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Isolated etioplasts from 8-day-old dark-grown pea seedlings incorporated [1-14C]acetate into lipid at a relatively low rate. Plastids from seedlings that had been illuminated for at least 2 hr showed an enhanced incorporation provided the plastids were illuminated during incubation with the labeled acetate. Dark incubation or the addition of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) decreased the acetate-incorporating activity of the developing chloroplasts to the level observed with etioplasts. Light had a marked effect on the type of fatty acid into which acetate was incorporated by the developing chloroplasts. Unsaturated fatty acids (mostly oleic acid) accounted for 60–80% of the incorporated label if the plastids were illuminated, but in the dark or in the presence of DCMU the unsaturated acids accounted for only 0–15% of the label incorporated into lipid. The effect of ATP on incorporation was dependent on the maturity of the chloroplasts; mature pea chloroplasts were inhibited by ATP, whereas in developing plastids there was a slight stimulation by ATP. Inhibition of acetate incorporation into lipid by DCMU appears to be due to inhibition of noncyclic phosphorylation. Incorporation was restored by reduced 2,3,5,6-tetramethylphenylenediamine, which restored phosphorylation, but not by reduced N,N,N′,N′-tetramethylphenylenediamine.

Cell-free preparations of Chlorella pyrenoidosa catalyze the transfer of the fatty acyl moiety of fatty acyl CoA derivatives to sulfoquinovosyl monoglyceride to form sulfoquinovosyl diglyceride. This reaction is stimulated by Triton X-100 concentrations of up to 0.6 mg/ml and has a pH optimum of 7.7. Similar Chlorella preparations catalyze the stepwise removal of both fatty acyl groups from sulfoquinovosyl diglyceride to form sulfoquinovosyl monoglyceride and then sulfoquinovosyl glycerol. This reaction is inhibited by both calcium and magnesium. The nonionic surfactant Triton X-100 inhibits the enzymatic deacylation at concentrations of < 0.5 mg/ml but stimulates it at higher concentrations. The pH optimum for the deacylation of sulfoquinovosyl glycerides is 8.2, with little activity observed below pH 8. The enzymatic activities for both the transacylation and deacylation reactions are associated with a 30,000 g particulate fraction of Chlorella. Sulfoquinovosyl glycerol was found not to be an acceptor of the fatty acyl moiety of fatty acyl CoA derivatives. Methods are described for the preparation of sulfoquinovosyl monoglyceride, sulfoquinovose, and 3-sulfo-l,2-propanediol.

The positional isomers of the cyclopropane fatty acids of Clostridium butyricum phospholipids have been analyzed by capillary column gas-liquid chromatography. Greater than 95% of the methylenehexadecanoic acids was the 9,10 isomer. On the other hand, 60-70% of the hexadecenoic acid precursors was the Delta(7) isomer, and the remainder was the Delta(9) isomer. Of the methyleneoctadecanoic acids 75-80% was the 11,12 isomer, with the remainder being the 9,10 isomer. There were approximately equal amounts of the Delta(9)- and Delta(11)-octadecenoic acids in the phospholipids. This study reveals a surprisingly strong specificity of the cyclopropane synthetase for the (n-7) series of monoenoic fatty acids. An analysis by capillary column chromatography of the monoenoic and cyclopropane aldehyde dimethylacetals derived from the plasmalogens (1-alk-1'-enyl-2-acyl-glycero-phosphatides) of C. butyricum revealed the presence of the same positional isomeric mixtures of the 16- and 18-carbon monoenoic residues in approximately the same ratios as were found in the fatty acids. In the formation of the cyclopropane alk-1'-enyl ethers there was also specificity for the (n-7) series, but it was not as strong as that seen in the fatty acids. The ratio of the 7,8 isomer to the 9,10 isomer was higher in the methyl-enehexadecanals than in the corresponding fatty acids. This paper extends the use of Golay capillary columns to the analysis of the positional isomers of plasmalogen aldehydes as their dimethylacetal derivatives.

A fraction comprising about 0.7% of the extractable surface lipids of cabbage (Brassica oleracea) leaves was isolated and identified as a mixture of isomeric beta-hydroxyketones consisting mainly of 14-keto-16-hydroxynonacosane and 15-keto-13-hydroxynonacosane.

