Enthalpic and entropic contributions in the transesterification of sucrose: computational study of lipases and subtilisin.
Transesterification of sucrose with fatty acids catalyzed by subtilisin Carlsberg occurs with regioselectivity that is different from that in lipases. Thermomyces lanuginosus lipase (TlL) and Candida antarctica lipase B (CALB) catalyze synthesis at positions 6 and 6', with differing abilities, while subtilisin catalysis leads to the 1'-acylated sucrose. The catalytic machinery in lipases is approximately mirrored in subtilisins but different pocket morphologies including size, shape, and rearrangement of the catalytic elements underlies the differing regioselectivities. The thermodynamic consequences of these differences on the above reactions have been explored systematically using computational methods, determining the free energies of interaction of the putative transition-state adducts. Analysis of the conformers with the lowest transition state energies (protein-ligand interactions and vibrational entropy contributions) indicates that enthalpic factors control specificities in lipases while entropic factors are more important in subtilisin.
Fuentes
Gloria
G
Departamento de Biocatálisis, Instituto de Catálisis, CSIC, Cantoblanco, 28049 Madrid, Spain.
Ballesteros
Antonio
A
Verma
Chandra S
CS
D001665:Binding Sites; D003198:Computer Simulation; D019277:Entropy; D004951:Esterification; D005656:Fungal Proteins; D008049:Lipase / Q000737:chemistry / Q000378:metabolism; D008958:Models, Molecular; D015394:Molecular Structure; D017434:Protein Structure, Tertiary; D020860:Subtilisin / Q000737:chemistry / Q000378:metabolism; D013395:Sucrose / Q000737:chemistry*; D013816:Thermodynamics
D005656:Fungal Proteins; D013395:Sucrose; D008049:Lipase; C431349:lipase B, Candida antarctica; D020860:Subtilisin