Distribution of branched-chain alpha-keto acid dehydrogenases in primate tissues.

Khatra, Balwant S.; Chawla, Rajender K.; Sewell, Charles W.; Rudman, Daniel

doi:10.1172/jci108671

Cited by 94 publications

(24 citation statements)

References 17 publications

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“…In the leucine metabolism of fibroblasts as well as other nonhepatic tissues, the dehydrogenase reaction of the branchedchain ketoacid is thought to be limiting (20,(25)(26)(27). This is consistent with the fact that the concentrations of a-ketoisocaproic acid in fibroblasts of patients with MSUD are not much lower than those of control fibroblasts (20).…”

Section: Discussionsupporting

confidence: 58%

Metabolism of Branched-Chain Amino Acids in Fibroblasts from Patients with Maple Syrup Urine Disease and Other Abnormalities of Branched-Chain Ketoacid Dehydrogenase Activity

1986

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ABSTRACT. The metabolism of branched-chain amino acids was studied in cultured fibroblasts from patients with branched-chain ketoacid dehydrogenase deficiency using 1-I4C-and UL-14C-leucine and valine. The formation of I4CO2 from 1-14C-valine or l-14C-leucine was 1-3% of normal. In fibroblasts of patients with associated lactic acidemia the values were 4-29% of control. Analysis of organic acid products revealed that in both patients and controls the amount of labeled a-ketoisovalerate recovered after incubation with l-14C-valine was one-third of the amount of a-ketoisocaproate recovered after incubation with I-"C-leucine. Very little a-hydroxyisocaproate was produced, while the amount of a-hydroxyisovalerate was about 10% of the a-ketoisovalerate. Unexpectedly P-hydroxyisobutyrate ws found to be the major metabolic product of UL-14C-valine in normal fibroblasts. Large accumulations of P-hydroxyisovalerate were found in normal fibroblasts using UL-14C-leucine. There were little or no conversions to these compounds in fibroblasts of patients with branched-chain ketoacid dehydrogenase deficiency. There were substantial conversions in the patients in whom dehydrogenase deficiency was associated with lactic acidemia. (Pediatr Res 20: 169-174, 1986) Abbreviations BCKADI-I, branched-chain ketoacid dehydrogenase MSUD, maple syrup urine disease E3, dihydrolipoyl dehydrogenase LPC, liquid partition chromatography MSUD results from defective activity of the BCKADH complex (1). The concentrations of leucine in the blood of patients with MSUD are generally higher than those of valine and isoleucine, indicating that there are differences in metabolism among the three ketoacids. Several variant forms of BCKADH deficiency have been described (2-4). Patients have also been described in whom deficiency of BCKADH was secondary to a deficiency of E3 (5, 6). We have also studied a patient in whom

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Section: Discussionsupporting

confidence: 58%

Metabolism of Branched-Chain Amino Acids in Fibroblasts from Patients with Maple Syrup Urine Disease and Other Abnormalities of Branched-Chain Ketoacid Dehydrogenase Activity

1986

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“…Whether man is able to undergo similar adaptations to chronic clofibrate therapy is not known. Moreover, recent studies by Khatra et al (28) indicate that skeletal muscle in man may be more dependent on the branched chain amino acids as carbon sources than that in the rat. The majority (76%) of total body branched chain keto-acid dehydrogenase activity in the rat is in liver, whereas in man the majority (62%) of total body dehydrogenase activity is in skeletal muscle.…”

Section: Discussionmentioning

confidence: 99%

Branched Chain Amino Acid Oxidation in Cultured Rat Skeletal Muscle Cells

Pardridge¹,

Casanello-Ertl²,

Duducgian-Vartavarian³

1980

J. Clin. Invest.

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“…Further, the observed increases during endurance exercise are greater in humans than in rodents (52), perhaps due to greater muscle dehydrogenase activity (61).…”

Section: Possibilitymentioning

confidence: 99%

Protein and Amino Acid Needs of the Strength Athlete

Lemon

1991

International Journal of Sport Nutrition

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The debate regarding optimal proteinlamino acid needs of strength athletes is an old one. Recent evidence indicates that actual requirements are higher than those of more sedentary individuals, although this is not widely recognized. Some data even suggest that high proteinlamino acid diets can enhance the development of muscle mass and strength when combined with heavy resistance exercise training. Novices may have higher needs than experienced strength athletes, and substantial interindividual variability exists. Perhaps the most important single factor determining absolute proteinlamino acid need is the adequacy of energy intake. Present data indicate that strength athletes should consume approximately 12-15% of their daily total energy intake as protein, or about 1.5-2.0 g proteinlkg*d-' (approximately 188-250% of the U.S. recommended dietary allowance). Although routinely consumed by many strength athletes, higher protein intakes have not been shown to be consistently effective and may even be associated with some health risks.Although for most of the 20th century nutritionists have generally believed that proteinlamino acid need is not substantially affected by strength training (87), many athletes, especially body builders, have routinely consumed very high protein diets (41,60). Apparently these individuals think such diets enhance performance, but their opinion is based primarily on hearsay or uncontrolled self-experimentation and therefore lacks the necessary objectivity to convince scientists. However, recent results from several laboratories suggest that the issue of whether such high proteinlamino acid diets are beneficial to strength athletes rnay need to be readdressed (66). This paper reviews new information relative to the previous literature and discusses the potential benefits of protein1 amino acid supplementation for the strength athlete. Importance of ProteinClearly, protein is an essential nutrient for all living organisms. With the exception of water, it is the largest component in our bodies and represents about 15 % of body weight. There are many proteins but each is made up of about 20 amino Peter W.R. Lemon is with the Applied

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Distribution of branched-chain alpha-keto acid dehydrogenases in primate tissues.

Cited by 94 publications

References 17 publications

Metabolism of Branched-Chain Amino Acids in Fibroblasts from Patients with Maple Syrup Urine Disease and Other Abnormalities of Branched-Chain Ketoacid Dehydrogenase Activity

Metabolism of Branched-Chain Amino Acids in Fibroblasts from Patients with Maple Syrup Urine Disease and Other Abnormalities of Branched-Chain Ketoacid Dehydrogenase Activity

Branched Chain Amino Acid Oxidation in Cultured Rat Skeletal Muscle Cells

Protein and Amino Acid Needs of the Strength Athlete

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