Studies in relation to biosynthesis. XLI. Canescin

1969 ◽  
Vol 22 (11) ◽  
pp. 2429 ◽  
Author(s):  
AJ Birch ◽  
F Gager ◽  
L Mo ◽  
A Pelter ◽  
JJ Wright
Keyword(s):  
Citric Acid ◽  
Carbon Atom ◽  
Citric Acid Cycle ◽  
Lactone Ring ◽  
Carbon Chain ◽  
The Other ◽  
Methoxyl Group ◽  
Acid Cycle ◽  
Polyketide Chain

The biosynthesis of canescin (I) has been investigated. The isocoumarin portion is derived from a polyketide chain. One carbon atom of the γ- lactone ring and the carbon atom of the methoxyl group originate from methionine whilst the other three carbon atoms of the γ-lactone have a symmetrical C4-acid of the citric acid cycle as their precursor. This metabolite is most unusual in that an oxygenated methionine-derived carbon atom provides the growing point of a new carbon chain. A possible mechanism for the attachment of the lactone is suggested.

PATHWAYS OF CARBOHYDRATE METABOLISM IN LOBSTER HEPATOPANCREAS

1962 ◽  
Vol 40 (8) ◽  
pp. 1043-1050 ◽  
Author(s):  
P. W. Hochachka ◽  
J. M. Teal ◽  
M. Telford
Keyword(s):  
Citric Acid ◽  
Oxygen Uptake ◽  
Carbohydrate Metabolism ◽  
Citric Acid Cycle ◽  
The Other ◽  
Short Term ◽  
Acid Cycle

Oxygen uptake by homogenates of lobster hepatopancreas was stimulated by the addition of Embden–Meyerhof, pentose cycle, and citric acid cycle intermediates as well as xylose. Acetate-1-C14oxidation was blocked by fluoracetate and glucose-1-C14oxidation fell by 80% with iodoacetate treatment. TPN and DPN increased glucose-1-C14oxidation by 140% and 20% and acetate-1-C14oxidation by 50% and 100% respectively. Large amounts of C14enter polysaccharide following treatment with glucose-1-C14or acetate-1-C14but very little enters after treatment with the same amount of gluconate-1-C14. Gluconate and xylose oxidation occurs in mitochondria-free preparations. In short-term tests with acetate-1-C14as substrate, most of the label in glycogen is on carbons 3 and 4 and the amount in the other positions can be explained on the basis of a 5–10% participation of the pentose cycle.

Citric acid cycle in certain alterations of acid-base balance in human subjects

1961 ◽  
Vol 16 (4) ◽  
pp. 593-596 ◽  
Author(s):  
Wilbert Gamble ◽  
James M. Orten ◽  
Arthur H. Smith
Keyword(s):  
Citric Acid ◽  
Urinary Excretion ◽  
Citric Acid Cycle ◽  
Human Subjects ◽  
Statistical Significance ◽  
The Other ◽  
Acid Base Balance ◽  
Acid Base ◽  
Acid Cycle ◽  
Base Balance

An accurate chromatographic (silica gel) procedure for the quantitative measurement of the stable citric acid cycle acids and certain noncycle acids in urine was developed. The identity of the isolated acids was verified by paper chromatography. The method was applied to a study of urinary excretion of the cycle and other acids during certain alterations in acid-base balance in eight normal subjects, and one diabetic patient. During a “basic” regimen, the “alkaline tide,” and “respiratory alkalosis,” a significant increase in the excretion of citric acid occurred, with no significant change in that of the other cycle and noncycle acids. The “acidic” regimen produced a uniform decrease in the excretion of citrate to values approaching statistical significance; there was no consistent alteration in the excretion of the other acids. A similar decrease in the excretion of citric acid was observed in the patient during diabetic acidosis. It is concluded that of the Krebs cycle and other acids studied, the urinary excretion of only citric acid varies with alterations in acid-base balance. Submitted on February 10, 1961

