Characterization of a Soluble Phosphatidic Acid Phosphatase in Bitter Melon (Momordica charantia)
Momordica charantia is often called bitter melon, bitter gourd or bitter squash because its fruit has a bitter taste. The fruit has been widely used as vegetable and herbal medicine. Alpha-eleostearic acid is the major fatty acid in the seeds, but little is known about its biosynthesis. As an initi...
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| Format: | Online |
| Language: | English |
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Public Library of Science
2014
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| Online Access: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4159287/ |
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pubmed-4159287 |
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pubmed-41592872014-09-12 Characterization of a Soluble Phosphatidic Acid Phosphatase in Bitter Melon (Momordica charantia) Cao, Heping Sethumadhavan, Kandan Grimm, Casey C. Ullah, Abul H. J. Research Article Momordica charantia is often called bitter melon, bitter gourd or bitter squash because its fruit has a bitter taste. The fruit has been widely used as vegetable and herbal medicine. Alpha-eleostearic acid is the major fatty acid in the seeds, but little is known about its biosynthesis. As an initial step towards understanding the biochemical mechanism of fatty acid accumulation in bitter melon seeds, this study focused on a soluble phosphatidic acid phosphatase (PAP, 3-sn-phosphatidate phosphohydrolase, EC 3.1.3.4) that hydrolyzes the phosphomonoester bond in phosphatidate yielding diacylglycerol and Pi. PAPs are typically categorized into two subfamilies: Mg2+-dependent soluble PAP and Mg2+-independent membrane-associated PAP. We report here the partial purification and characterization of an Mg2+-independent PAP activity from developing cotyledons of bitter melon. PAP protein was partially purified by successive centrifugation and UNOsphere Q and S columns from the soluble extract. PAP activity was optimized at pH 6.5 and 53–60°C and unaffected by up to 0.3 mM MgCl2. The Km and Vmax values for dioleoyl-phosphatidic acid were 595.4 µM and 104.9 ηkat/mg of protein, respectively. PAP activity was inhibited by NaF, Na3VO4, Triton X-100, FeSO4 and CuSO4, but stimulated by MnSO4, ZnSO4 and Co(NO3)2. In-gel activity assay and mass spectrometry showed that PAP activity was copurified with a number of other proteins. This study suggests that PAP protein is probably associated with other proteins in bitter melon seeds and that a new class of PAP exists as a soluble and Mg2+-independent enzyme in plants. Public Library of Science 2014-09-09 /pmc/articles/PMC4159287/ /pubmed/25203006 http://dx.doi.org/10.1371/journal.pone.0106403 Text en https://creativecommons.org/publicdomain/zero/1.0/ This is an open-access article distributed under the terms of the Creative Commons Public Domain declaration, which stipulates that, once placed in the public domain, this work may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. |
| repository_type |
Open Access Journal |
| institution_category |
Foreign Institution |
| institution |
US National Center for Biotechnology Information |
| building |
NCBI PubMed |
| collection |
Online Access |
| language |
English |
| format |
Online |
| author |
Cao, Heping Sethumadhavan, Kandan Grimm, Casey C. Ullah, Abul H. J. |
| spellingShingle |
Cao, Heping Sethumadhavan, Kandan Grimm, Casey C. Ullah, Abul H. J. Characterization of a Soluble Phosphatidic Acid Phosphatase in Bitter Melon (Momordica charantia) |
| author_facet |
Cao, Heping Sethumadhavan, Kandan Grimm, Casey C. Ullah, Abul H. J. |
| author_sort |
Cao, Heping |
| title |
Characterization of a Soluble Phosphatidic Acid Phosphatase in Bitter Melon (Momordica charantia) |
| title_short |
Characterization of a Soluble Phosphatidic Acid Phosphatase in Bitter Melon (Momordica charantia) |
| title_full |
Characterization of a Soluble Phosphatidic Acid Phosphatase in Bitter Melon (Momordica charantia) |
| title_fullStr |
Characterization of a Soluble Phosphatidic Acid Phosphatase in Bitter Melon (Momordica charantia) |
| title_full_unstemmed |
Characterization of a Soluble Phosphatidic Acid Phosphatase in Bitter Melon (Momordica charantia) |
| title_sort |
characterization of a soluble phosphatidic acid phosphatase in bitter melon (momordica charantia) |
| description |
Momordica charantia is often called bitter melon, bitter gourd or bitter squash because its fruit has a bitter taste. The fruit has been widely used as vegetable and herbal medicine. Alpha-eleostearic acid is the major fatty acid in the seeds, but little is known about its biosynthesis. As an initial step towards understanding the biochemical mechanism of fatty acid accumulation in bitter melon seeds, this study focused on a soluble phosphatidic acid phosphatase (PAP, 3-sn-phosphatidate phosphohydrolase, EC 3.1.3.4) that hydrolyzes the phosphomonoester bond in phosphatidate yielding diacylglycerol and Pi. PAPs are typically categorized into two subfamilies: Mg2+-dependent soluble PAP and Mg2+-independent membrane-associated PAP. We report here the partial purification and characterization of an Mg2+-independent PAP activity from developing cotyledons of bitter melon. PAP protein was partially purified by successive centrifugation and UNOsphere Q and S columns from the soluble extract. PAP activity was optimized at pH 6.5 and 53–60°C and unaffected by up to 0.3 mM MgCl2. The Km and Vmax values for dioleoyl-phosphatidic acid were 595.4 µM and 104.9 ηkat/mg of protein, respectively. PAP activity was inhibited by NaF, Na3VO4, Triton X-100, FeSO4 and CuSO4, but stimulated by MnSO4, ZnSO4 and Co(NO3)2. In-gel activity assay and mass spectrometry showed that PAP activity was copurified with a number of other proteins. This study suggests that PAP protein is probably associated with other proteins in bitter melon seeds and that a new class of PAP exists as a soluble and Mg2+-independent enzyme in plants. |
| publisher |
Public Library of Science |
| publishDate |
2014 |
| url |
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4159287/ |
| _version_ |
1613132442482245632 |