scholarly journals Purification and subunit structure of propionyl coenzyme A carboxylase of Mycobacterium smegmatis.

1979 ◽  
Vol 254 (13) ◽  
pp. 5888-5891
Author(s):  
K P Henrikson ◽  
S H Allen
Keyword(s):  
Mycobacterium Smegmatis ◽  
Coenzyme A ◽  
Subunit Structure

Succinyl Coenzyme A Synthetase of Pig Heart: Studies of the Subunit Structure and of Phosphoenzyme Formation

1972 ◽  
Vol 50 (7) ◽  
pp. 719-724 ◽  
Author(s):  
E. R. Brownie ◽  
W. A. Bridger
Keyword(s):  
Coenzyme A ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Standard Free Energy ◽  
Subunit Structure ◽  
Standard Free Energy Change ◽  
Molecular Weights ◽  
Similarities And Differences ◽  
Bacterial Sources ◽  
Succinyl Coenzyme A Synthetase

Succinyl coenzyme A synthetase from pig heart (molecular weight approximately 75 000) gives rise to two species of subunits when subjected to polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. The molecular weights of the constituent subunits are estimated to be about 42 500 and 34 500, suggesting that the enzyme is a dimer. The presence of saturating concentrations of guanosine 5′-triphosphate (GTP) results in the formation of one phosphohistidine residue per molecule of enzyme; the site of phosphorylation is in the smaller subunit. The standard free energy change for phosphorylation of the enzyme by GTP is approximately −400 cal/mol. The results point to both interesting similarities and differences in succinyl-CoA synthetases isolated from mammalian and bacterial sources.

scholarly journals Characterization of a Bifunctional Archaeal Acyl Coenzyme A Carboxylase

2003 ◽  
Vol 185 (3) ◽  
pp. 938-947 ◽  
Author(s):  
Songkran Chuakrut ◽  
Hiroyuki Arai ◽  
Masaharu Ishii ◽  
Yasuo Igarashi
Keyword(s):  
Amino Acid ◽  
Binding Site ◽  
Coenzyme A ◽  
Amino Acid Sequences ◽  
Carrier Protein ◽  
Subunit Structure ◽  
Biotin Carboxylase ◽  
Acetyl Coa ◽  
Biotin Carboxyl Carrier Protein ◽  
Acyl Coenzyme A

ABSTRACT Acyl coenzyme A carboxylase (acyl-CoA carboxylase) was purified from Acidianus brierleyi. The purified enzyme showed a unique subunit structure (three subunits with apparent molecular masses of 62, 59, and 20 kDa) and a molecular mass of approximately 540 kDa, indicating an α4β4γ4 subunit structure. The optimum temperature for the enzyme was 60 to 70°C, and the optimum pH was around 6.4 to 6.9. Interestingly, the purified enzyme also had propionyl-CoA carboxylase activity. The apparent Km for acetyl-CoA was 0.17 ± 0.03 mM, with a V max of 43.3 ± 2.8 U mg−1, and the Km for propionyl-CoA was 0.10 ± 0.008 mM, with a V max of 40.8 ± 1.0 U mg−1. This result showed that A. brierleyi acyl-CoA carboxylase is a bifunctional enzyme in the modified 3-hydroxypropionate cycle. Both enzymatic activities were inhibited by malonyl-CoA, methymalonyl-CoA, succinyl-CoA, or CoA but not by palmitoyl-CoA. The gene encoding acyl-CoA carboxylase was cloned and characterized. Homology searches of the deduced amino acid sequences of the 62-, 59-, and 20-kDa subunits indicated the presence of functional domains for carboxyltransferase, biotin carboxylase, and biotin carboxyl carrier protein, respectively. Amino acid sequence alignment of acetyl-CoA carboxylases revealed that archaeal acyl-CoA carboxylases are closer to those of Bacteria than to those of Eucarya. The substrate-binding motifs of the enzymes are highly conserved among the three domains. The ATP-binding residues were found in the biotin carboxylase subunit, whereas the conserved biotin-binding site was located on the biotin carboxyl carrier protein. The acyl-CoA-binding site and the carboxybiotin-binding site were found in the carboxyltransferase subunit.

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