Document Detail


Transamination of neutral amino acids and 2-keto acids in pancreatic B-cell mitochondria.
MedLine Citation:
PMID:  2864344     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
High aminotransferase activities catalyzing the reactions between L-glutamate and L-glutamine and the aliphatic ketomonocarboxylic acids 2-ketoisocaproate, 2-ketocaproate, and 2-ketoisovalerate were observed in pancreatic B-cell mitochondria. While maximal rates of transamination with L-glutamate were observed in the presence of micromolar concentrations of keto acid, maximal rates of transamination with L-glutamine were recorded only in the presence of millimolar concentrations of keto acid. The insulin secretagogue 2-ketoisocaproate was the most effective transamination partner for L-glutamate, while the insulin secretagogue 2-ketocaproate was the most effective transamination partner for L-glutamine. Since B-cell mitochondria are well supplied with L-glutamate and L-glutamine, 2-ketoglutarate generation in the presence of these two neutral 2-keto acids may be an important prerequisite for their insulin secretory potency. High rates of transamination of 2-ketoglutarate were observed in the pancreatic B-cell mitochondria with the branched-chain amino acids L-leucine and L-valine, but not with L-norleucine. In connection with the ability of L-leucine to activate glutamate dehydrogenase, this high activity of the branched-chain amino acid aminotransferase in pancreatic B-cell mitochondria may provide an explanation for the insulin secretory potency of this amino acid.
Authors:
S Lenzen; W Schmidt; U Panten
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The Journal of biological chemistry     Volume:  260     ISSN:  0021-9258     ISO Abbreviation:  J. Biol. Chem.     Publication Date:  1985 Oct 
Date Detail:
Created Date:  1985-11-14     Completed Date:  1985-11-14     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  2985121R     Medline TA:  J Biol Chem     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  12629-34     Citation Subset:  IM    
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MeSH Terms
Descriptor/Qualifier:
Animals
Cytoplasm / enzymology
Glutamates / metabolism*
Glutamic Acid
Glutamine / metabolism*
Hexanoic Acids / metabolism
Islets of Langerhans / enzymology*
Keto Acids / metabolism*
Kinetics
Leucine / metabolism
Mice
Mice, Obese
Mitochondria / enzymology
Transaminases / metabolism*
Valine / metabolism
Chemical
Reg. No./Substance:
0/Glutamates; 0/Hexanoic Acids; 0/Keto Acids; 2492-75-3/alpha-ketocaproic acid; 56-85-9/Glutamine; 56-86-0/Glutamic Acid; 61-90-5/Leucine; 7004-03-7/Valine; 759-05-7/alpha-ketoisovalerate; 816-66-0/alpha-ketoisocaproic acid; EC 2.6.1.-/Transaminases

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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