Rates of Oxidation of the Methionine and S-Adenosylmethionine Methyl Carbons in Isolated Rat Hepatocytes
The methyl group of methionine (Met) is metabolized via activation to S-adenosylmethionine (AdoMet) and subsequent transmethylation and also by a transamination-decarboxylation route. To estimate the contribution of pathways independent of AdoMet formation in the oxidation of physiological levels of...
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| Veröffentlicht in: | The Journal of nutrition 1987-11, Vol.117 (11), p.1820-1826 |
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| container_title | The Journal of nutrition |
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| creator | Engstrom, Mark A. Benevenga, Norlin J. |
| description | The methyl group of methionine (Met) is metabolized via activation to S-adenosylmethionine (AdoMet) and subsequent transmethylation and also by a transamination-decarboxylation route. To estimate the contribution of pathways independent of AdoMet formation in the oxidation of physiological levels of Met to CO2, the oxidation rates of L-[methyl-14C]Met and L-[methyl-14C]AdoMet were compared in hepatocyte suspensions. Hepatocytes took up AdoMet from the medium and oxidized its methyl group to CO2 at a rate of 280 ± 22 nmol/g wet cells per hour, which was constant at extracellular concentrations between 0.1 and 1.0 mM AdoMet and Met. Hepatocytes took up L-[methyl-14C]Met and reached an intracellular specific activity within 10 min that was |
| doi_str_mv | 10.1093/jn/117.11.1820 |
| format | Article |
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To estimate the contribution of pathways independent of AdoMet formation in the oxidation of physiological levels of Met to CO2, the oxidation rates of L-[methyl-14C]Met and L-[methyl-14C]AdoMet were compared in hepatocyte suspensions. Hepatocytes took up AdoMet from the medium and oxidized its methyl group to CO2 at a rate of 280 ± 22 nmol/g wet cells per hour, which was constant at extracellular concentrations between 0.1 and 1.0 mM AdoMet and Met. Hepatocytes took up L-[methyl-14C]Met and reached an intracellular specific activity within 10 min that was <10% of the specific activity in the medium at 0.1 mM Met and 20–30% at 1.0 mM Met. In contrast, L-[methyl-14C]AdoMet formed from L-[methyl-14C]Met reached a specific activity that was 40–50% (0.1 mM Met) and 50–60% (1.0 mM Met) of the specific activity of Met in the medium. These results suggest that AdoMet is formed from a mixture of extracellular and intracellular Met. If the specific activity of AdoMet represents the pool from which Met is oxidized, then the oxidation rates of Met methyl were 1200 and 1859 nmol/(g·h) at 0.1 and 1.0 mM Met, respectively. Thus, oxidation of Met via AdoMet formation accounts for only 12% (at 1 mM Met) to 21% (at 0.1 mM Met) of the total in rat hepatocytes. Pretreatment with high levels of dietary Met caused adaptive increases in both AdoMet and Met methyl oxidation rates.</description><identifier>ISSN: 0022-3166</identifier><identifier>EISSN: 1541-6100</identifier><identifier>DOI: 10.1093/jn/117.11.1820</identifier><identifier>PMID: 3119797</identifier><identifier>CODEN: JONUAI</identifier><language>eng</language><publisher>Bethesda, MD: Elsevier Inc</publisher><subject>Animals ; Biological and medical sciences ; Carbon Dioxide - metabolism ; CELLS ; CELLULE ; CELULAS ; EXPERIMENTACION IN VITRO ; EXPERIMENTATION IN VITRO ; FOIE ; Fundamental and applied biological sciences. Psychology ; hepatocytes ; HIGADO ; IN VITRO EXPERIMENTATION ; Kinetics ; LIVER ; Liver - metabolism ; Liver. Bile. Biliary tracts ; Male ; METABOLISM ; METABOLISME ; METABOLISMO ; METHIONINE ; Methionine - metabolism ; Methylation ; METIONINA ; Oxidation-Reduction ; RAT ; RATA ; RATS ; S-adenosylmethionine ; S-Adenosylmethionine - metabolism ; Vertebrates: digestive system</subject><ispartof>The Journal of nutrition, 1987-11, Vol.117 (11), p.1820-1826</ispartof><rights>1987 American Society for Nutrition.