Fatty acid elongation by the microsomal fraction from germinating pea (Pisum sativum L.)

1980 ◽  
Vol 8 (1) ◽  
pp. 120-121
Author(s):  
BRIAN R. JORDAN ◽  
JOHN L. HARWOOD
1985 ◽  
Vol 225 (1) ◽  
pp. 267-270 ◽  
Author(s):  
D J Murphy ◽  
I E Woodrow ◽  
K D Mukherjee

In the microsomal fraction from young pea (Pisum sativum L.) leaves, the oleoyl moieties from oleoyl-CoA are principally transferred to the sn-2 position of phosphatidylcholine by oleoyl-CoA:1-acyl-lysophosphatidylcholine acyltransferase. The major product of this acyl transfer is 1-palmitoyl(stearoyl)-2-oleoyl phosphatidylcholine. The 1-palmitoyl(stearoyl)-2-oleoyl phosphatidylcholine is subsequently converted into 1-palmitoyl(stearoyl)-2-linoleoyl phosphatidylcholine by the oleate desaturase complex without equilibrating with the bulk membrane phosphatidylcholine pool. Hence, both the acyl transfer to phosphatidylcholine and the subsequent desaturation of oleoyl moieties occur on the sn-2 position of phosphatidylcholine, and there is also a functional coupling of the acyltransferase and oleate desaturase.


1982 ◽  
Vol 204 (2) ◽  
pp. 463-470 ◽  
Author(s):  
J Sanchez ◽  
B R Jordan ◽  
J Kay ◽  
J L Harwood

1. The effect of exogenous lipases on fatty acid synthesis from [14C]malonyl-CoA by the microsomal and soluble fractions from germinating peas was studied. 2. Addition of phospholipase A2 or the lipase from Rhizopus arrhizus had no effect on total fatty acid synthesis by the soluble fraction but caused severe inhibition of that by the microsomal fraction. 3. The addition of enzymes with phospholipase activity particularly inhibited the microsomal stearate elongase. 4. Control studies indicated that the phospholipase-induced inhibition of fatty acid synthesis was due to the location of fatty acid synthetase, palmitate elongase and stearate elongase on the outside of the microsomal vesicles. 5. Experiments with a trypsin-like proteinase showed that approximately half the microsomal fatty acid synthesis was resistant to proteolysis. 6. Although addition of exogenous phospholipases had no effect on total fatty acid synthesis by the soluble fraction, it did increase alpha-hydroxylation of newly-formed palmitate and stearate. 7. The results provide further evidence for differences between the soluble and particulate fatty acid synthetase and palmitate elongase activities of germinating pea.


1986 ◽  
Vol 240 (3) ◽  
pp. 837-842 ◽  
Author(s):  
M J Price-Jones ◽  
J L Harwood

Several possible control mechanisms for CTP:choline-phosphate cytidylyltransferase (EC 2.7.7.15) activity in pea (Pisum sativum L.) stems were investigated. Indol-3-ylacetic acid (IAA) treatment of the pea stems decreased total cytidylyltransferase activity but did not affect its subcellular distribution. Oleate (2 mM) caused some stimulation of enzyme activity by release of activity from the microsomal fraction into the cytosol, but neither phosphatidylglycerol nor monoacyl phosphatidylethanolamine had an effect on activity or subcellular distribution. A decrease in soluble cytidylyltransferase protein concentrations was found in IAA-treated pea stems, but this was not sufficient to account for all of the decrease in cytidylyltransferase activity. A 50% inhibition of enzyme activity could be obtained with 0.2 mM-CMP, which indicated possible allosteric regulation. Similar inhibition was obtained with 1.5 mM-ATP, but other nucleotides had no effect. The cytidylyltransferase enzyme protein was not directly phosphorylated, and the inhibition with 1.5 mM-ATP occurred with the purified enzyme, thus excluding an obligatory mediation via a modulator protein. The results indicate that the cytosolic form of cytidylyltransferase is the most important in pea stem tissue and that the decrease in cytidylyltransferase activity in IAA-treated material appears to be brought about by several methods.


2012 ◽  
Vol 102 (2-3) ◽  
pp. 142-150 ◽  
Author(s):  
Manuela Renna ◽  
Paolo Cornale ◽  
Carola Lussiana ◽  
Vanda Malfatto ◽  
Riccardo Fortina ◽  
...  

1977 ◽  
Vol 5 (1) ◽  
pp. 287-289 ◽  
Author(s):  
JOHN L. HARWOOD ◽  
PAUL BOLTON

2007 ◽  
Vol 84 (11) ◽  
pp. 1031-1038 ◽  
Author(s):  
Hiromi Yoshida ◽  
Yuka Tomiyama ◽  
Masayuki Saiki ◽  
Yoshiyuki Mizushina

1983 ◽  
Vol 213 (1) ◽  
pp. 249-252 ◽  
Author(s):  
D J Murphy ◽  
K D Mukherjee ◽  
E Latzko

On incubation of microsomal fraction from pea (Pisum sativum L.) leaves with ammonium [1-14C]oleate or [1-14C]oleoyl-CoA in the presence of ATP, CoA, Mg2+ and NADH, the major reactions observed were those catalysed by oleoyl-CoA synthetase, oleoyl-CoA thioesterase, oleoyl-CoA:phosphatidylcholine acyltransferase and oleoyl phosphatidylcholine desaturase. The reaction catalysed by oleoyl phosphatidylcholine desaturase was specifically inhibited by H2O2, and this inhibitory effect was overcome by catalase (EC 1.11.1.6).


2018 ◽  
Vol 34 (2) ◽  
pp. 229-235 ◽  
Author(s):  
Prachi Garg ◽  
◽  
A. Hemantaranjan ◽  
Jyostnarani Pradhan ◽  
◽  
...  

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