Whereas wild-type strains of Saccharomyces cerevisiae can synthesize up to 7% dry weight of ergosterol, a polyene-resistant mutant has been obtained which produces no ergosterol. Instead, a C-28 methyl sterol is produced, and it has been identified as Δ8(9),22-ergostadiene-3β-ol. This sterol is converted to ergosterol by wild-type yeasts and is observed transiently in cells during aerobic adaption of anaerobically grown wild-type yeasts. The new sterol is proposed as an intermediate in ergosterol biosynthesis.

The presence of a strong contact component in the sex and ovipositing behavior of the sheep blowfly Lucilia cuprina Wied. prompted an investigation into the chemical composition of the cuticular wax of the adult male and female flies as well as that of the blowfly puparia. Thin-layer chromatography indicated that the lipids in all the waxes examined comprise hydrocarbons, nonglyceryl esters, triglycerides, free fatty acids, and hydroxy compounds, probably diglycerides and monoglycerides. Phospholipids were not detected. Straight-and branched-chain saturated compounds, the latter often pre-dominating, are present in the hydrocarbon, free fatty acid, and ester fractions. Unsaturated molecules were absent. The hydrocarbons resemble those of the cricket to some extent, but the absence of unsaturated compounds is in striking contrast to both the cricket and the cockroach. Pheromones may be present in the low molecular weight fatty acids obtained on brief extraction of the insects.

SUMMARY Fatty acids of mitochrondria from hearts and livers of fresh-water and marine fish, marine birds, fur seal, and from sweet potato have been analyzed by gas-liquid chromatography. Cytochrome patterns, determined from difference spectra, were similar for all animal species ; the quantities of cytochromes varied slightly, heart mitochondria yielding higher values than the liver mitochondria in each species. Fish mitochondria showed a slightly lower cytochrome content than bird and mammalian mitochondria, while sweet potato particles contained very little cytochrome. Fatty acid patterns and degree of unsaturation were similar in mitochondria from fish and from fish-eating birds and seals. Major differences found in fatty acid patterns included: absence of detectable linoleic acid in liver mitochondria from sturgeon and flounder; absence of detectable arachidonic acid in mitochondria from sweet potato; a four-fold greater percentage of stearic acid and a four-fold greater percentage of combined linoleic-arachidonic acids in bird and seal mitochondria compared with those found in fish mitochondria; high levels of the ZinoZemte family of acids in fish mitochondria and intermediate levels in marine bird and seal mitochondria as compared to the high levels of the linoleate family of acids that have been found in rat liver, chicken liver, and beef heart mitochondria.

The hypothesis that depot fat is more unsaturated when it is synthesized at lower temperatures was tested in the mosquito. Female mosquitoes (Aedes sollicitans) were starved until no triglycerides remained. A single dose of sugar was fed and the mosquitoes were maintained at different temperatures. Approximately the same amount of triglyceride was synthesized per mosquito at each temperature, although at different rates. Mosquitoes maintained at low temperatures did not synthesize more unsaturated triglycerides than those at higher temperatures: the fatty acid composition was essentially the same from 10 to 35 degrees. The triglycerides synthesized from sugar contained no poly-unsaturated fatty acids. Total amounts and composition of phospholipid fatty acids remained unaltered during sugar feeding. When deprived of food, the mosquitoes catabolized triglyceride fatty acids randomly; cold-exposure did not cause selective retention or utilization of any individual fatty acid.

Complete structural characterization of the C18, C20, and C22, unsaturated acids of menhaden body oil is described. The present report brings to 23 the number of chemically defined unsaturated acids in this oil, accounting for 95 per cent of the total weight of unsaturated acids. Of these 23 acids, 7 have not previously been reported. Pure acids (or mixtures of positional isomers) were isolated by fractional crystallization, fractional distillation, counter-current distribution, rubber column chromatography, and preparative gas-liquid chromatography. Acids which were homogeneous in respect to chain length and number of double bonds were degraded by oxidative and reductive ozonolysis; fragments were identified by gas-liquid chromatography of the carboxylic acids and as addition-products of the aldehydes. Our studies of this complex oil, which is composed of more than 44 different acids, provide convincing evidence of the great usefulness of gas-liquid chromatography as a preparative and analytical procedure. Chemical characterization studies are now feasible on a microscale.

