Vacuolar chain elongation of raffinose oligosaccharides in Ajuga reptans

2000 ◽  
Vol 27 (9) ◽  
pp. 743 ◽  
Author(s):  
Renate Braun ◽  
Felix Keller
Keyword(s):  
Osmotic Shock ◽  
Subcellular Location ◽  
Assimilate Transport ◽  
Chain Elongation ◽  
Raffinose Family Oligosaccharides ◽  
Raffinose Oligosaccharides ◽  
Ajuga Reptans ◽  
Key Enzyme ◽  
Autumn And Winter ◽  
Long Chain

This paper originates from a presentation at the International Conference on Assimilate Transport and Partitioning, Newcastle, NSW, August 1999 Galactan : galactan galactosyltransferase (GGT) is the key enzyme responsible for the accumulation of long-chain raffinose family oligosaccharides (RFOs; α-D-galn(1,6) α-D-glc(1,2) β-D-fru) in Ajuga reptans L. leaves during autumn and winter. The exact subcellular location of GGT is not known and its elucidation was the aim of this paper. A method for the isolation of vacuoles from A. reptans mesophyll protoplasts was developed using a pH and osmotic shock to rupture the plasma membrane selectively. By comparing protoplasts with vacuoles, GGT was confirmed to be a vacuolar enzyme. By comparing vacuoles with tonoplast vesicles and cell sap fractions, GGT was further shown to reside in the cell sap and not in the tonoplast. These findings suggest the need for a tonoplast-bound mechanism for the transport of short-chain RFOs such as stachyose or raffinose into the vacuole for subsequent chain elongation.

In vivo study of the biosynthesis of long-chain fatty acids using deuterated water

1995 ◽  
Vol 269 (2) ◽  
pp. E247-E252 ◽  
Author(s):  
H. O. Ajie ◽  
M. J. Connor ◽  
W. N. Lee ◽  
S. Bassilian ◽  
E. A. Bergner ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
De Novo ◽  
Chain Elongation ◽  
Deuterated Water ◽  
De Novo Synthesis ◽  
Isotopomer Distribution ◽  
Long Chain ◽  
Mass Isotopomer

To determine the contributions of preexisting fatty acid, de novo synthesis, and chain elongation in long-chain fatty acid (LCFA) synthesis, the synthesis of LCFAs, palmitate (16:0), stearate (18:0), arachidate (20:0), behenate (22:0), and lignocerate (24:0), in the epidermis, liver, and spinal cord was determined using deuterated water and mass isotopomer distribution analysis in hairless mice and Sprague-Dawley rats. Animals were given 4% deuterated water for 5 days or 8 wk in their drinking water. Blood was withdrawn at the end of these times for the determination of deuterium enrichment, and the animals were killed to isolate the various tissues for lipid extraction for the determination of the mass isotopomer distributions. The mass isotopomer distributions in LCFA were incompatible with synthesis from a single pool of primer. The synthesis of palmitate, stearate, arachidate, behenate, and lignocerate followed the expected biochemical pathways for the synthesis of LCFAs. On average, three deuterium atoms were incorporated for every addition of an acetyl unit. The isotopomer distribution resulting from chain elongation and de novo synthesis can be described by the linear combination of two binomial distributions. The proportions of preexisting, chain elongation, and de novo-synthesized fatty acids as a percentage of the total fatty acids were determined using multiple linear regression analysis. Fractional synthesis was found to vary, depending on the tissue type and the fatty acid, from 47 to 87%. A substantial fraction (24-40%) of the newly synthesized molecules was derived from chain elongation of unlabeled (recycled) palmitate.

scholarly journals The synthesis and hydrolysis of long-chain fatty acyl-coenzyme A thioesters by soluble and microsomal fractions from the brain of the developing rat

1976 ◽  
Vol 160 (2) ◽  
pp. 247-251 ◽  
Author(s):  
P J Brophy ◽  
D E Vance
Keyword(s):  
Fatty Acid ◽  
Microsomal Fraction ◽  
Specific Activity ◽  
Arachidic Acid ◽  
Fatty Acyl ◽  
Chain Elongation ◽  
Fatty Acid Chain ◽  
Specific Activities ◽  
Coa Hydrolase ◽  
Long Chain

1. The specific activities of long-chain fatty acid-CoA ligase (EC6.2.1.3) and of long-chain fatty acyl-CoA hydrolase (EC3.1.2.2) were measured in soluble and microsomal fractions from rat brain. 2. In the presence of either palmitic acid or stearic acid, the specific activity of the ligase increased during development; the specific activity of this enzyme with arachidic acid or behenic acid was considerably lower. 3. The specific activities of palmitoyl-CoA hydrolase and of stearoyl-CoA hydrolase in the microsomal fraction decreased markedly (75%) between 6 and 20 days after birth; by contrast, the corresponding specific activities in the soluble fraction showed no decline. 4. Stearoyl-CoA hydrolase in the microsomal fraction is inhibited (99%) by bovine serum albumin; this is in contrast with the microsomal fatty acid-chain-elongation system, which is stimulated 3.9-fold by albumin. Inhibition of stearoyl-CoA hydrolase does not stimulate stearoyl-CoA chain elongation. Therefore it does not appear likely that the decline in the specific activity of hydrolase during myelogenesis is responsible for the increased rate of fatty acid chain elongation. 5. It is suggested that the decline in specific activity of the microsomal hydrolase and to a lesser extent the increase in the specific activity of the ligase is directly related to the increased demand for long-chain acyl-CoA esters during myelogenesis as substrates in the biosynthesis of myelin lipids.

