A bacterium capable of using phytol as its sole carbon source, isolated from algal sediment of Mud Lake, Florida

A species of Flavobacterium that consistently attacks pure phytol and can use it as a sole source of carbon has been isolated from the blue-green algal sediment of Mud Lake, Florida. Biochemical tests demonstrate that this bacterium also readily uses various other organic compounds. This bacterium may account for the degradation products of chlorophyll and its side chain phytol, which have been found in the Mud Lake algal sediment. Phytol and its degradation products play a role in Refsum's disease, but phytol is also the most promising precursor of the isoprenoid hydrocarbons found in oil shale of the Green River Formation (Eocene) of Colorado, Utah, and Wyoming. The discovery of this species of Flavobacterium is a significant product of a protracted study of the bacteriology, phycology, zoology, and geochemistry of the algal sediment forming in Mud Lake, which is believed to be a modern analogue of the kind of algal sediment that, through geologic time, became oil shale.

Feline attractant, cis,trans-nepetalactone: metabolism in the domestic cat

cis,trans-Nepetalactone, the biologically active component of catnip, was force-fed to the domestic cat. When the (14)C-labeled compound was fed, 86 to 94 percent of the radioactivity was recovered in the urine, 1 to 2 percent was found in the feces, and 1 to 12 percent was collected as carbon dioxide. The major (50 to 75 percent) metabolite was alpha-nepetalinic acid, which was excreted in the urine together with small amounts of dihydronepetalactone, unchanged cis,-trans-nepetalactone, and several unidentified compounds. No marked physiological or histological eflects were observed when 20 to 80 milligrams of cis, trans-nepetalactone was administered orally. This is the first report on the metabolism of a mammalian attractant.

Metabolism of camphors and related compounds

1. The metabolism of (+/-)-norcamphor, (+)-camphor, (-)-camphor, (+)-epicamphor, (+/-)-camphorquinone, (+/-)-camphane-2,5-dione and camphane was investigated in rabbits. All the compounds except camphane-2,5-dione increased the content of glucuronide in the urine. 2. (+/-)-Norcamphor was reduced to endo-norborneol; (+)-camphor, contrary to expectation, was reduced to (+)-borneol, as well as being hydroxylated to (+)-5-endo-hydroxycamphor and (+)-3-endo-hydroxycamphor, 5-endo-hydroxycamphor being the predominant product. (+)-Epicamphor was reduced mainly to (+)-epiborneol; (+/-)-camphorquinone gave 3-endo-hydroxycamphor and 2-endo-hydroxyepicamphor, the former being the major metabolite. (+/-)-Camphane-2,5-dione was reduced to 5-endo-hydroxycamphor. Camphane was hydroxylated to borneol and epiborneol, the latter predominating. 3. An explanation of these findings is given in terms of steric hindrance and thermodynamic stability. 4. The possibility was investigated that NADH was involved in the reductions.

Mechanism of squalene biosynthesis: evidence against the involvement of free nerolidyl pyrophosphate

Several mechanisms that utilize farnesyl pyrophosphate and nerolidyl pyrophosphate as condensing substrates have been postulated for the asymmetric condensation reaction in squalene biosynthesis. Although there is ample evidence that farnesyl pyrophosphate is a substrate for this reaction, there has been no information concerning the role of nerolidyl pyrophosphate. We have made the following observations that demonstrate that nerolidyl pyrophosphate cannot be a free intermediate in squalene biosynthesis. (a) There is no significant interconversion of farnesyl pyrophosphate and nerolidyl pyrophosphate in a squalene-synthesizing system from yeast. (b) Nerolidyl-1-(3)H(2) pyrophosphate is not converted to squalene in the presence or absence of farnesyl pyrophosphate. (c) The addition of unlabeled nerolidyl pyrophosphate to incubation mixtures does not alter the relative loss of alpha-hydrogens from farnesyl pyrophosphate during its conversion to squalene. The synthesis of nerolidyl-1-(3)H(2) pyrophosphate is described. Chromatographic methods for the separation of pyrophosphate esters of triprenols and terpenols are included.

Analogues of geranyl pyrophosphate as inhibitors of prenyltransferase

Six analogues of geranyl pyrophosphate (the monophosphates of geraniol and tetrahydrogeraniol, and the pyrophosphates of nerol, octan-1-ol, tetrahydrogeraniol and citronellol) were synthesized, and were found to be inhibitors of pig liver prenyl- (geranyl-)transferase. The effects of each analogue were analysed in kinetic experiments, which showed the pyrophosphates of citronellol, tetrahydrogeraniol and octan-1-ol to be the most potent inhibitors. The results are interpreted to support a previous hypothesis that the main forces in the binding of substrates to prenyltransferase are non-specific lipophilic forces and a pyrophosphate-binding force.

Synthesis of 10,11-dihydrofarnesyl pyrophosphate from 6,7-dihydrogeranyl pyrophosphate by prenyltransferase

The syntheses of 6,7-dihydrogeraniol and of its pyrophosphate are described. It is shown that this analogue of geranyl pyrophosphate is a substrate for liver prenyltransferase and that the product synthesized by this enzyme from it and isopentenyl pyrophosphate is 10,11-dihydrofarnesyl pyrophosphate. The K(m) value for 6,7-dihydrogeranyl pyrophosphate was determined to be 1.11+/-0.19mum as compared with 4.34+/-1.71mum for geranyl pyrophosphate. The maximum reaction velocity with the artifical substrate was, however, only about one-fourth of that observed with geranyl pyrophosphate. The binding of isopentenyl pyrophosphate to the enzyme was not affected by the artificial substrate.