The acylation of lysophosphatidylcholine by enzyme preparations from spinach leaves was studied. The acylation reaction was followed by the incorporation of 14C- labeled fatty acids from the respective coenzyme A derivatives into phosphatidylcholine. The subcellular fraction with the highest specific activity was the microsomal fraction. Con- taminating thioesterase activity which was encountered was inhibited by treatment with sodium dodecyl sulfate. The acyl- transferase activity was only mildly inhibited by sulfhydryl reagents. Labeled fatty acid was primarily incorporated into phosphatidylcholine. When saturated and unsaturated fatty acyl CoA derivatives were used, the saturated derivatives were incorporated primarily into the 1-position of the glycerol moiety, and the unsaturated fatty acids went primarily to the 2-position. This pattern of incorporation agrees with the fatty acid distribution in vivo.

SUMMARY Fatty acids uiiiformly labeled with C14 were obtained by growing Penicillium javanieuru, in the presence of uniformly labeled acetate, on a nitrogen-deficient medium. When uniformly labeled acetate was the CI4 source, the specific activity of the linoleic acid was greater than the specific activity of the oleic acid. The reverse was true when uniformly labeled sucrose was the C14 source. It is suggested that the disproportionate labeling observed between oleic acid and linoleic acid is the result of changing relative rates of synthesis of these acids coupled with an acetate pool of changing specific activity.

Pure phosphatidyl ethanolamine and lecithin from egg yolks were fed to rats in saline or in olive oil and the changes in individual phospholipids in the intestinal wall, liver, and plasma of the animals were studied. Ingestion of olive oil alone produced increased levels of all phospholipid fractions in each of the three tissues. Feeding phosphatidyl ethanolamine in saline resulted in slightly in- creased plasma phospholipids, but levels of liver total phospho- lipids were greatly reduced; when phosphatidyl ethanolamine was fed with olive oil, liver phospholipids were again reduced but this reduction was confined to the phosphatidyl ethanol- amine and phosphatidic acid fractions. Feeding lecithin alone did not produce significant changes in levels of plasma or tissue phospholipids. The results suggest that liver phospholipid synthesis is de- pressed by feeding phosphatidyl ethanolamine ; in the presence of olive oil, hepatic synthesis of phosphatidyl ethanolamine seems to be more selectively inhibited. effects of feeding purified phosphatidyl ethanolamine (PE) and lecithin on the levels of individual phospho- lipids of the rat intestinal wall, plasma, and liver after this time interval. Since the phospholipids were fed in saline or in olive oil, the effect of the oil alone on phos- pholipid synthesis was also studied. In a previous study, Hill, Linazasoro, Chevallier, and Chaikoff (5) (who were concerned mainly with glucose metabolism in relation to fat feeding) observed that feed- ing certain fats to rats over a period of 3 days with 5oYO glucose in the diet did not affect the lipid levels of the liver or the phospholipid levels of plasma. It appears from the present work that feeding fat alone does in- fluence the levels of phospholipids in the liver and the plasma. The changes in levels of plasma and liver phos- pholipids produced during a single feeding are obviously due to a combination of endogenous changes and absorp- tion from the intestine. The effects of absorption have been further studied by feeding radioactively labeled phospholipids. These results will be reported later.

Plant leaf systems have been incubated under various conditions with uniformly labeled oleic acid, and the breakdown products identified by gas–liquid chromatography. Young green leaves of the castor plant (Ricinis gibsonii) and of the field pea plant (Pisum sativum) catabolize oleic acid by an oxygen-requiring pathway to heptadec-8-enal which is then dehydrogenated by an NAD-coupled mechanism to heptadec-8-enoic acid. Further α-oxidation occurs with the production of hexadec-7-enoic acid and lower homologues. The α-oxidizing ability is associated with the fraction of homogenized leaves that sediments between 700 and 7000 × g; the partly purified acetone powders of leaves retain this enzymatic activity in soluble form. Preliminary studies with uniformly labeled linoleic acid suggest that α-oxidation of polyunsaturated acids also occurs in the leaf systems.

Synthesis of 1-sn-phosphatidyl-3'-sn-glycero-1'-sulfate (phosphatidylglycero-1-sulfate) was achieved by monosulfation of 1-sn-phosphatidyl-3'-sn-glycerol (diphytanyl ether analog) with an equimolar amount of SO(3)-pyridine complex at room temperature; with excess sulfation reagent at 60 degrees C, the 1',2'-disulfate ester was obtained. The phosphatidyl-glycero-2-sulfate isomer was synthesized by an unambiguous route starting from the bacterial 2,3-di-O-phytanyl-sn-glycerol. The synthetic phosphatidylglycerosulfates were characterized by analytical, chromatographic, optical rotatory, and spectral (infrared and NMR) data and compared with the phosphatidylglycerosulfate isolated from Halobacterium cutirubrum.