</rights><rights>1988 INIST-CNRS</rights><lds50>peer_reviewed</lds50><oa>free_for_read</oa><woscitedreferencessubscribed>false</woscitedreferencessubscribed><citedby>FETCH-LOGICAL-c361t-2bc7b9dd5c425393ca108fe80ed6ed674be2f695638ee0dfcfb08109a4ab367e3</citedby><cites>FETCH-LOGICAL-c361t-2bc7b9dd5c425393ca108fe80ed6ed674be2f695638ee0dfcfb08109a4ab367e3</cites></display><links><openurl>$$Topenurl_article</openurl><openurlfulltext>$$Topenurlfull_article</openurlfulltext><thumbnail>$$Tsyndetics_thumb_exl</thumbnail><link.rule.ids>314,780,784,27924,27925</link.rule.ids><backlink>$$Uhttp://pascal-francis.inist.fr/vibad/index.php?action=getRecordDetail&idt=7596876$$DView record in Pascal Francis$$Hfree_for_read</backlink><backlink>$$Uhttps://www.ncbi.nlm.nih.gov/pubmed/3119797$$D View this record in MEDLINE/PubMed$$Hfree_for_read</backlink></links><search><creatorcontrib>Engstrom, Mark A.</creatorcontrib><creatorcontrib>Benevenga, Norlin J.</creatorcontrib><title>Rates of Oxidation of the Methionine and S-Adenosylmethionine Methyl Carbons in Isolated Rat Hepatocytes</title><title>The Journal of nutrition</title><addtitle>J Nutr</addtitle><description>The methyl group of methionine (Met) is metabolized via activation to S-adenosylmethionine (AdoMet) and subsequent transmethylation and also by a transamination-decarboxylation route. To estimate the contribution of pathways independent of AdoMet formation in the oxidation of physiological levels of Met to CO2, the oxidation rates of L-[methyl-14C]Met and L-[methyl-14C]AdoMet were compared in hepatocyte suspensions. Hepatocytes took up AdoMet from the medium and oxidized its methyl group to CO2 at a rate of 280 ± 22 nmol/g wet cells per hour, which was constant at extracellular concentrations between 0.1 and 1.0 mM AdoMet and Met. Hepatocytes took up L-[methyl-14C]Met and reached an intracellular specific activity within 10 min that was <10% of the specific activity in the medium at 0.1 mM Met and 20–30% at 1.0 mM Met. In contrast, L-[methyl-14C]AdoMet formed from L-[methyl-14C]Met reached a specific activity that was 40–50% (0.1 mM Met) and 50–60% (1.0 mM Met) of the specific activity of Met in the medium. These results suggest that AdoMet is formed from a mixture of extracellular and intracellular Met. If the specific activity of AdoMet represents the pool from which Met is oxidized, then the oxidation rates of Met methyl were 1200 and 1859 nmol/(g·h) at 0.1 and 1.0 mM Met, respectively. Thus, oxidation of Met via AdoMet formation accounts for only 12% (at 1 mM Met) to 21% (at 0.1 mM Met) of the total in rat hepatocytes. Pretreatment with high levels of dietary Met caused adaptive increases in both AdoMet and Met methyl oxidation rates.