Methionine supply to growing steers affects hepatic activities of methionine synthase and betaine-homocysteine methyltransferase, but not cystathionine synthase.

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  • Additional Information
    • Source:
      Publisher: Elsevier Country of Publication: United States NLM ID: 0404243 Publication Model: Print Cited Medium: Print ISSN: 0022-3166 (Print) Linking ISSN: 00223166 NLM ISO Abbreviation: J Nutr Subsets: MEDLINE
    • Publication Information:
      Publication: 2023- : [New York, NY] : Elsevier
      Original Publication: 1928-1933 : Springfield, Ill. : C. C. Thomas
    • Subject Terms:
      5-Methyltetrahydrofolate-Homocysteine S-Methyltransferase/*metabolism ; Aging/*metabolism ; Cystathionine beta-Synthase/*metabolism ; Liver/*enzymology ; Methionine/*pharmacology ; Methyltransferases/*metabolism; Amino Acids/blood ; Animals ; Betaine-Homocysteine S-Methyltransferase ; Cattle/growth & development ; Cattle/metabolism ; Male ; Nitrogen/metabolism ; Osmolar Concentration
    • Abstract:
      The effects of supplemental methionine (Met), supplied abomasally, on the activities of methionine synthase (MS), cystathionine synthase (CS) and betaine-homocysteine methyltransferase (BHMT) were studied in growing steers. Six Holstein steers (205 kg) were used in a replicated 3 x 3 Latin square experiment. Steers were fed 2.6 kg dry matter daily of a diet containing 83% soybean hulls and 8% wheat straw. Ruminal infusions of 180 g/d acetate, 180 g/d propionate, 45 g/d butyrate, and abomasal infusion of 300 g/d dextrose provided additional energy. An amino acid mixture (299 g/d) limiting in Met was infused into the abomasum to ensure that nonsulfur amino acids did not limit growth. Treatments were infused abomasally and included 0, 5 or 10 g/d L-Met. Retained N (20.5, 26.9 and 31.6 g/d for 0, 5 and 10 g/d L-Met, respectively) increased (P < 0.01) linearly with increased supplemental Met. Hepatic Met, vitamin B-12, S-adenosylmethionine and S-adenosylhomocysteine were not affected by Met supplementation. Hepatic folates tended (P = 0.07) to decrease linearly with Met supplementation. All three enzymes were detected in hepatic tissue of our steers. Hepatic CS activity was not affected by Met supplementation. Hepatic MS decreased (P < 0.01) linearly with increasing Met supply, and hepatic BHMT activity responded quadratically (P = 0.04), with 0 and 10 g/d Met being higher than the intermediate level. Data from this experiment indicate that sulfur amino acid metabolism may be regulated differently in cattle than in other tested species.
    • Accession Number:
      0 (Amino Acids)
      AE28F7PNPL (Methionine)
      EC 2.1.1.- (Methyltransferases)
      EC 2.1.1.13 (5-Methyltetrahydrofolate-Homocysteine S-Methyltransferase)
      EC 2.1.1.5 (Betaine-Homocysteine S-Methyltransferase)
      EC 4.2.1.22 (Cystathionine beta-Synthase)
      N762921K75 (Nitrogen)
    • Publication Date:
      Date Created: 20020705 Date Completed: 20020726 Latest Revision: 20180330
    • Publication Date:
      20231215
    • Accession Number:
      10.1093/jn/132.7.2004
    • Accession Number:
      12097683