Immobilization and stabilization of a bimolecular aggregate of the lipase from Pseudomonas fluorescens by multipoint covalent attachment

The soluble lipase from Pseudomonas fluorescens (PFL) forms bimolecular aggregates in which the hydrophobic active centers of the enzyme monomers are in close contact. This bimolecular aggregate could be immobilized by multipoint covalent linkages on glyoxyl supports at pH 8.5. The monomer of PFL obtained by incubation of the soluble enzyme in the presence of detergent (0.5% TRITON X-100) could not be immobilized under these conditions. The bimolecular aggregate has two amino terminal residues in the same plane. A further incubation of the immobilized derivative under more alkaline conditions (e.g., pH 10.5) allows a further multipoint attachment of lysine (Lys) residues located in the same plane as the amino terminal residues. Monomeric PFL was immobilized at pH 10.5 in the presence of 0.5% TRITON X-100. The properties of both PFL derivatives were compared. In general, the bimolecular derivatives were more active, more selective and more stable both in water and in organic solvents than the monomolecular ones. The bimolecular derivative showed twice the activity and a much higher selectivity (100 versus 20) for the hydrolysis of R,S-2-hydroxy-4-phenylbutyric acid ethyl ester (HPBEt) in aqueous media at pH 5.0 compared to the monomeric derivative. In experiments measuring thermal inactivation at 75 °C, the bimolecular derivative was 5-fold more stable than the monomeric derivative (and 50-fold more stable than a one-point covalently immobilized PFL derivative), and it had a half-life greater than 4 h. In organic solvents (cyclohexane and tert-amyl alcohol), the bimolecular derivative was much more stable and more active than the monomeric derivative in catalyzing the transesterification of olive oil with benzyl alcohol. © 2012 Elsevier Ltd. All rights reserved.

Participation: the view from above

Includes bibliography

Report of the activities of the Commission from June 2004 to December 2005

Includes bibliography

Report of the activities of the Commission from January 2006 to December 2007

Includes bibliography

Four new species of Adenocalymma (Bignoniaceae) and a key to the species from southeastern Brazil

Four new species of Adenocalymma (Bignoniaceae, Bignonieae) from southeastern Brazil are described and illustrated: A. aurantiacum, characterized by dark orange and infundibuliform corolla; A. cinereum, characterized by shrubby habit, greyish inflorescence, infundibuliform corolla, and exserted stamens; A. gibbosum, characterized by gibbous and orange corolla and an inflorescence with dendritic trichomes; and A. sessile, characterized by sessile leaves and gibbous corolla. A discussion on the relationships of the new taxa and a key to all 29 species of Adenocalymma reported from southeastern Brazil are provided. © 2013 The Authors. Nordic Journal of Botany © 2013 Nordic Society Oikos.

Actividades de la Secretaría de la CEPAL relacionadas con las mujeres de América Latina y el Caribe, 1o de junio de 1994-30 de abril de 1996 = Activities of the ECLAC Secretariat relating to the women of Latin America and the Caribbean for the period from 1 June 1994 to 30 April 1996

Incluye Bibliografía

Actividades de la Secretaría de la CEPAL relacionadas con la integración de la mujer en el desarrollo económico y social de América Latina y el Caribe desde el 1o de junio de 1994 hasta el 30 de agosto de 1997 = Activities of the ECLAC Secretariat relating to the integration of women into the economic and social development of Latin America and the Caribbean from 1 June 1994 to 30 August 1997

Incluye Bibliografía

Activities of the ECLAC Secretariat relating to the integration of women into the economic and social development of Latin America and the Caribbean from 1 September 1997 to 30 August 1999

Includes bibliography