Substrate specificity and stabilization by thiamine pyrophosphate of rat liver branched chain α-ketoacid dehydrogenase

Dean J. Danner, Sandra Lemmon, Louis J. Elsas

Research output: Contribution to journalArticle

25 Citations (Scopus)

Abstract

Rat liver branched chain α-ketoacid dehydrogenase has been solubilized and used to investigate the substrate specificity, cofactor requirements, and stabilizing properties of thiamine pyrophosphate for this enzyme. Only the branched chain α-ketoacids are oxidatively decarboxylated with apparent Km values of 30, 32, and 35 μm for α-ketoisovalerate, α-ketoisocaproate and α-keto-β-methylvalerate, respectively. Maximal CO2 release requires the presence of CoASH, NAD+, Mg2+ and thiamine pyrophosphate. The ketoacids competitively inhibit one another, activity for all three show identical pH optimum and heat lability which supports the concept of single enzyme complex acting on all three substrates. The activity can be stabilized by thiamine pyrophosphate which provides a rationale for treatment of maple syrup urine disease with pharmacologic doses of thiamine.

Original languageEnglish
Pages (from-to)27-38
Number of pages12
JournalBiochemical Medicine
Volume19
Issue number1
DOIs
StatePublished - Jan 1 1978
Externally publishedYes

Fingerprint

3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)
Thiamine Pyrophosphate
Substrate Specificity
Liver
Rats
Stabilization
Substrates
Maple Syrup Urine Disease
Thiamine
Enzymes
Coenzyme A
NAD
Hot Temperature

ASJC Scopus subject areas

  • Biochemistry

Cite this

Substrate specificity and stabilization by thiamine pyrophosphate of rat liver branched chain α-ketoacid dehydrogenase. / Danner, Dean J.; Lemmon, Sandra; Elsas, Louis J.

In: Biochemical Medicine, Vol. 19, No. 1, 01.01.1978, p. 27-38.

Research output: Contribution to journalArticle

@article{fa006a91eaf8482b8b4245d63fd32588,
title = "Substrate specificity and stabilization by thiamine pyrophosphate of rat liver branched chain α-ketoacid dehydrogenase",
abstract = "Rat liver branched chain α-ketoacid dehydrogenase has been solubilized and used to investigate the substrate specificity, cofactor requirements, and stabilizing properties of thiamine pyrophosphate for this enzyme. Only the branched chain α-ketoacids are oxidatively decarboxylated with apparent Km values of 30, 32, and 35 μm for α-ketoisovalerate, α-ketoisocaproate and α-keto-β-methylvalerate, respectively. Maximal CO2 release requires the presence of CoASH, NAD+, Mg2+ and thiamine pyrophosphate. The ketoacids competitively inhibit one another, activity for all three show identical pH optimum and heat lability which supports the concept of single enzyme complex acting on all three substrates. The activity can be stabilized by thiamine pyrophosphate which provides a rationale for treatment of maple syrup urine disease with pharmacologic doses of thiamine.",
author = "Danner, {Dean J.} and Sandra Lemmon and Elsas, {Louis J.}",
year = "1978",
month = "1",
day = "1",
doi = "10.1016/0006-2944(78)90004-2",
language = "English",
volume = "19",
pages = "27--38",
journal = "Molecular Genetics and Metabolism",
issn = "1096-7192",
publisher = "Academic Press Inc.",
number = "1",

}

TY - JOUR

T1 - Substrate specificity and stabilization by thiamine pyrophosphate of rat liver branched chain α-ketoacid dehydrogenase

AU - Danner, Dean J.

AU - Lemmon, Sandra

AU - Elsas, Louis J.

PY - 1978/1/1

Y1 - 1978/1/1

N2 - Rat liver branched chain α-ketoacid dehydrogenase has been solubilized and used to investigate the substrate specificity, cofactor requirements, and stabilizing properties of thiamine pyrophosphate for this enzyme. Only the branched chain α-ketoacids are oxidatively decarboxylated with apparent Km values of 30, 32, and 35 μm for α-ketoisovalerate, α-ketoisocaproate and α-keto-β-methylvalerate, respectively. Maximal CO2 release requires the presence of CoASH, NAD+, Mg2+ and thiamine pyrophosphate. The ketoacids competitively inhibit one another, activity for all three show identical pH optimum and heat lability which supports the concept of single enzyme complex acting on all three substrates. The activity can be stabilized by thiamine pyrophosphate which provides a rationale for treatment of maple syrup urine disease with pharmacologic doses of thiamine.

AB - Rat liver branched chain α-ketoacid dehydrogenase has been solubilized and used to investigate the substrate specificity, cofactor requirements, and stabilizing properties of thiamine pyrophosphate for this enzyme. Only the branched chain α-ketoacids are oxidatively decarboxylated with apparent Km values of 30, 32, and 35 μm for α-ketoisovalerate, α-ketoisocaproate and α-keto-β-methylvalerate, respectively. Maximal CO2 release requires the presence of CoASH, NAD+, Mg2+ and thiamine pyrophosphate. The ketoacids competitively inhibit one another, activity for all three show identical pH optimum and heat lability which supports the concept of single enzyme complex acting on all three substrates. The activity can be stabilized by thiamine pyrophosphate which provides a rationale for treatment of maple syrup urine disease with pharmacologic doses of thiamine.

UR - http://www.scopus.com/inward/record.url?scp=0017878129&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0017878129&partnerID=8YFLogxK

U2 - 10.1016/0006-2944(78)90004-2

DO - 10.1016/0006-2944(78)90004-2

M3 - Article

C2 - 203270

AN - SCOPUS:0017878129

VL - 19

SP - 27

EP - 38

JO - Molecular Genetics and Metabolism

JF - Molecular Genetics and Metabolism

SN - 1096-7192

IS - 1

ER -