PATHWAYS OF CARBOHYDRATE METABOLISM IN LOBSTER HEPATOPANCREAS

1962 ◽  
Vol 40 (1) ◽  
pp. 1043-1050 ◽  
Author(s):  
P. W. Hochachka ◽  
J. M. Teal ◽  
M. Telford
Keyword(s):  
Citric Acid ◽  
Oxygen Uptake ◽  
Carbohydrate Metabolism ◽  
Citric Acid Cycle ◽  
The Other ◽  
Short Term ◽  
Acid Cycle

Oxygen uptake by homogenates of lobster hepatopancreas was stimulated by the addition of Embden–Meyerhof, pentose cycle, and citric acid cycle intermediates as well as xylose. Acetate-1-C14oxidation was blocked by fluoracetate and glucose-1-C14oxidation fell by 80% with iodoacetate treatment. TPN and DPN increased glucose-1-C14oxidation by 140% and 20% and acetate-1-C14oxidation by 50% and 100% respectively. Large amounts of C14enter polysaccharide following treatment with glucose-1-C14or acetate-1-C14but very little enters after treatment with the same amount of gluconate-1-C14. Gluconate and xylose oxidation occurs in mitochondria-free preparations. In short-term tests with acetate-1-C14as substrate, most of the label in glycogen is on carbons 3 and 4 and the amount in the other positions can be explained on the basis of a 5–10% participation of the pentose cycle.

scholarly journals THE QUANTITATIVE HISTOCHEMISTRY OF THE SYMPATHOADRENAL SYSTEM II. ENZYMES OF THE CITRIC ACID, PENTOSE PHOSPHATE AND GLYCOGENOLYTIC PATHWAYS

1973 ◽  
Vol 21 (5) ◽  
pp. 483-487
Author(s):  
JAMES S. NELSON
Keyword(s):  
Citric Acid ◽  
Pentose Phosphate Pathway ◽  
Sympathetic Ganglion ◽  
Citric Acid Cycle ◽  
Sympathetic Neurons ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
Pentose Phosphate ◽  
The Other ◽  
Acid Cycle ◽  
Neuronal Groups

The activities of enzymes from the citric acid cycle, pentose phosphate pathway and glycogen cycle were measured in collections of sympathoadrenal cells and compared with other neuronal groups. Enzymes from each pathway are found in groups of sympathetic neurons and adrenal medullary cells. The citric acid cycle has the highest capacity among glucose pathways in sympathoadrenal cells. Differences in glycolytic and citric acid cycle capacities between sympathetic ganglion and the other neuronal groups may be related to differences in capillary density. The capacity of the pentose phosphate pathway and reduced nicotinamide adenine dinucleotide phosphate-linked isocitric dehydrogenase is higher in sympathoadrenal cells than in the other cells surveyed. The enzyme activities in sympathetic ganglion are in excess of those needed to sustain the rates of glucose metabolism previously observed in this structure.

EFFECT OF SERUM GONADOTROPHIN ON DEHYDROGENASES OF THE CITRIC ACID CYCLE IN THE OVARY OF THE RAT

1963 ◽  
Vol 42 (4) ◽  
pp. 480-484 ◽  
Author(s):  
B. Eckstein ◽  
R. Landsberg
Keyword(s):  
Citric Acid ◽  
Citric Acid Cycle ◽  
Age Groups ◽  
Succinic Dehydrogenase ◽  
Immature Rat ◽  
Acid Cycle ◽  
Immature Rats ◽  
Rat Ovary

ABSTRACT The succinic, malic and isocitric dehydrogenases in the ovary of immature and mature, normal and serum gonadotrophin injected rats were examined. The Qo2 of these enzymes were markedly enhanced in the gonadotrophin injected rats of both age groups, except in the case of succinic dehydrogenase in the ovary of the immature rats, where a slight non-significant decrease was noted. It is concluded that in the mature rat ovary, gonadotrophin administration stimulates the activity of all the examined dehydrogenases of the citric acid cycle, whereas in the immature rat ovary, at least the isocitric- and malic dehydrogenases are thus stimulated.

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