Biomaterial Database

An extracellular polyhydroxybutyrate depolymerase in Thermus thermophilus HB8. 2009

Christos P Papaneophytou, and Anastasia A Pantazaki, and Dimitrios A Kyriakidis

Department of Chemistry, Aristotle University of Thessaloniki, Greece.

The thermophilic bacterium Thermus thermophilus HB8 has been characterized as a polyhydroxybutyrate (PHB)-degrading microorganism since it grows efficiently and forms clear zones on agar plates containing PHB as sole carbon source. T. thermophilus extracellular PHB depolymerase was purified to homogeneity using an affinity chromatography protocol. The purified enzyme was estimated to have an apparent molecular mass of 42 kDa. The extracellular PHB depolymerase gene was identified as the TTHA0199 gene product of T. thermophilus HB8. The amino acid sequence of the TTHA0199 gene product shared significant homologies to other carboxylesterases. A catalytic triad was identified consisting of S(183), E(310), and H(405). A pentapeptide sequence (GX(1)SX(2)G) exists within the molecule, characteristic for PHB depolymerases (lipase box) and for other serine hydrolases. Purified extracellular PHB depolymerase was stable at high temperatures with an optimum activity at pH 8.0. The apparent Km value of the purified enzyme for PHB was 53 microg/ml. As the main product of the enzymic hydrolysis of PHB, the monomer 3-hydroxybutyrate was identified, suggesting that the enzyme acts principally as an exo-type hydrolase.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D008969	Molecular Sequence Data	Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.	Sequence Data, Molecular,Molecular Sequencing Data,Data, Molecular Sequence,Data, Molecular Sequencing,Sequencing Data, Molecular
D008970	Molecular Weight	The sum of the weight of all the atoms in a molecule.	Molecular Weights,Weight, Molecular,Weights, Molecular
D011091	Polyesters	Polymers of organic acids and alcohols, with ester linkages--usually polyethylene terephthalate; can be cured into hard plastic, films or tapes, or fibers which can be woven into fabrics, meshes or velours.	Polyester
D002265	Carboxylic Ester Hydrolases	Enzymes which catalyze the hydrolysis of carboxylic acid esters with the formation of an alcohol and a carboxylic acid anion.	Carboxylesterases,Ester Hydrolases, Carboxylic,Hydrolases, Carboxylic Ester
D002846	Chromatography, Affinity	A chromatographic technique that utilizes the ability of biological molecules, often ANTIBODIES, to bind to certain ligands specifically and reversibly. It is used in protein biochemistry. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)	Chromatography, Bioaffinity,Immunochromatography,Affinity Chromatography,Bioaffinity Chromatography
D004795	Enzyme Stability	The extent to which an enzyme retains its structural conformation or its activity when subjected to storage, isolation, and purification or various other physical or chemical manipulations, including proteolytic enzymes and heat.	Enzyme Stabilities,Stabilities, Enzyme,Stability, Enzyme
D006863	Hydrogen-Ion Concentration	The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH	pH,Concentration, Hydrogen-Ion,Concentrations, Hydrogen-Ion,Hydrogen Ion Concentration,Hydrogen-Ion Concentrations
D006885	Hydroxybutyrates	Salts and esters of hydroxybutyric acid.	Hydroxybutyric Acid Derivatives,Hydroxybutyric Acids,Acid Derivatives, Hydroxybutyric
D000595	Amino Acid Sequence	The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.	Protein Structure, Primary,Amino Acid Sequences,Sequence, Amino Acid,Sequences, Amino Acid,Primary Protein Structure,Primary Protein Structures,Protein Structures, Primary,Structure, Primary Protein,Structures, Primary Protein