Tags

Type your tag names separated by a space and hit enter

Identification of D-threo-alpha-methylisocitrate as stereochemically specific substrate for bovine heart aconitase and inhibitor of TPN-linked isocitrate dehydrogenase.
J Biol Chem. 1977 Apr 25; 252(8):2702-9.JB

Abstract

DL-threo-alpha-Methylisocitrate (3-hydroxy-1,2,3-butanetricarboxylate) is a substrate for bovine heart aconitase and an inhibitor of TPN-linked isocitrate dehydrogenase from liver and heart. The isomer of alpha-methylisocitrate formed from alpha-methyl-cis-aconitate (cis-2-butane-1,2,3-tricarboxylate) by aconitase inhibits TPN-linked isocitrate dehydrogenase and has been identified as D-threo-alpha-methylisocitrate (2S,3R)-3-hydroxy-1,2,3-butanetricarboxylate) by optical rotation and circular dichroism studies. Mitochondrial bovine heart aconitase catalyzes a reversible reaction between D-threo-alpha-methylisocitrate (Km, 0.2 mM) and alpha-methyl-cis-aconitate (Km, 0.05 mM) at pH 7.4. However, formation of methylcitrate (2-hydroxy-1,2,3-butanetricarboxylate) from these substrates or utilization of synthetic methylcitrate for formation of these products could not be demonstrated with bovine heart aconitase. DL-threo-alpha-Methylisocitrate is also a substrate for aconitase from rat liver cytosol (Km, 0.1 mM); Vmax with citrate is approximately 1.4 times that with DL-threo-alpha-methylisocitrate. The ratio of activities for these substrates observed with the bovine heart enzyme is about 5. Formation of alpha-methyl-cis-aconitate from synthetic methylcitrate could not be detected spectrophotometrically with the liver aconitase; if it occurs with either the liver or the heart enzyme, the rate would be less than 0.1% that obtained with DL-threo-alpha-methylisocitrate. A new synthesis of methylcitric acid in good yields from diethyl alpha-methyl-beta-ketoglutarate (diethyl 2-methyl-3-oxoglutarate) and cyanide has been described. NMR spectroscopy indicates that this synthetic methylcitric acid contains the two racemic pairs of diastereoisomers.

Authors

No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

856801

Citation

Beach, R L., et al. "Identification of D-threo-alpha-methylisocitrate as Stereochemically Specific Substrate for Bovine Heart Aconitase and Inhibitor of TPN-linked Isocitrate Dehydrogenase." The Journal of Biological Chemistry, vol. 252, no. 8, 1977, pp. 2702-9.
Beach RL, Aogaichi T, Plaut GW. Identification of D-threo-alpha-methylisocitrate as stereochemically specific substrate for bovine heart aconitase and inhibitor of TPN-linked isocitrate dehydrogenase. J Biol Chem. 1977;252(8):2702-9.
Beach, R. L., Aogaichi, T., & Plaut, G. W. (1977). Identification of D-threo-alpha-methylisocitrate as stereochemically specific substrate for bovine heart aconitase and inhibitor of TPN-linked isocitrate dehydrogenase. The Journal of Biological Chemistry, 252(8), 2702-9.
Beach RL, Aogaichi T, Plaut GW. Identification of D-threo-alpha-methylisocitrate as Stereochemically Specific Substrate for Bovine Heart Aconitase and Inhibitor of TPN-linked Isocitrate Dehydrogenase. J Biol Chem. 1977 Apr 25;252(8):2702-9. PubMed PMID: 856801.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Identification of D-threo-alpha-methylisocitrate as stereochemically specific substrate for bovine heart aconitase and inhibitor of TPN-linked isocitrate dehydrogenase. AU - Beach,R L, AU - Aogaichi,T, AU - Plaut,G W, PY - 1977/4/25/pubmed PY - 1977/4/25/medline PY - 1977/4/25/entrez SP - 2702 EP - 9 JF - The Journal of biological chemistry JO - J Biol Chem VL - 252 IS - 8 N2 - DL-threo-alpha-Methylisocitrate (3-hydroxy-1,2,3-butanetricarboxylate) is a substrate for bovine heart aconitase and an inhibitor of TPN-linked isocitrate dehydrogenase from liver and heart. The isomer of alpha-methylisocitrate formed from alpha-methyl-cis-aconitate (cis-2-butane-1,2,3-tricarboxylate) by aconitase inhibits TPN-linked isocitrate dehydrogenase and has been identified as D-threo-alpha-methylisocitrate (2S,3R)-3-hydroxy-1,2,3-butanetricarboxylate) by optical rotation and circular dichroism studies. Mitochondrial bovine heart aconitase catalyzes a reversible reaction between D-threo-alpha-methylisocitrate (Km, 0.2 mM) and alpha-methyl-cis-aconitate (Km, 0.05 mM) at pH 7.4. However, formation of methylcitrate (2-hydroxy-1,2,3-butanetricarboxylate) from these substrates or utilization of synthetic methylcitrate for formation of these products could not be demonstrated with bovine heart aconitase. DL-threo-alpha-Methylisocitrate is also a substrate for aconitase from rat liver cytosol (Km, 0.1 mM); Vmax with citrate is approximately 1.4 times that with DL-threo-alpha-methylisocitrate. The ratio of activities for these substrates observed with the bovine heart enzyme is about 5. Formation of alpha-methyl-cis-aconitate from synthetic methylcitrate could not be detected spectrophotometrically with the liver aconitase; if it occurs with either the liver or the heart enzyme, the rate would be less than 0.1% that obtained with DL-threo-alpha-methylisocitrate. A new synthesis of methylcitric acid in good yields from diethyl alpha-methyl-beta-ketoglutarate (diethyl 2-methyl-3-oxoglutarate) and cyanide has been described. NMR spectroscopy indicates that this synthetic methylcitric acid contains the two racemic pairs of diastereoisomers. SN - 0021-9258 UR - https://www.unboundmedicine.com/medline/citation/856801/Identification_of_D_threo_alpha_methylisocitrate_as_stereochemically_specific_substrate_for_bovine_heart_aconitase_and_inhibitor_of_TPN_linked_isocitrate_dehydrogenase_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0021-9258(17)40516-3 DB - PRIME DP - Unbound Medicine ER -