Vernon H. Cheldelin

Nutrition and metabolism of methyl donors and related compounds in the blowfly, Phormia regina (Meigen).

Abstract In addition to carnitine and 2,2-dimethylaminoethanol, γ-butyrobetaine and O -acetylcarnitine are shown to be effective replacements for choline in the diet of P. regina , an organism which shows a choline requirement when grown on a chemically defined diet under sterile conditions. dl -Carnitine is shown to be approximately equivalent to choline in the diet on a molar basis and slightly more effective than γ-butyrobetaine. The choline inhibitor 2-amino-2-methylpropanol is shown to be effective in P. regina , and its effects can be reversed by those compounds which are able to replace choline in the diet as well as by choline itself. The order of effectiveness is choline > 2,2-dimethylaminoethanol > γ-butyrobetaine > carnitine. Phospholipides containing serine, ethanolamine, and choline are shown to be normal constituents of the third instar larvae. Formate although apparently not being used in the biosynthesis of methyl groups for choline synthesis is shown to be metabolized to CO 2 both by the whole organism and by larval homogenates. The biosynthesis of choline from ethanolamine is shown either not to occur or to be unimportant in P. regina .

The isolation of a methylcholine containing phospholipid from Phormiaregina larvae

Abstract Although carnitine, β-hydroxy-γ-butyrobetaine, occurs in many animal systems, its function and intermediary metabolism remains obscure (Fraenkel 1957). The results of previous experiments in our laboratory indicated that on a chemically defined diet, carnitine and several related compounds, including γ-butyrobetaine, etc., replaced the choline requirement. (Hodgson, Cheldelin and Newburgh 1956, 1960). Since choline is a major constitent in Phormia regina phospholipids it seemed reasonable to postulate that when larvae are reared on a diet devoid of choline but containing carnitine, a phospholipid in which choline is replaced by carnitine might be observed. This communication reports the formation of a new “lecithin” when blowflies are reared in the presence of carnitine.

Enzyme studies of various stages of the blowfly Phormia regina (meig.)

Abstract Investigations on carbohydrate dissimilation in the blowfly Phormia regina have been conducted. Extensive citric acid cycle activity was found to be localized in adult mitochondria, but could not be demonstrated in larvae. Cytochrome oxidase activity was greater in the adult than in larvae. Glycolysis and the pentose cycle system were present in soluble fractions from both the adult and larvae, and the pentose cycle was also indicated in the egg. The presence of three TPN-specific enzymes was demonstrated: isocitric, G-6-P, and 6-PGA dehydrogenases.

Oxidations in Acetobacter suboxydans

Abstract 1. 1. Cell-free extracts have been prepared from A. suboxydans , which are capable of catalyzing the following reactions: 1.1. ethanol → acetaldehyde 1.2. glycerol → dihydroxyacetone → a new carbonyl-type compound and other unknown products 1.3. glucose → unknown products 1.4. pyruvate → acetaldehyde 1.5. acetaldehyde → acetate 2. 2. Ethanol dehydrogenase has been prepared in highly purified form (14,000 Racker units per mg). It is DPN-dependent. 3. 3. The cell-free extracts (as well as intact resting cells) were unable to appreciably dissimilate acetate or intermediates of the tricarboxylic acid cycle. Glycolysis intermediates were also inert, and it is concluded that neither glycolysis nor the TCA cyclic oxidation pathway is operative to any significant degree in this organism. 4. 4. A non-enzymatic interaction between dihydroxyacetone and DPN is described. The product shows the sam absorption behavior as reduced DPN, although it cannot be reoxidized by acetaldehyde.

Oxalate oxidation by an obligately parasitic fungus Tilletia contraversa.

Abstract Enzyme preparations from teliospores of Tilletia contraversa oxidize oxalic acid to carbon dioxide and probably hydrogen peroxide. The oxidation is maximum near pH 2.6 and is 50% inhibited by 2.4 × 10 −4 M fluoride and by 1.6 × 10 −2 M cyanide. The oxidation is stimulated by riboflavine and flavine mononucleotide, but not by flavine adenine dinucleotide.

