@article {863,
	title = {Enzymatic hydrolysis of oligomeric models of poly-3-hydroxybutyrate.},
	journal = {Biomacromolecules},
	volume = {1},
	year = {2000},
	month = {2000 Winter},
	pages = {577-83},
	abstract = {The mechanism of the enzymatic degradation of poly([R]-3-hydroxybutyrate) (PHB) was investigated by using well-defined model substrates, including both linear and cyclic [R]-3-hydroxybutyrate (3HB) and [R]-3-hydroxyvalerate (3HV) oligomers, with two different PHB depolymerases. The linear and cyclic oligomers containing from 2 to 10 repeating units were hydrolyzed in solutions of the depolymerase isolated from Aspergillus fumigatus and Alcaligenes faecalis, and the rates of hydrolysis and types of products formed were characterized. Both of the depolymerases catalyzed the hydrolysis of the cyclic oligomers (macrolides) which contained more than three 3HB and 3HV repeating units. The degradation reactions of the linear and cyclic 3HB oligomers with the A. fumigatus depolymerase gave similar ratios of monomer-to-dimer products, but PHB itself formed mostly monomer on hydrolysis, indicating that the enzymatic hydrolysis reactions occurred by different mechanisms for these different types of substrates. The results of this study conclusively show that at least the endo mode of polymer hydrolysis occurs with the two enzymes studied, while the A. fumigatus depolymerase was found to utilize both endo and exo modes of hydrolysis to efficiently degrade PHB and 3HB oligomers.},
	keywords = {3-Hydroxybutyric Acid, Alcaligenes, Aspergillus fumigatus, Carboxylic Ester Hydrolases, Escherichia coli, Hydrolysis, Kinetics, Macrolides, Models, Chemical, Polymers},
	issn = {1525-7797},
	author = {Scherer, T M and Fuller, R C and Goodwin, S and Lenz, R W}
}
@article {869,
	title = {Extracellular degradation of medium chain length poly(beta-hydroxyalkanoates) by Comamonas sp.},
	journal = {Int J Biol Macromol},
	volume = {25},
	year = {1999},
	month = {1999 Jun-Jul},
	pages = {135-43},
	abstract = {The PHA-degrading isolate, strain P37C, was enriched from residential compost for its ability to hydrolyze the medium chain length PHA, poly(beta-hydroxyoctanoate) (PHO). It was subsequently found to grow on a wide range of PHAs, including both short chain length and medium chain length PHAs. The isolate was identified as belonging to the genus Comamonas. Strain P37C formed clear zones on poly(beta-hydroxybutyrate) (PHB), (PHO) and poly(beta-hydroxyphenylvalerate) (PHPV) overlay plates. PHA clear zone tubes were prepared using seven different kinds of PHAs, ranging from PHB with four-carbon repeating units, to poly(beta-hydroxyoctanoate-co-beta-hydroxyundecanoate) (PHOU) with 8- and 11-carbon repeating units. There was a direct correlation between PHA side chain length and rate of hydrolysis of the PHAs. A series of PHOUs containing varying percentages of unsaturated bonds were used to make a series of epoxidized PHOUs (PHOEs) with varying percentages of epoxy functions. Results of clear zone tube assays showed that these functionalized PHAs were all biodegradable by strain P37C, and there was no apparent correlation between rate of biodegradation and the proportion of functional groups in the PHAs. Biodegradability of these PHAs was verified using respirometry and enzyme assays. Cell-free supernatants containing activity toward PHAs were prepared, and strain P37C was shown to synthesize at least two distinct PHA depolymerases for the hydrolysis of SCL and MCL PHAs.},
	keywords = {Carboxylic Ester Hydrolases, Gram-Negative Aerobic Rods and Cocci, Kinetics, Polyesters, Structure-Activity Relationship, Substrate Specificity},
	issn = {0141-8130},
	author = {Quinteros, R and Goodwin, S and Lenz, R W and Park, W H}
}
@article {870,
	title = {Extracellular polymerization of 3-hydroxyalkanoate monomers with the polymerase of Alcaligenes eutrophus.},
	journal = {Int J Biol Macromol},
	volume = {25},
	year = {1999},
	month = {1999 Jun-Jul},
	pages = {55-60},
	abstract = {Previous investigations on the role of the polymerase in the synthesis of poly-3-hydroxybutyrate (PHB) are reviewed, and the results from earlier in vitro studies on the activity and selectivity of the polymerase of Alcaligenes eutrophus are discussed. In the present study the effect of glycerol on stabilizing the polymerase after purification and on eliminating the lag phase in in vitro polymerization reactions of 3-hydroxybutyl CoA (HBCoA), and 3-hydroxyvaleryl CoA (HVCoA) are described. K(M) values were determined for the activity of the polymerase with both HBCoA and HVCoA, and the rates of propagation for both monomers were estimated. With a racemic mixture of HBCoA, the enzyme polymerized only the [R] monomer.},
	keywords = {Acyl Coenzyme A, Acyltransferases, Alcaligenes, Hydroxybutyrates, Kinetics, Polyesters, Substrate Specificity},
	issn = {0141-8130},
	author = {Lenz, R W and Farcet, C and Dijkstra, P J and Goodwin, S and Zhang, S}
}