Lipids of strain L fibroblasts (mouse), grown in chemically defined medium, contained approximately 20% 16:0, 5% 16:1, 20% 18:0, and 50% 18:1 acids; and small amounts of 12:0, 14:0, 15:0, 15:1, and 20:0 acids. No polyunsaturated acids, such as 18:2, were present. The distribution of the fatty acids in the phospholipids and triglycerides was similar. When grown in the presence of dialyzed serum, 18:2 acid was found in the cells and replaced 18:1 acid. Lipids of two lines of HeLa cells (human), grown with serum present, contained at least 20 fatty acids of which 16:0, 18:0, 16:1, 18:1, and 18:2 were dominant. The phospholipids contained considerably more 18:2 acid than did the triglycerides, the principal unsaturated acid in which was 18:1. Cells contaminated with pleuropneumonia-like organisms also showed this difference in distribution.

Myelin was prepared from the brachial plexus and cervical spinal cord of adult squirrel monkeys (Saimiri sciureus). Brachial plexus myelin contained a larger amount of sphingomyelin and smaller amounts of cholesterol, lipid galactose, ethanolamine phosphoglyceride, choline phosphoglyceride, and alk-1-enyl ether than spinal cord myelin when compared as ratios to total lipid phosphorus. The peripheral nervous system myelin had a higher proportion of protein. All of these differences were statistically significant. Thus peripheral nervous system myelin and central nervous system myelin differ in protein content and lipid composition in this subhuman primate.

The effect of microbiological deconjugation of bile acids on total bile acid and neutral sterol fecal excretion by adult male rats has been studied. A screening method utiliz- ing mice allowed selection of a Clostridium perfringens type A strain, which accelerated cholesterol catabolism in mice. When this species of bacteria was associated with germfree rats, the fecal bile acids were excreted as free bile acids (de- conjugated), however the quantities of bile acids excreted were not increased compared with those of germfree rats. Conven- tional rats excrete twice as much bile acids (all deconjugated) as do the germfree and C. perfringens-associated rats. It is, therefore, unlikely that the microbiological deconjugation of bile acids is responsible for the increased fecal excretion of bile acids seen in conventional rats. The C. perfringens-associated rats excreted identical kinds and quantities of fecal neutral sterols as did the germfree rats.

Measurements of the iodine value made over a period of three years demonstrate a regular yearly cycle in the composition of the fat of crustacean plankton in Lake Balaton. The melting point of the lipid of the planktonic copepods remained during the whole year somewhat lower than the water temperature. The proportions of the C20–C22 poly-unsaturated acids in the planktonic crustaceans increased with decreasing temperature and in some species exceeded the values characteristic of marine animals. In fresh-water fish, kept at room temperature and fed on freshly collected fresh-water plankton, the lipids formed in winter resembled marine fish oil. In the crustaceans raised on algae containing no fatty acids longer than C18, the C20-C22 acids always appeared as major components of the copepods.

Turnover of cholesterol in the American cockroach, Periplaneta americana (L.), was investigated by feeding cholesterol-4-C14 in the diet and examining periodically the specific radioactivity of the total carcass cholesterol. It was found that the movement of cholesterol into and out of the roach tissues was much slower than has been reported for mammals. The ester cholesterol pool was found to equilibrate slowly with the free cholesterol pool. At least 40% of the carcass cholesterol was found to be exchangeable with the dietary cholesterol.

Cell-free extracts of the protozoan Tetrahymena pyriformis have been found to catalyze the following reactions: Phosphatidylethanolamine + L-Serine Phosphatidylserine + Ethanolamine. Phosphatidylserine --> Phosphatidylethanolamine + CO(2) divided by Net: L-Serine --> Ethanolamine + CO(2). The biosynthesis of phosphatidylserine in this organism resembles that found in higher animals. In contrast, phosphatidylserine is formed in bacteria in a reaction between CDP-diglyceride and L-serine. A detailed description is presented of the enzyme that catalyzes the synthesis of phosphatidylserine in Tetrahymena by the exchange reaction, together with some properties of the phosphatidylserine decarboxylase in this organism.

The plant sulfolipid has been isolated from Chlorella pyrenoidosa cells and from alfalfa leaves by chromatography on Florisil and DEAE cellulose columns. The galactolipids, galactosyl diglyceride and digalactosyl diglyceride were isolated by further chromatography on silicic acid columns. The galactolipids from alfalfa leaves were highly unsaturated and contained 87–94% linolenic acid, while the sulfolipid contained approximately equal amounts of palmitic and linolenic acids.

