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PMID:2317039
| Citation |
Thompson, DK and Chen, JS (1990) Purification and properties of an acetoacetyl coenzyme A-reacting phosphotransbutyrylase from Clostridium beijerinckii ("Clostridium butylicum") NRRL B593. Appl. Environ. Microbiol. 56:607-13 |
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| Abstract |
During the study of acetoacetyl coenzyme A (CoA)-reacting enzymes of Clostridium beijerinckii NRRL B593, a phosphate-dependent acetoacetyl-CoA-utilizing activity was detected in protein fractions devoid of thiolase and phosphotransacetylase. Further purification of this acetoacetyl-CoA-utilizing activity yielded an enzyme which may be designated as phosphotransbutyrylase (PTB; phosphate butyryltransferase [EC 2.3.1.19]). PTB from C. beijerinckii NRRL B593 was purified 160-fold with a yield of 14% and, with the best fractions, purified 190-fold to near homogeneity. It showed a native Mr of 205,000 and a subunit Mr of 33,000. PTB activity was sensitive to pH changes within the physiological range of 6 to 8. PTB exhibited a broad substrate specificity. The Km values at pH 7.5 for butyryl-CoA, acetoacetyl-CoA, and acetyl-CoA were 0.04, 1.10, and 3.33 mM, respectively. The Vmax values with butyryl-CoA and acetoacetyl-CoA were comparable, but the Vmax/Km was higher for butyryl-CoA than for acetoacetyl-CoA. An apparent Km of 6.5 mM for phosphate was obtained with butyryl-CoA as the cosubstrate, whereas it was 12.9 mM with acetoacetyl-CoA as the cosubstrate. It remains to be established whether the putative compound acetoacetyl phosphate is produced in the PTB-catalyzed reaction with acetoacetyl-CoA. |
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| Keywords |
Acetyl Coenzyme A; Acyl Coenzyme A; Acyltransferases/isolation & purification; Acyltransferases/metabolism; Clostridium/enzymology; Hydrogen-Ion Concentration; Kinetics; Molecular Weight; Protein Conformation; Substrate Specificity |
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Significance
Annotations
| Gene product | Qualifier | GO Term | Evidence Code | with/from | Aspect | Extension | Notes | Status |
|---|---|---|---|---|---|---|---|---|
|
enables |
GO:0050182: phosphate butyryltransferase activity |
ECO:0000314: direct assay evidence used in manual assertion |
F |
Seeded From UniProt |
complete | |||
| GO:0050182: phosphate butyryltransferase activity |
ECO:0000314: |
F |
Phosphotransbutyrylase (PTB) has phosphate-dependent regulation of acyl transferase activity (Figure 2), and separation of PTB from thiolase and phosphotransacetylase (Figure 1) further regulates transferase activity. |
complete | ||||
See also
References
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