Carbon dioxide fixation and biosynthesis of amino acids in yeast

Abstract The time required for the label from 14 CO 2 to enter the various amino acids of yeast protein has been studied by means of paper chromatography and radioautography. Glutamic acid, aspartic acid and threonine become radioactive within the first 1 2 hour, emphasizing their rapid equilibrium with the primary products of 14 CO 2 fixation. Glycine and serine become radioactive by the end of the first hour and remain among the most radioactive of the amino acids throughout the period studied. This observation supports a previous proposal for the biosynthesis of these amino acids from a four carbon intermediate, which is probably one of the first formed carbon dioxide fixation products. Proline incorporates label very slowly and lysine not at all. These findings are in line with a slow turnover rate for proline and the known biosynthetic pathway for lysine. Valine labeling appearing before that in alanine suggests a decarboxylation-recarboxylation step in the formation of valine.

Pantothenic Acid Derivatives and Growth of Acetobacter suboxydans

Summary 1. Various derivatives of pantothenic acid have been compared for growth promoting activity in A. suboxydans. The order of effectiveness is roughly Co A† = LBF-γ-phosphate >LBF = PA-cysteine (approx.) >PA = pantoic acid >LBF-diphos-phate >PA phosphates, with Co A and LBF-γ-phosphate about 10 to 20 times as active as PA. The derivatives containing -SH groups appear to be active principally, or even exclusively, in the reduced state. 2. It is concluded that the “A. suboxydans stimulatory factor” is multiple in nature, but is not identical with pantothenic acid phosphates.

OXIDASE ACTIVITY AND LIPID COMPOSITION OF RESPIRATORY PARTICLES FROM CLAVICEPS PURPUREA (ERGOT FUNGUS).

Abstract Respiratory particles with complete succinate and DPNH oxidase systems were prepared from vegetative cultures of Claviceps purpurea . The rates were 4–10 μmoles of succinate per hour per milligram protein at 36 °C and 20–24 μmoles of DPNH oxidized per hour per milligram at 27 °. Beef heart cytochrome c increased oxidase activity and antimycin A and cyanide completely inhibited the oxidase activity. The succinate oxidase system is rapidly disintegrated by sonic irradiation. Claviceps purpurea respiratory particles contained 26% lipid and 58% protein. There were no plasmalogens. Claviceps purpurea respiratory particles contained 10 μmoles of phosphorus per milligram lipid. The percentage of the various phospholipids was phosphatidylinositol, 28; phosphatidylcholine, 27; phosphatidylserine, 13; phosphatidylethanolamine, 18; polyglycerophosphate, 7; and residue, 7. Coenzyme Q 10 (H-10) is a component of the C. purpurea respiratory particles. Claviceps purpurea respiratory lipid was slightly more effective than beef heart mitochondrial lipid in restoring the succinate-cytochrome c reductase activity of acetone-extracted beef heart mitochondria.

Growth Stimulation of Lactobacillus gayoni by N-D-Glucosylglycine.

Summary 1. For rapid initiation of growth of L. gayoni, the culture medium required heating. 2. This heat activation reaction, involving glucose, salts A and glycine, appeared to proceed through an intermediate, N-D-glucosylglycine, and then into at least two heat stable growth factors. 3. One of these factors could also be derived by heating glucose under alkaline conditions.

B Vitamins in Germinating Seeds.

Summary Germination of seeds is accompanied by increases in the content of most B vitamins. The increases are greatest for nicotinic acid, followed by pyridoxin, pantothenic acid, riboflavin, inositol and biotin in approximately the order named. Thiamin is a borderline case. Folic acid is seen to decrease substantially in peas and in one sample of lima beans. Contents of B vitamins in growing corn and beans are found to reach a peak at a relatively early stage of development, after which the amounts present decrease steadily as the seeds mature.