The nonpolar (acetone-soluble) lipids of the extremely halophilic bacterium, Halobacterium cutirubrum, were found to consist of red carotenoid pigments (43%) and squalenes (48%) with a small amount of a vitamin K-type quinone. The squalenes were shown by n.m.r. and mass spectra to consist of the fully isoprenoid squalene (S; C3OH5o), dihydrosqualene (S2; CJ&152), and tetrahydrosqualene (S4; C30H54) in the ratio of 1.0:0.4:0.1. S2 probably has one re- duced internal isoprenoid group, and S4 has one internal and one terminal reduced isoprenyl group. The vitamin K-type quinone was shown by n.m.r. and mass spectra to have a Cho isoprenoid side chain, and is thus identified as menaquinone-8 (MK-8).

An analysis of the lipids of the bacterium Serratia marcescens has shown that palmitic acid and 9,10-methylenehexadecanoic acid constitute about 75% of the total fatty acids. Monounsaturated acids account for only about 10% of the total fatty acid and consist predominantly of 9,10-hexadecenoic acid (palmitoleic acid) and 11,12-octadecenoic acid (vaccenic acid). Three hydroxy acids that may function as intermdiates in the biosynthesis of unsaturated fatty acids have also been isolated and characterized.

Myelin phospholipids have been examined by a separation-reaction-separation procedure for two-dimensional thin-layer chromatography on silica gel. After separation in one dimension, alk-1-enyl groups are cleaved by exposure of the plates to HCl fumes. Development in the second dimension quantitatively separates acid-labile and acid-stable phosphoglycerides as well as the aldehydes released from the acid-labile phosphoglycerides. Myelin phospholipids from the central nervous systems of the rhesus monkey, squirrel monkey, ox, and mouse contain 32-36% acid-labile ethanolamine phosphoglycerides (ethanolamine plasmalogens) and 8-14% acid-stable ethanolamine phosphoglycerides. Acid-labile choline and serine phosphoglycerides account for less than 1% of the myelin phospholipids.

Publisher Summary Adenosine-5′-diphosphoglucose (ADP-glucose) is found in acid and alcoholic extracts of plants and bacteria. There is no specific method for the determination of ADP-glucose. ADP-glucose can be converted to ATP and G-1-P with the help of inorganic pyrophosphate (PPi) and ADP-glucose pyrophosphorylase. This specific reaction is the basis for the method for the determination of ADP-glucose. The method has application in biochemistry. The principle behind the method is that the increase of NADPH, as measured by the change in extinction at 340 (334, 365) nm, is proportional to the amount of ADP-glucose present. The pH optima of the enzymes catalyzing reactions are between 7.5 and 8.5; therefore, the measurements should be made in this range. Spectrophotometer or spectrum-line photometer is suitable for accurate measurements at 340 nm, 334 nm, or 365 nm. The chapter discusses the purity of reagents. The enzymes should be free from PPi. The enzymes must not contain any NADPH oxidase.

Publisher Summary This chapter describes the development and clinical studies of antiparasitic agents. A summary of the structures of 24 antimalarial drugs from eight chemical classes in general use is presented. The phenanthrene methanol WR33063 cured a high percentage of human volunteers infected with several Plasmodium falciparum strains, including chloroquine-resistant ones, without evidence of phototoxicity or other serious side effects, although occasionally a treatment failure occurred, even at the largest doses used in therapy and such failures might be due to drug resistance. WR33063 did not protect volunteers from chloroquine and pyrimethamine-resistant P. falciparum infection when given prophylactically. The quinolize methanol WR30090 likewise demonstrated effective antimalarial action, with low toxicity, against multidrug-resistant P. falciparum and Plasmodium vivax in human volunteers. An observation that a meticlorpindol-tolerant strain of E. acervulina showed greater than expected sensitivity to decoquinate led to a synergistic drug combination of a 4-hydroxyquinoline coccidiostat plus meticlorpindol, which was effective at lower levels than those used for either coccidiostat alone.