Efficient Asymmetric Synthesis of Long-Chain Polyketides Containing up to Ten Contiguous Stereogenic Centres by Double Chain Elongation

2011 ◽  
Vol 2011 (18) ◽  
pp. 3317-3328 ◽  
Author(s):  
Maris Turks ◽  
Kelly A. Fairweather ◽  
Rosario Scopelliti ◽  
Pierre Vogel
Keyword(s):  
Asymmetric Synthesis ◽  
Chain Elongation ◽  
Double Chain ◽  
Long Chain

scholarly journals Soybean seed galactinol synthase activity as determined by a novel colorimetric assay

2000 ◽  
Vol 12 (3) ◽  
pp. 203-212 ◽  
Author(s):  
MARLUCI RIBEIRO ◽  
CARLOS R. FELIX ◽  
SILENE DE PAULINO LOZZI
Keyword(s):  
Colorimetric Assay ◽  
Colorimetric Method ◽  
Soybean Seed ◽  
Maximum Activity ◽  
Soybean Seeds ◽  
Colorimetric Determination ◽  
Raffinose Oligosaccharides ◽  
Galactinol Synthase ◽  
Isotopic Method ◽  
Key Enzyme

Galactinol synthase (GS) is a key enzyme for the biosynthesis of raffinose oligosaccharides (RO) which are the flatulence factors present in soybean seeds and several other legumes. Understanding of soybean seed GS properties is, therefore, of biotechnological interest. The GS enzyme catalyses formation of galactinol and UDP from UDP-gal and myo-inositol. This enzyme is currently assayed by an isotopic method. We have then idealized a more convenient method for GS assay based on the indirect colorimetric determination of the UDP formed which is then hydrolyzed by exogenous apyrase and the resulting Pi quantified by a modification of the colorimetric method of Fiske & SubbaRow. The color developed is stable, and the method is suitable for detection of very low GS activity. The GS activity profiles of developing soybean seeds determined by the isotopic and the colorimetric methods are closely related. The GS enzyme was partially purified (46-fold) by treatment of seed extract with MnCl2, sequential chromatographies on DEAE-Sepharose, Phenyl-Sepharose CL-4B and Q-Sepharose columns. The crude and the partially purified enzyme showed maximum activity at pH 7.0 and 50 ºC. Dithiothreitol and MnCl2 enhanced considerably the activity of the partially purified enzyme. While UDP-glc could be hydrolyzed by the enzyme at a reative activity corresponding to 49% of that calculated for UDP-gal, UDP-man and sucrose were completely ineffective as alternative substrates.

Fatty Acids: Evolution in Relation to Neurobiology

1993 ◽  
Vol 71 (9) ◽  
pp. 683-683 ◽  
Author(s):  
M. T. Clandinin
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Polyunsaturated Fatty Acids ◽  
Acid Content ◽  
Essential Fatty Acids ◽  
Fatty Acid Content ◽  
Chain Elongation ◽  
Brain Membrane ◽  
The Impact ◽  
Long Chain

Metabolism of long-chain polyunsaturated fatty acids derived from 18:2ω−6 and 18:3ω−3 by chain elongation – desaturation is essential for synthesis of complex structural lipids, leukotrienes, thromboxanes, and prostaglandins. These essential fatty acids are required for normal function in developing tissues and appropriate maturation of a wide variety of physiological processes. During development, fetal accretion of long-chain metabolites of ω−6 and ω−3 fatty acids may result from maternal or placental synthesis and transfer or, alternatively, from the metabolism of 18:2ω−6 and 18:3ω−3 to longer chain homologues by the fetus. After birth the infant must synthesize or be fed the very long chain polyunsaturated fatty acids of C20 and C22 type derived from 18:2ω−6 and 18:3ω−3.Metabolism of ω−6 and ω−3 fatty acids utilizes the same enzyme system and is competitive. When levels of dietary ω−3 and ω−6 C18 fatty acids are altered, the levels of metabolites of these precursor fatty acids change in specific brain membranes, influencing membrane lipid dependent functions. For example, a diet unbalanced in very long chain ω−3 and ω−6 fatty acids may increase brain membrane ω−3 fatty acid content when 20:5ω−3 is fed, while decreasing membrane fatty acid content of the ω−6 series of competing fatty acids. As 20:4ω−6 is quantitatively and qualitatively important to brain phospholipid, significant reduction in brain levels of 20:4ω−6 may be less than optimal. The impact of these compositional changes on brain function is not yet clear.The authors in this symposium address how this general area of essential fatty acid metabolism is relevant to the evolution of man, growth and development of fish, function of the retina and neural tissue, cognitive development of infants, and infant nutrition.

Decrease of Ceramides with Long‐Chain Fatty Acids in Psoriasis: Possible Inhibitory Effect of Interferon Gamma on Chain Elongation

2021 ◽  
Author(s):  
Bo‐Kyung Kim ◽  
Jong Cheol Shon ◽  
Hee Seok Seo ◽  
Kwang‐Hyeon Liu ◽  
Jong Won Lee ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Interferon Gamma ◽  
Inhibitory Effect ◽  
Chain Elongation ◽  
Long Chain Fatty Acids ◽  
Long Chain ◽  
Chain Fatty Acids
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