RGD Reference Report - Substrate specificities of 3-oxoacyl-CoA thiolase A and sterol carrier protein 2/3-oxoacyl-CoA thiolase purified from normal rat liver peroxisomes. Sterol carrier protein 2/3-oxoacyl-CoA thiolase is involved in the metabolism of 2-methyl-branched fatty acids and bile acid intermediates. - Rat Genome Database

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Substrate specificities of 3-oxoacyl-CoA thiolase A and sterol carrier protein 2/3-oxoacyl-CoA thiolase purified from normal rat liver peroxisomes. Sterol carrier protein 2/3-oxoacyl-CoA thiolase is involved in the metabolism of 2-methyl-branched fatty acids and bile acid intermediates.

Authors: Antonenkov, V D  Van Veldhoven, P P  Waelkens, E  Mannaerts, G P 
Citation: Antonenkov VD, etal., J Biol Chem. 1997 Oct 10;272(41):26023-31. doi: 10.1074/jbc.272.41.26023.
RGD ID: 21201257
Pubmed: PMID:9325339   (View Abstract at PubMed)
DOI: DOI:10.1074/jbc.272.41.26023   (Journal Full-text)

The two main thiolase activities present in isolated peroxisomes from normal rat liver were purified to near homogeneity. On sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the first enzyme preparation displayed a single band of 41 kDa that was identified as 3-oxoacyl-CoA thiolase A (thiolase A) by N-terminal amino acid sequencing. The second enzyme preparation consisted of a 58- and a 46-kDa band. The 58-kDa polypeptide reacted with antibodies raised against either sterol carrier protein 2 or the thiolase domain of sterol carrier protein 2/3-oxoacyl-CoA thiolase (SCP-2/thiolase), formerly also called sterol carrier protein X, whereas the 46-kDa polypeptide reacted only with the antibodies raised against the thiolase domain. Internal peptide sequencing confirmed that the 58-kDa polypeptide is SCP-2/thiolase and that the 46-kDa polypeptide is the thiolase domain of SCP-2/thiolase. Thiolase A catalyzed the cleavage of short, medium, and long straight chain 3-oxoacyl-CoAs, medium chain 3-oxoacyl-CoAs being the best substrates. The enzyme was inactive with the 2-methyl-branched 3-oxo-2-methylpalmitoyl-CoA and with the bile acid intermediate 24-oxo-trihydroxycoprostanoyl-CoA. SCP-2/thiolase was active with medium and long straight chain 3-oxoacyl-CoAs but also with the 2-methyl-branched 3-oxoacyl-CoA and the bile acid intermediate. In peroxisomal extracts, more than 90% of the thiolase activity toward straight chain 3-oxoacyl-CoAs was associated with thiolase A. Kinetic parameters (Km and Vmax) were determined for each enzyme with the different substrates. Our results indicate the following: 1) the two (main) thiolases present in peroxisomes from normal rat liver are thiolase A and SCP-2/thiolase; 2) thiolase A is responsible for the thiolytic cleavage of straight chain 3-oxoacyl-CoAs; and 3) SCP-2/thiolase is responsible for the thiolytic cleavage of the 3-oxoacyl-CoA derivatives of 2-methyl-branched fatty acids and the side chain of cholesterol.



Gene Ontology Annotations    Click to see Annotation Detail View

Biological Process

  
Object SymbolSpeciesTermQualifierEvidenceWithNotesSourceOriginal Reference(s)
Acaa1aRatbile acid metabolic process involved_inIDA PMID:9325339UniProt 
Scp2Ratbile acid metabolic process involved_inIDA PMID:9325339UniProt 
Acaa1aRatfatty acid beta-oxidation involved_inIDA PMID:9325339UniProt 
Scp2Ratfatty acid beta-oxidation involved_inIDA PMID:9325339UniProt 

Cellular Component

  
Object SymbolSpeciesTermQualifierEvidenceWithNotesSourceOriginal Reference(s)
Acaa1aRatperoxisome located_inIDA PMID:9325339UniProt 
Scp2Ratperoxisome located_inIDA PMID:9325339UniProt 

Molecular Function

  
Object SymbolSpeciesTermQualifierEvidenceWithNotesSourceOriginal Reference(s)
Acaa1aRatacetyl-CoA C-acyltransferase activity enablesIDA PMID:9325339UniProt 
Scp2Ratacetyl-CoA C-acyltransferase activity enablesIDA PMID:9325339UniProt 
Acaa1aRatacetyl-CoA C-myristoyltransferase activity enablesIDA PMID:9325339UniProt 
Scp2Ratacetyl-CoA C-myristoyltransferase activity enablesIDA PMID:9325339UniProt 

Objects Annotated

Genes (Rattus norvegicus)
Acaa1a  (acetyl-CoA acyltransferase 1A)
Scp2  (sterol carrier protein 2)


Additional Information