</description><subject>Animals</subject><subject>Biological and medical sciences</subject><subject>Carbon Dioxide - metabolism</subject><subject>CELLS</subject><subject>CELLULE</subject><subject>CELULAS</subject><subject>EXPERIMENTACION IN VITRO</subject><subject>EXPERIMENTATION IN VITRO</subject><subject>FOIE</subject><subject>Fundamental and applied biological sciences. Psychology</subject><subject>hepatocytes</subject><subject>HIGADO</subject><subject>IN VITRO EXPERIMENTATION</subject><subject>Kinetics</subject><subject>LIVER</subject><subject>Liver - metabolism</subject><subject>Liver. Bile. Biliary tracts</subject><subject>Male</subject><subject>METABOLISM</subject><subject>METABOLISME</subject><subject>METABOLISMO</subject><subject>METHIONINE</subject><subject>Methionine - metabolism</subject><subject>Methylation</subject><subject>METIONINA</subject><subject>Oxidation-Reduction</subject><subject>RAT</subject><subject>RATA</subject><subject>RATS</subject><subject>S-adenosylmethionine</subject><subject>S-Adenosylmethionine - metabolism</subject><subject>Vertebrates: digestive system</subject><issn>0022-3166</issn><issn>1541-6100</issn><fulltext>true</fulltext><rsrctype>article</rsrctype><creationdate>1987</creationdate><recordtype>article</recordtype><sourceid>EIF</sourceid><recordid>eNp1kM9rFDEYhoModa1ePSnkIN5mm2-ykx_HsqgtVArWnkMm-cbNMpusyWxx_3sz7FJPQkL4eJ-8CQ8h74EtgWl-tY1XAHIJsATVshdkAd0KGgGMvSQLxtq24SDEa_KmlC1jDFZaXZALDqCllguy-WEnLDQN9P5P8HYKKc7DtEH6HadNHUNEaqOnD821x5jKcdz9C2bmONK1zX2KhYZIb0saa6WntZje4N5OyR3rE2_Jq8GOBd-dz0vy-PXLz_VNc3f_7XZ9fdc4LmBq2t7JXnvfuVXbcc2dBaYGVAy9qEuuemwHoTvBFSLzgxt6pqoIu7I9FxL5Jfl86t3n9PuAZTK7UByOo42YDsVIqXgnhKrg8gS6nErJOJh9DjubjwaYmdWabTRVbd1mVlsvfDw3H_od-mf87LLmn865Lc6OQ7bRhfKMyU4LJUXFPpywwSZjf-WKPD4oBdBpreZvqVOMVdJTwGyKCxgd-pDRTcan8L8P_gWaXZ21</recordid><startdate>19871101</startdate><enddate>19871101</enddate><creator>Engstrom, Mark A.</creator><creator>Benevenga, Norlin J.</creator><general>Elsevier Inc</general><general>American Society for Nutritional Sciences</general><scope>FBQ</scope><scope>IQODW</scope><scope>CGR</scope><scope>CUY</scope><scope>CVF</scope><scope>ECM</scope><scope>EIF</scope><scope>NPM</scope><scope>AAYXX</scope><scope>CITATION</scope><scope>7X8</scope></search><sort><creationdate>19871101</creationdate><title>Rates of Oxidation of the Methionine and S-Adenosylmethionine Methyl Carbons in Isolated Rat Hepatocytes</title><author>Engstrom, Mark A. ; Benevenga, Norlin J.</author></sort><facets><frbrtype>5</frbrtype><frbrgroupid>cdi_FETCH-LOGICAL-c361t-2bc7b9dd5c425393ca108fe80ed6ed674be2f695638ee0dfcfb08109a4ab367e3</frbrgroupid><rsrctype>articles</rsrctype><prefilter>articles</prefilter><language>eng</language><creationdate>1987</creationdate><topic>Animals</topic><topic>Biological and medical sciences</topic><topic>Carbon Dioxide - metabolism</topic><topic>CELLS</topic><topic>CELLULE</topic><topic>CELULAS</topic><topic>EXPERIMENTACION IN VITRO</topic><topic>EXPERIMENTATION IN VITRO</topic><topic>FOIE</topic><topic>Fundamental and applied biological sciences. Psychology</topic><topic>hepatocytes</topic><topic>HIGADO</topic><topic>IN VITRO EXPERIMENTATION</topic><topic>Kinetics</topic><topic>LIVER</topic><topic>Liver - metabolism</topic><topic>Liver. Bile. Biliary tracts</topic><topic>Male</topic><topic>METABOLISM</topic><topic>METABOLISME</topic><topic>METABOLISMO</topic><topic>METHIONINE</topic><topic>Methionine - metabolism</topic><topic>Methylation</topic><topic>METIONINA</topic><topic>Oxidation-Reduction</topic><topic>RAT</topic><topic>RATA</topic><topic>RATS</topic><topic>S-adenosylmethionine</topic><topic>S-Adenosylmethionine - metabolism</topic><topic>Vertebrates: digestive system</topic><toplevel>peer_reviewed</toplevel><toplevel>online_resources</toplevel><creatorcontrib>Engstrom, Mark A.</creatorcontrib><creatorcontrib>Benevenga, Norlin J.