A.A. Benson

Leaf methanol — the simplest natural product from plants

Current interest in the chemistry of the atmosphere has led to the identification of methanol as one of the major organic compounds in forest air and in the troposphere. Analysis of the emissions of volatile organic compounds from leaves has revealed that most plants emit methanol, especially during early stages of leaf expansion — it is probably produced as a by-product of pectin metabolism during cell wall synthesis, and a fraction of this pool is then emitted through stomata during transpiration. There is also evidence that leaf methanol supports an abundant population of epiphytic bacterial methylotrophs. Application of methanol to leaves enhances the growth and yield of C 3 plants, although the mechanism responsible for this phenomenon is uncertain.

Petroleum hydrocarbons: uptake and discharge by the marine mussel Mytilus edulis.

The common marine mussel Mytilus edulis has been observed to rapidly take up mineral oil, [14C]heptadecane, 1,2,3,4-tetrahydronaphthalene, [14C]toluene, [14C]naphthalene, and [3C]3,4-benzopyrene from seawater solution. This species of mussel did not metabolize any of these compounds, and transfer of the mussel to fresh seawater, after exposure to the hydrocarbon in solution, resulted in the discharge of most of the hydrocarbon, although significant amounts remained (between 1 and 400 micrograms per mussel). The nontoxic paraffinic hydrocarbons mineral oil and heptadecane were taken up (10 milligrams per mussel) to a much greater extent than the aromatic hydrocarbons (2 to 20 micro-grams per mussel).

The Path of Carbon in Photosynthesis. XXI. The Cyclic Regenerationof Carbon Dioxide Acceptor

IJCEL-2369 Unclassified Chemistry D i s t r i b u t i o n UNIVERSITY O CALIFORML4 F Radiation Laboratory Contract No. M-7405- eng THE P T O CARBON I N PHdGSYNTHESIS .BI. A H F T E CYCLIC REGENERATION O CARBON DIOXIDE ACCEPTOR H F J. A , Bassham, &Ae A. Benson, Lorel D. K r ~ r ~ Anne Z. Harris, A. T. Wilson and M. Calvin October, 1953 Berkeley, California

The biochemistry of arsenic

Abstract The process of arsenic detoxification in marine algae has revealed basic mechanisms for the action of arsenic on cells and their proteins.

Plant phospholipids I. Identification of the phosphatidyl glycerols

Abstract 1. 1. The phospholipids of Scenedesmus and higher plants have been separated into at least three fractions by two-dimensional paper chromatography. These have been deacylated to yield glycerophosphorylcholine, glycerophosphorylglycerol and glycerophosphorylinositol. 2. 2. The phosphatidyl glycerol fraction has been identified by hydrolysis of the purified lipid to give glycerophosphorylglycerol in 95% yield. 3. 3. The presence of two free hydroxyl groups in the phospholipid was demonstrated by its conversion to an isopropylidene derivative and by oxidation by lead tetraacetate. 4. 4. These lipids possess almost half of the lipid phosphorus in some plants and appear to be ubiquitous in nature.

The path of carbon in photosynthesis of the lipids.

Abstract The rates of C 11 incorporation into lipids and their components during steady-state photosynthesis in C 11O 2 by Chlorella pyrenoidosa reveal the metabolic importance of the galaclolipids and phosphatidyl glycerol. The most, rapidly labeled of the water-soluble deacylation products were galactosyl glycerol, digalactosyl glycerol, diglycerophosphate, sulfoglycosyl glycerol, and glycerophosphorylinositol. Labeling of the triglycerides proceeded more slowly than that of any of the surfactant lipids. Acid hydrolysis of the labeled galactolipids demonstrated active exchange of the galactose moieties with the intermediates of hexose photosynthesis and relatively slower labeling of the associated glycerol or fatty acids. However, the fatty acids of phosphatidylglycerol and the galactosyl diglycerides were more rapidly labeled than any other esterified fatty acids. Periodate oxidation of diglycerophosphate from phosphatidylglycerol indicated uniform labeling before 5 min. of steady-state photosynthesis. Possible metabolic sequences in the biosynthesis of the galactolipids and the phosphatides are discussed. The remarkable metabolic activity and high concentrations of phosphatidyl glycerol and the galactolipids in Chlorella attest to their importance in photosynthesis.

