<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Scherer, T M</style></author><author><style face="normal" font="default" size="100%">Fuller, R C</style></author><author><style face="normal" font="default" size="100%">Goodwin, S</style></author><author><style face="normal" font="default" size="100%">Lenz, R W</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Enzymatic hydrolysis of oligomeric models of poly-3-hydroxybutyrate.</style></title><secondary-title><style face="normal" font="default" size="100%">Biomacromolecules</style></secondary-title><alt-title><style face="normal" font="default" size="100%">Biomacromolecules</style></alt-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">3-Hydroxybutyric Acid</style></keyword><keyword><style  face="normal" font="default" size="100%">Alcaligenes</style></keyword><keyword><style  face="normal" font="default" size="100%">Aspergillus fumigatus</style></keyword><keyword><style  face="normal" font="default" size="100%">Carboxylic Ester Hydrolases</style></keyword><keyword><style  face="normal" font="default" size="100%">Escherichia coli</style></keyword><keyword><style  face="normal" font="default" size="100%">Hydrolysis</style></keyword><keyword><style  face="normal" font="default" size="100%">Kinetics</style></keyword><keyword><style  face="normal" font="default" size="100%">Macrolides</style></keyword><keyword><style  face="normal" font="default" size="100%">Models, Chemical</style></keyword><keyword><style  face="normal" font="default" size="100%">Polymers</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2000</style></year><pub-dates><date><style  face="normal" font="default" size="100%">2000 Winter</style></date></pub-dates></dates><volume><style face="normal" font="default" size="100%">1</style></volume><pages><style face="normal" font="default" size="100%">577-83</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">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.</style></abstract><issue><style face="normal" font="default" size="100%">4</style></issue><custom1><style face="normal" font="default" size="100%">http://www.ncbi.nlm.nih.gov/pubmed/11710184?dopt=Abstract</style></custom1></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Lenz, R W</style></author><author><style face="normal" font="default" size="100%">Farcet, C</style></author><author><style face="normal" font="default" size="100%">Dijkstra, P J</style></author><author><style face="normal" font="default" size="100%">Goodwin, S</style></author><author><style face="normal" font="default" size="100%">Zhang, S</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Extracellular polymerization of 3-hydroxyalkanoate monomers with the polymerase of Alcaligenes eutrophus.</style></title><secondary-title><style face="normal" font="default" size="100%">Int J Biol Macromol</style></secondary-title><alt-title><style face="normal" font="default" size="100%">Int. J. Biol. Macromol.</style></alt-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Acyl Coenzyme A</style></keyword><keyword><style  face="normal" font="default" size="100%">Acyltransferases</style></keyword><keyword><style  face="normal" font="default" size="100%">Alcaligenes</style></keyword><keyword><style  face="normal" font="default" size="100%">Hydroxybutyrates</style></keyword><keyword><style  face="normal" font="default" size="100%">Kinetics</style></keyword><keyword><style  face="normal" font="default" size="100%">Polyesters</style></keyword><keyword><style  face="normal" font="default" size="100%">Substrate Specificity</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">1999</style></year><pub-dates><date><style  face="normal" font="default" size="100%">1999 Jun-Jul</style></date></pub-dates></dates><volume><style face="normal" font="default" size="100%">25</style></volume><pages><style face="normal" font="default" size="100%">55-60</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">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.</style></abstract><issue><style face="normal" font="default" size="100%">1-3</style></issue><custom1><style face="normal" font="default" size="100%">http://www.ncbi.nlm.nih.gov/pubmed/10416650?dopt=Abstract</style></custom1></record></records></xml>