title: Adding an appropriate amino acid during crosslinking results in more stable crosslinked enzyme aggregates.
abstract: Carrier free immobilization, especially crosslinked enzyme aggregates (CLEAs), has become an important design for biocatalysis in several areas. Adding amino acids during formation of CLEAs was found to give biocatalysts more stable at 55 °C and in the presence of 60% acetonitrile. The half-lives of CLEAs prepared with and without Arg addition were 21 and 15 h (subtilisin) and 4 and 1.6 h (α-chymotrypsin) at 55 °C, respectively. The corresponding half-lives during acetonitrile presence were 4.1 and 3.0 h (subtilisin) and 39 and 22 min (α-chymotrypsin), respectively. CLEAs made with Arg had higher percentages of alpha helix. CLEAs made by adding Lys, Ala, or Asp also were more stable. In the case of Thermomyces lanuginosus lipase (TLL), CLEA with Ala was even more stable than CLEA with Arg. The addition of a suitable amino acid, thus, enhances CLEA stabilities. The results are discussed in the light of earlier results on chemical modification of proteins and the observation that the Arg/Lys ratio is invariably high in the case of enzymes from thermophiles.
authors.affiliation: Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India.
authors.forename: Joyeeta
authors.initials: J
authors.lastname: Mukherjee
authors.affiliation: Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India.
authors.forename: Abir Baran
authors.initials: AB
authors.lastname: Majumder
authors.affiliation: Department of Biochemical Engineering and Biotechnology, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India. Electronic address: munishwar48@yahoo.co.uk.
authors.forename: Munishwar Nath
authors.initials: MN
authors.lastname: Gupta
mesh_terms: D000596:Amino Acids / Q000737:chemistry / Q000378:metabolism*; D001203:Ascomycota / Q000201:enzymology; D003432:Cross-Linking Reagents / Q000737:chemistry / Q000378:metabolism*; D004800:Enzymes, Immobilized / Q000737:chemistry / Q000378:metabolism; D008049:Lipase / Q000737:chemistry / Q000378:metabolism*; D066329:Protein Aggregates
chemical_list: D000596:Amino Acids; D003432:Cross-Linking Reagents; D004800:Enzymes, Immobilized; D066329:Protein Aggregates; D008049:Lipase
keywords: Crosslinked enzyme aggregates (CLEAs); Enzyme stabilization; Enzymes in detergents; Enzymes in organic solvents; Lipases; Subtilisin