Specificity of digestive lipases in hydrolysis of wax esters and triglycerides studied in anchovy and other selected fish

The physiological specificity of fat digestion in several species of marine fish was studied by incubating a variety of synthetic and natural lipid substrates in fish intestinal fluid. Wax ester and triglyceride hydrolyses were studied in vivo and in vitro. In vivo feeding studies showed triglyceride hydrolyses and reesterification in the gut occurred 4 times faster than wax ester metabolism. In vitro comparisons of wax and triglyceride lipolysis always showed triglycerides to be hydrolyzed faster than wax esters; however, wide variation in the ratio occurred among different batches of intestinal juice. Ca. 50% of the 2-monoglycerides formed in the lipolytic sequence were hydrolyzed. Esters of lipase resistant fatty acids (20∶4 and 20∶5) were cleaved faster than normal fatty acid esters (18∶2 and 18∶3). Two of the species studied, the northern anchovy,Engraulis mordax and the jack mackerel,Trachurus symmetricus, empty lipase(s) into their gall bladders and produce phospholipid-free bile.

Neutron activation paper chromatographic analysis of phosphatides in mammalian cell fractions

Abstract Diphosphatidylglycerol (cardiolipin) was found in the mitochondria of a number of cell fractions. Its concentration was estimated by neutron activation chromatographic analysis of the deacylated derivative, 1,3-diglycerophosphoryl-glycerol. Microsomes contained little or none of this lipid. The distributions of the other glycerol phosphatides in mitochondria and microsomes were similar. A possible functional role for diphosphatidylglycerol is discussed.

Phytol metabolism in the bovine

Summary 1. Phytol, dihydrophytol and phytanic acid were identified in amounts below 1% of the total lipids in rumen contents from two normal lactating Holstein cows. The plasma level of phytanate measured in one of these animals was of the same magnitude as that found in the rumen and that reported in milk fat. 2. A tracer experiment with uniformly 14 C-labeled phytol indicated conversion to dihydrophytol and phytanic acid in the rumen. Only free phytol, as opposed to that on chlorophyll, appeared to be hydrogenated. 3. The relationship of these findings to high levels of phytanic acid detected on occasions in cow blood lipids and to the human affliction known as Refsums syndrome is discussed. 4. Thin-layer and gas-chromatographic techniques useful in the isolation, identification and analysis of phytol and some of its derivatives were developed.

Partial characterization of the bile salt-dependent triacylglycerol lipase from the leopard shark pancreas

Leopard shark triacylglycerol lipase has been characterized as a crude pancreatic preparation. The enzyme demonstrated an absolute requirement for trihydroxy bile salts for activity with natural bile salts of the shark giving a 4-fold greater stimulation of activity than pure sodium taurocholate. Bile salts also protected the enzyme from apparent inactivation by p-chloromercuribenzoate and trypsin treatment. The shark lipase demonstrated a temperature optimum of 36 degrees C and was rapidly inactivated at 50 degrees C even in the presence of bile salts. Divalent metal ions were required for activity with Ca2+ providing the greatest stimulation. At 22 degrees C, pH 8.5 and in the presence of natural bile salts, the apparent V was about 0.6 mumol fatty acid released/min per mg protein. The shark enzyme hydrolyzed over 90% of the fatty acids from trioleovylglycerol and methyl esters of pancreatic lipase-resistant fatty acids were hydrolyzed at the same rate as typical fatty acid methyl esters. Hydrolysis of triacylglycerol proceeded about ten-times faster than wax ester hydrolysis. The kinetic properties of the leopard shark enzyme were compared to other bile salt-dependent lipolytic enzymes. Pancreatic lipase activity was not detected.