Absorption of chlorophyll phytol in normal man and in patients with Refsum's disease

This study was made to determine the extent of absorption of chlorophyll phytol from the intestine of man, and the importance of chlorophyll as a source of the phytanic acid that accumulates in Refsum's disease. Uniformly (14)C-labeled pheophytin a (the Mg-free derivative of chlorophyll a) was fed to normal human subjects and to patients with Refsum's disease. Feces were collected and analyzed. In all subjects, 90-95% of the administered radioactivity was recovered in the feces, still largely in the form of pheophytin a. The phytol radioactivity recovered in the feces averaged about 95% of that in the administered material, which indicates that there had been little absorption of the phytol moiety. Similarly, after 250 g of cooked spinach had been fed to a normal subject, almost the entire phytol content was found in the feces. Less than 5% of the ingested spinach phytol was accounted for in the thoracic duct lymph of another subject. It was concluded that not more than about 5% of the ingested chlorophyll phytol is absorbed by man, whether normal or afflicted with Refsum's disease. On this basis we conclude that the major portion of the phytanic acid that accumulates in Refsum's disease could not be derived from dietary chlorophyll.

The bacterial transformation of abietic acid

An Alcaligenes species, which was isolated from soil, can utilize abietic acid as its sole carbon source. During growth, the bacterium transforms abietic acid into 5alpha-hydroxyabietic acid (I, R=OH), a product considered to be 7beta-hydroxy-13-isopropyl-8xi-podocarp-13-en-15-oic acid (II, R=H) and a compound, C(20)H(28)O(3), which is believed to be an epoxy-gamma-lactone.

On the origin of pristane in marine organisms

Phytol-U-(14)C was adsorbed on algae and ingested in this form by zooplanktonic copepods (two species of Calanus). The lipids of these animals were analyzed after 48 hr and found to contain radioactive pristane and radioactive phytanic acid. The conversion of phytol to pristane by the copepods is interpreted as a likely biological source of pristane in nature.

Studies in phytosterol biosynthesis. Mechanism of biosynthesis of cycloartenol

1. The mechanism of cycloartenol biosynthesis in leaves of Solanum tuberosum was investigated with the use of [2-(14)C,(4R)-4-(3)H(1)]mevalonic acid. 2. The (3)H/(14)C atomic ratio in cycloartenol was 6:6, the same as that in squalene; this eliminates lanosterol as a possible biosynthetic precursor of cycloartenol, and indicates that a hydrogen migration from C-9 to C-8 occurs. 3. Chemical isomerization of the cycloartenol to lanosterol ((3)H/(14)C ratio 5:6) and parkeol ((3)H/(14)C ratio 6:6) confirms the hydrogen migration from C-9 to C-8. 4. Possible mechanisms for the biosynthesis of cycloartenol and parkeol are discussed. 5. The (3)H/(14)C ratio for 24-methylenecycloartanol was 6:6, demonstrating that the hydrogen atom at C-24 is retained during alkylation of the cycloartenol side chain.

Absorption of phytol from dietary chlorophyll in the rat

The fate of ingested chlorophyll-particularly of the phytol portion of the molecule-was studied. Uniformly (14)C-labeled pheophytin a (the Mg-free derivative of chlorophyll a) was prepared from an extract of tobacco leaves grown in (14)CO(2), and was administered by stomach tube to rats in which the thoracic duct had been cannulated. Only about 2% of the administered radioactivity was absorbed in 24 hr, largely into the thoracic duct lymph. Moreover, only a fraction of this lymph radioactivity was derived from phytol (i.e., was found in phytol, phytenic acid, or phytanic acid). The results indicated that not more than 1-2% of chlorophyll phytol is available for absorption by the rat. Similarly, after the administration of whole spinach or spinach extract (not labeled) to rats, only about 1% of the total phytol content was absorbed into the intestinal lymph. Nearly all of the administered phytol was found in the feces and the contents of the colon, and was still largely in the form of pheophytin. The study also indicated that little of the nonphytol portion of the chlorophyll molecule is absorbed.

Incorporation of DL-[2-14C]mevalonic acid lactone into beta-carotene and the phytol side chain of chlorophyll in cotyledons of four species of pine seedlings

1. The incorporation of dl-[2-(14)C]mevalonic acid lactone into beta-carotene and the phytol side chain of chlorophyll has been investigated in cotyledons of four species of pine seedlings (Pinus silvestris, P. contorta, P. radiata and P. jeffrei) grown in darkness and in light. 2. The relative incorporation of label into beta-carotene and the phytol side chain of chlorophyll is similar to that observed in experiments on monocotyledons and dicotyledons. 3. The relative incorporation of (14)CO(2) into beta-carotene and phytol is much higher than the incorporation of [2-(14)C]mevalonic acid.

The subcellular distribution and biosynthesis of castaprenols and plastoquinone in the leaves of Aesculus hippocastanum

Intact chloroplasts and cell walls were prepared from horse-chestnut leaves that had previously metabolized [2-(14)C]mevalonate. The bulk of the castaprenols and plastoquinone-9 was found within the chloroplasts. The remaining portion of the castaprenols was associated with the cell-wall preparation whereas that of the plastoquinone-9 was probably localized in the soluble fraction of the plant cell. The (14)C content of these compounds of different cell fractions indicated the presence of polyisoprenoid-synthesizing activity both inside and outside the chloroplasts. This was confirmed by the relative incorporation of (14)C when ultrasonically treated and intact chloroplasts were incubated with [2-(14)C]mevalonate. As the leaves aged (on the tree) an increase in extraplastidic castaprenols and plastoquinone-9, together with associated synthesizing activities, was observed.