Enzymatic reactions in non-conventional media: Prediction of solvent water content for optimum water activity

Voutsas, EC; Spiliotis, NM; Tassios, DP

dc.contributor.author	Voutsas, EC	en
dc.contributor.author	Spiliotis, NM	en
dc.contributor.author	Tassios, DP	en
dc.date.accessioned	2014-03-01T01:16:34Z
dc.date.available	2014-03-01T01:16:34Z
dc.date.issued	2001	en
dc.identifier.issn	1024-2422	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/14080
dc.subject	Enzymatic reactions	en
dc.subject	LCVM	en
dc.subject	UNIFAC	en
dc.subject	Water activity	en
dc.subject.classification	Biochemistry & Molecular Biology	en
dc.subject.classification	Biotechnology & Applied Microbiology	en
dc.subject.other	Esterification	en
dc.subject.other	Hydrophobicity	en
dc.subject.other	Organic solvents	en
dc.subject.other	Pressure effects	en
dc.subject.other	Temperature control	en
dc.subject.other	Water	en
dc.subject.other	Water activity	en
dc.subject.other	Enzyme kinetics	en
dc.subject.other	enzyme	en
dc.subject.other	organic solvent	en
dc.subject.other	water	en
dc.subject.other	article	en
dc.subject.other	chemical composition	en
dc.subject.other	concentration response	en
dc.subject.other	culture medium	en
dc.subject.other	enzyme activity	en
dc.subject.other	enzyme mechanism	en
dc.subject.other	equilibrium constant	en
dc.subject.other	esterification	en
dc.subject.other	hydrophobicity	en
dc.subject.other	organic chemistry	en
dc.subject.other	prediction	en
dc.subject.other	pressure	en
dc.subject.other	reaction analysis	en
dc.subject.other	solvation	en
dc.subject.other	temperature	en
dc.subject.other	water analysis	en
dc.subject.other	water content	en
dc.title	Enzymatic reactions in non-conventional media: Prediction of solvent water content for optimum water activity	en
heal.type	journalArticle	en
heal.identifier.primary	10.3109/10242420109003639	en
heal.identifier.secondary	http://dx.doi.org/10.3109/10242420109003639	en
heal.language	English	en
heal.publicationDate	2001	en
heal.abstract	Most enzymes provide their optimum performance at a given water activity (a,), which is generally solvent independent. For a given organic liquid solvent at a specific temperature or for a supercritical solvent at a specific temperature and pressure this corresponds to a water concentration in which water has the desired activity. We present here a methodology for predicting this water concentration thus reducing substantially the amount of experimental work needed to find the optimum solvent with respect to equilibrium conversion. If the enzyme optimum water activity is known, the methodology predicts the required water content in the solvent to achieve this a(w) value. If, in addition, the enzyme water activity curve is available, this methodology provides the total water that must be added to the system (enzyme plus solvent) so that a specific water activity can be obtained. The same methodology can also be applied to predict the effect of the total water content of the system (initial or initial plus produced) on the water activity values. It is shown that: (a) for esterification reactions taking place in hydrophobic organic solvents, the produced water can lead to a substantial change in water activity, but not for less hydrophobic solvents; (b) introduction of dry CO2 into a system, pre-equilibrated to a certain water activity at atmospheric pressure, can lead to a substantial decrease in the water activity especially at temperatures just above the critical one of the solvent and pressures larger than that.	en
heal.publisher	HARWOOD ACAD PUBL GMBH	en
heal.journalName	Biocatalysis and Biotransformation	en
dc.identifier.doi	10.3109/10242420109003639	en
dc.identifier.isi	ISI:000170173400002	en
dc.identifier.volume	19	en
dc.identifier.issue	2	en
dc.identifier.spage	99	en
dc.identifier.epage	118	en