</creatorcontrib><collection>AGRIS</collection><collection>Pascal-Francis</collection><collection>Medline</collection><collection>MEDLINE</collection><collection>MEDLINE (Ovid)</collection><collection>MEDLINE</collection><collection>MEDLINE</collection><collection>PubMed</collection><collection>CrossRef</collection><collection>MEDLINE - Academic</collection><jtitle>The Journal of nutrition</jtitle></facets><delivery><delcategory>Remote Search Resource</delcategory><fulltext>fulltext</fulltext></delivery><addata><au>Engstrom, Mark A.</au><au>Benevenga, Norlin J.</au><format>journal</format><genre>article</genre><ristype>JOUR</ristype><atitle>Rates of Oxidation of the Methionine and S-Adenosylmethionine Methyl Carbons in Isolated Rat Hepatocytes</atitle><jtitle>The Journal of nutrition</jtitle><addtitle>J Nutr</addtitle><date>1987-11-01</date><risdate>1987</risdate><volume>117</volume><issue>11</issue><spage>1820</spage><epage>1826</epage><pages>1820-1826</pages><issn>0022-3166</issn><eissn>1541-6100</eissn><coden>JONUAI</coden><abstract>The methyl group of methionine (Met) is metabolized via activation to S-adenosylmethionine (AdoMet) and subsequent transmethylation and also by a transamination-decarboxylation route. To estimate the contribution of pathways independent of AdoMet formation in the oxidation of physiological levels of Met to CO2, the oxidation rates of L-[methyl-14C]Met and L-[methyl-14C]AdoMet were compared in hepatocyte suspensions. Hepatocytes took up AdoMet from the medium and oxidized its methyl group to CO2 at a rate of 280 ± 22 nmol/g wet cells per hour, which was constant at extracellular concentrations between 0.1 and 1.0 mM AdoMet and Met. Hepatocytes took up L-[methyl-14C]Met and reached an intracellular specific activity within 10 min that was <10% of the specific activity in the medium at 0.1 mM Met and 20–30% at 1.0 mM Met. In contrast, L-[methyl-14C]AdoMet formed from L-[methyl-14C]Met reached a specific activity that was 40–50% (0.1 mM Met) and 50–60% (1.0 mM Met) of the specific activity of Met in the medium. These results suggest that AdoMet is formed from a mixture of extracellular and intracellular Met. If the specific activity of AdoMet represents the pool from which Met is oxidized, then the oxidation rates of Met methyl were 1200 and 1859 nmol/(g·h) at 0.1 and 1.0 mM Met, respectively. Thus, oxidation of Met via AdoMet formation accounts for only 12% (at 1 mM Met) to 21% (at 0.1 mM Met) of the total in rat hepatocytes. Pretreatment with high levels of dietary Met caused adaptive increases in both AdoMet and Met methyl oxidation rates.</abstract><cop>Bethesda, MD</cop><pub>Elsevier Inc</pub><pmid>3119797</pmid><doi>10.1093/jn/117.11.1820</doi><tpages>7</tpages><oa>free_for_read</oa></addata></record> |
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| subjects | Animals Biological and medical sciences Carbon Dioxide - metabolism CELLS CELLULE CELULAS EXPERIMENTACION IN VITRO EXPERIMENTATION IN VITRO FOIE Fundamental and applied biological sciences. Psychology hepatocytes HIGADO IN VITRO EXPERIMENTATION Kinetics LIVER Liver - metabolism Liver. Bile. Biliary tracts Male METABOLISM METABOLISME METABOLISMO METHIONINE Methionine - metabolism Methylation METIONINA Oxidation-Reduction RAT RATA RATS S-adenosylmethionine S-Adenosylmethionine - metabolism Vertebrates: digestive system |
| title | Rates of Oxidation of the Methionine and S-Adenosylmethionine Methyl Carbons in Isolated Rat Hepatocytes |
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