@article {864,
	title = {In vitro polymerization and copolymerization of 3-hydroxypropionyl-CoA with the PHB synthase from Ralstonia eutropha.},
	journal = {Biomacromolecules},
	volume = {1},
	year = {2000},
	month = {2000 Fall},
	pages = {433-9},
	abstract = {The poly(3-hydroxybutyrate) (PHB) synthase of Ralstonia eutropha, which was produced by a recombinant strain of Escherichia coli and purified in one step with a methyl-HIC column to a purity of more than 90\%, was used to polymerize 3-hydroxypropionyl-CoA (3HPCoA) and to copolymerize 3HPCoA with 3-hydroxybutyryl-CoA (3HBCoA). A Km of 189 microM and a kcat of 10 s-1 were determined for the activity of the enzyme in the polymerization reaction of 3HPCoA based on the assumption that the dimer form of PHB synthase was the active form. Free coenzyme A was found to be a very effective competitive inhibitor for the polymerization of 3HPCoA with a Ki of 85 microM. The maximum degree of conversion of 3HPCoA to polymer was less than 40\%. In the simultaneous copolymerization reactions of these two monomers, both the turnover number for the copolymerization reaction and the maximum degree of conversion of 3HPCoA and 3HBCoA to copolymers increased with an increase in the amount of 3HBCoA in the monomer mixture. However, the maximum conversion of 3HPCoA to copolymer was always less than 35\%, regardless of the ratio of 3HPCoA to 3HBCoA. Block copolymers were obtained by the sequential copolymerization of the two monomers and these copolymers had a much narrower molecular weight distribution than those obtained by the simultaneous copolymerization for the same molar ratio of 3HPCoA to 3HBCoA.},
	keywords = {Acyltransferases, Coenzyme A, Escherichia coli, Kinetics, Magnetic Resonance Spectroscopy, Molecular Weight},
	issn = {1525-7797},
	author = {Song, J J and Zhang, S and Lenz, R W and Goodwin, S}
}
@article {871,
	title = {Influence of mass transfer limitations on determination of the half saturation constant for hydrogen uptake in a mixed-culture CH(4)-producing enrichment.},
	journal = {Biotechnol Bioeng},
	volume = {40},
	year = {1992},
	month = {1992 Oct 5},
	pages = {768-76},
	abstract = {There is strong evidence in the literature supporting the existence of significant mass transfer limitations on the kinetics of exogenous H(2) consumption by methanogens. The half saturation constant for H (2) uptake by a mixed-culture, CH(4) producing enrichment was measured using an experimental protocol that avoided internal mass transfer limitations. The value obtained was two orders of magnitude smaller than any other previously reported. A mathematical model for acetogenic syntrophic associations was developed to check the capacity of H(2) as electron transporter between syntrophic partners. It was found that H(2) diffusion could account for the rate of transport of electrons between the syntrophic microorganisms and that formate is not a necessary intermediate. The possibility that formate may be an intermediate in this system was not ruled out. A Monod-type kinetic equation was modified to include the observed H(2) threshold effect. This modified equation was used to predict the CH(4)-production rate in a batch-fed digester. The results show that the external and internal H(2) pools are kinetically coupled.},
	issn = {0006-3592},
	doi = {10.1002/bit.260400704},
	author = {Giraldo-Gomez, E and Goodwin, S and Switzenbaum, M S}
}
