoenzyme 4'-phosphopantetheine transferase in yeast

A mixture of two pantetheine-free mutant fatty acid synthetases was dissociated and recombined $\text{in}$$\text{vitro}$ to form a hybrid apoenzyme complex. $\text{In}$$\text{vivo}$ the corresponding $\text{Saccharomyces}$$\text{cerevisiae}$$\text{fas}$-mutants exhibit interallelic complementation when crossed with each other and the enzyme synthesized in the resulting diploid contains pantetheine and exhibits overall fatty acid synthetase activity. Accordingly, the hybrid apoenzyme formed $\text{in}$$\text{vitro}$ could be activated to holo-fatty acid synthetase when incubated with coenzyme A and a partially purified yeast cell extract. The enzyme coenzyme A: fatty acid synthetase apoenzyme 4′-phosphopantetheine transferase has thus been identified in yeast. Further studies on the mechanism of fatty acid synthetase holoenzyme formation will now be possible.     

Amino acid sequence of the heme a subunit of bovine heart cytochrome oxidase and sequence homology with hemoglobin.

The amino acid sequence of the 11.6 K dalton heme $\text{a}$ subunit of bovine heart cytochrome oxidase has been completed and is presented here. The sequence investigation has established the positions in the protein of all the possible heme ligands, namely cysteine, methionine, histidine and lysine residues. However, the isolation conditions may have caused the heme $\text{a}$ to migrate from its original site or the heme is caged by peptides as pointed out in Reference 6. The sequence of the heme $\text{a}$ subunit and the β-chain of hemoglobin shows homology. It is possible that these two proteins have arisen from a common ancestor in the distant past.     

Determination of vanilmandelic acid in pig urine and chicken feces by gas-liquid chromatography

A gas chromatography method for the determination of free and bound vanilmandelic acid (VMA) in pig urine and chicken feces has been developed. The method consisted of extraction of the free or bound acids by ethyl acetate under acidic conditions. The ethyl acetate extracts were dried under nitrogen, followed by complete silylation of the phenolic and carboxylic acid groups with BSA (N,O)-bis (trimethylsilyl) acetamid. The solution was distilled at 180°C in a sealed glass tube after which the sample was injected on a stainless steel column (6 ft × .125 in. o.d.) containing 4% SE-30 on $\text{80}\text{100}$ mesh chromosorb GHP. The recovery of the urinary VMA was 82%, and the fecal VMA was 84% through the outlined procedures. Pigs ranging in age from 8 to 12 weeks were found to excrete $\text{2–8 mg urinary VMA}\text{24 hr}$ with no significant difference between the free and bound. Commercial laying hens excreted bound VMA in a range of $\text{1–5 mg}\text{24 hr}$ with a $\text{F}\text{B}$ ratio of 1:3.     

Inhibition of porphobilinogen synthase by heme and an enol-ether amino acid

The enol-ether amino acid, L-2-amino-4-methoxy-$\text{trans}$-butenoic acid (AMTB) is an inhibitor of porphobilinogen synthase (PBG synthase) when added prior to the addition of the substrate δ-aminolevulinic acid. The inhibition of PBG synthase by several stereoisomers and analogues of AMTB was investigated to determine those structural features of AMTB which may be necessary for inhibition. The D-$\text{trans}$ isomer was also an inhibitor after preincubation, whereas the L-$\text{cis}$ isomer inhibited with or without preincubation. The amino acid analogues, DL-vinylglycine, DL-2-aminobutanoic acid, the reduced form of L-2-amino-4-methoxy-$\text{trans}$-3-butenoic acid, L-2-amino-4-(2-aminoethoxy)-$\text{trans}$-3-butenoic acid and its reduced congener did not inhibit PBG synthase even with preincubation. This structure activity relationship indicates that the $\text{trans}$ double bond and methoxy moiety of L-2-amino-4-methoxy-$\text{trans}$-3-butenoic acid are probably required for inhibition.Heme, when preincubated with PBG synthase, was an inactivator of the enzyme. However, when both L-2-amino-4-methoxy-$\text{trans}$-3-butenoic acid and heme were simulatneously preincubated with PBG synthase, inactivation of the enzyme was greater than with either compound separately. The possibility of multiple catalytic sites was suggested by the use of multiple inhibition kinetics in the presence of heme and L-2-amino-4-methoxy-$\text{trans}$-3-butenoic acid.     

Synthesis of a fluorescent boronic acid which reversibly binds to cell walls and a diboronic acid which agglutinates erythrocytes

N-(5-dimethylamino-1-napthalene sulfonyl)-3-aminobenzene boronic acid (Dns-PBA) and N,N′-$\text{bis}$-3(dihydroxylborylbenzene)adipamide (Bis-PBA) were synthesized. The former is found to reversibly associate with $\text{Bacillus}$$\text{subtilis}$, apparently through boronate diester linkages with carbohydrates on the cell surface. The latter displays the lectin-like property of agglutinating red blood cells.     

Biosynthesis of -linolenic acid by disrupted spinach chloroplasts

A disrupted spinach chloroplast preparation readily synthesized $\text{[}{}^{14}\text{C]α-linolenate}$ from [2-¹⁴C]acetate under anaerobic conditions. It can be shown by degradation data that [¹⁴C]oleate is not a precursor of [¹⁴C]linolenate and that $\text{cis}$ 7,10,13-hexadecatrienoic acid is the probable immediate precursor of the [¹⁴C]linolenate.     

Metabolism of mevalonic acid to long chain fatty alcohols in an insect

A mixture of long chain fatty alcohols (LCFA) with chain lengths of 24 to 30 carbon atoms, as free and esterified components, have been isolated from the aphid, $\text{Schizaphis}\text{graminum}$. Both radiolabelled mevalonic acid and palmitic acid served as effective precursors in the synthesis of LCFA. This is the first time that the $\text{trans}$-methylglutaconate shunt has been shown to be operational for fatty alcohol synthesis and to occur in a lower-evolved animal.     

Metabolism and uptake of L-pipecolic acid by brain and heart

Metabolism and uptake of $\text{L}$-[1-¹⁴C]pipecolate was studied in the rat through tail vein injection at low (30 μg/kg) and high (30 mg/kg) doses. No radioactive compound other than $\text{L}$-pipecolate was detected in the brain or heart samples 0.5 to 60 min after injection. The contents of $\text{L}$-pipecolate in the brain dropped rapidly to reach a plateau value 2 min after injection both in the low and high dose experiments (from 0.06 to 0.05 and from 86 to 55 nmole/g brain, respectively). Similar results were observed for the heart except that the heart had $\text{L}$-pipecolate contents 2–3 fold higher than the brain at every time interval. The influx of $\text{L}$-pipecolate to the brain, as measured by the plasma/brain ratio of its contents, was 3 fold lower than the heart at each sampling point throughout the course of measurement for both dosages. The influx of $\text{L}$-pipecolate from the plasma to the heart reached an equilibrium, i.e., plasma/heart = 1, 60 min after injection for both dosages; the plasma to brain ratio was 3 at 60 min. These results indicate that there is a blood-brain transport barrier for $\text{L}$-pipecolate in the rat, which may account for the differences in neuronal effects of $\text{L}$-pipecolate when administered intracerebrally or intraperitoneally.