Publisher Summary This chapter discusses the recent progress with laser microbeams. The chapter deals with a description of the way in which the laser microbeam is being used to irradiate several organelles for the purpose of studying cell function and development. Chromosomes are the organelles that have been studied most extensively with the argon laser microbeam. The first argon laser microbeam study described the effect of focusing a low-power beam onto the long arm of a chromosome in a mitotic salamander tissue culture cell. The cells had been treated with a low concentration of the dye, acridine orange (AO), thus photosensitizing them to the laser light. This initial study demonstrated the feasibility of chromosome studies, and has resulted in numerous investigations designed to clarify the structure and function of the eukaryote chromosome. The functional assay of nucleolar formation tends to confirm the cytochemical evidence, DNA can be altered, and a nucleolus is not synthesized; histone can be altered selectively, and a nucleolus is formed-the DNA is still functional. Furthermore, these studies also demonstrate the directed loss of a specific genetic function.

Publisher Summary Several yeast species produce nonlethal respiratory-deficient mutants that have lost the ability to grow on nonfermentable substrates, such as glycerol, but do grow on fermentable substrates, such as glucose. Several types of mutations affecting mitochondrial inner membrane components have been obtained in Saccharomyces cerevisiae. The obtention of these mutants that can be of either cytoplasmic or chromosomal heredity has been described in this chapter. In S. cerevisiae, the screening of chromosomal respiratory-deficient mutants may be complicated by the high yield of cytoplasmic mutations induced by most of the mutagenic treatments. Moreover, a large number of chromosomal mutants are difficult to handle because they spontaneously give rise to cytoplasmic mutants. The use of “petite-negative” yeast species, unable to produce cytoplasmic mutations, is thus of great help in obtaining stable mitochondrial mutations of chromosomal heredity. Schizosaccharomyces pombe is of particular interest in this respect because its physiological and genetic properties are rather well known.

3 pages, 1 scheme.-- Part IV in the series "Chromenes and Chromones". For Part III see González, A.G., Castañeda, J.P. and Fraga, B.M. (1974) Anal. Quim. 70, 452., From the stems of Cneorum tricoccum L. 3,3-dimethylallylspatheliachromene, spatheliabischromene and alloptaeroxylin methyl ether have been isolated as well as the new natural product ptaerochromenol methyl ether, which was chemically interconverted to isoheteropeucenin methyl ether., This work forms part of the Programme of Chemistry 1971 conceded by the Foundation "Juan March".

This chapter provides an overview of mitochondria, chloroplasts, and bacteria. Mitochondria and chloroplasts have a number of structural and biochemical properties in common and also some properties in common with those of certain bacteria. Both mitochondria and chloroplasts are bound by two membranes, the inner one of which is continuous, in places, with internal membranes that lie in a space containing proteins in solution. The diversity of shapes, sizes, number, and arrangements of the cristae membranes of mitochondria is matched by the variety of form of the internal membranes of chloroplasts. The chapter also discusses the evolutionary origin of mitochondria. There are two theories attempting to account for the evolutionary origin of mitochondria: the endosymbiont theory and the episome theory.

Publisher Summary Adenylate cyclase from Brevibacterium liquelaciens catalyzes the conversion of ATP to 3', 5'-cyclic AMP (cAMP) and PPi ( forward reaction ) as well as the formation of ATP from 3', 5'-cAMP and PPi (reverse reaction). The enzyme requires a divalent metal ion, such as Mg 2+ , and α-keto acid, such as pyruvate, for maximum activity. Therefore, the enzyme assay for both forward and reverse directions is conducted in the presence of Mg 2+ and pyruvate. The assay of reverse reaction is based on the enzymatic determination of ATP formed from cAMP and PP i using a fluorometric method. This assay is not suitable for crude fractions which are not yet highly purified and contain a considerable amount of enzymes interfering with the reverse reaction, such as inorganic pyrophosphatase, ATPase, and adenylate kinase. However, it can be used after the ammonium sulfate step and is employed routinely for monitoring the enzyme activity in the column eluates, because it is much easier and quicker than the forward procedure.

Topics discussed are: some chemical characteristics of the tetra-, penta-, and hexathionate ions; structures of the tetra-, penta-, and hexathionate ions and the seleno- and telluropentathionate ions; reactions of the penta-, selenopenta-, and telluropentathionate ions with methylxanthate ions, and structures of reaction products; the prevalence of unbranched sulphur chains.

Publisher Summary The assay described in this chapter is a sensitive, rapid, one-step reaction using a long-lived isotope. Because tritium-labeled adenosine is measured, the enzyme can be assayed in the presence of levels of inorganic phosphate (as encountered in some crude fractions) that preclude colorimetric determination of enzymatically released inorganic phosphate. The enzyme is widely distributed and has been demonstrated in a large variety of tissues including plant material, bacteria, snake venom, and numerous mammalian tissues.