Comparison of antibody and albumin catalyzed hydrolysis of steroidal p- nitrophenylcarbonates

Sergio Riva, Monica Mendozza, Giacomo Carrea, Panchanon Chattopadhyay, Alfonso Tramontano

Research output: Contribution to journalArticle

7 Scopus citations

Abstract

A monoclonal antibody (MAb) was produced against the p- nitrophenylphosphate derivative of 3α,5β-lithocholic acid, a transition- state analog for hydrolysis of a steroidal p-nitrophenylcarbonate. The indicated reaction was catalyzed by this Ab with kinetic constants k(cat) = 4.0 x 10-2/min and K(m) = 3.3 μM at pH 9.0 and 35°C. The Ab also hydrolyzed the isomeric p-nitrophenylcarbonate of 3β,5β-lithocholic acid with k(cat) = 8.4 x 10-2/min and K(m) = 1.0 μM. Bovine serum albumin (BSA) was found to catalyze the same reactions with similar turnover rates and Michaelis constants of 15 and 14 μM, respectively. Although the BSA- catalyzed reaction was only weakly inhibited by the phosphate ester TSA (IC50 ca. 40 μM), the Ab-catalyzed reaction was completely inhibited at less than 1 μM of the TSA. The relative rates and efficiencies of the MAb- catalyzed and BSA-catalyzed reactions are discussed in the context of the hydrophobic sites and intrinsic reactivity of the protein surfaces, and the induction of groups on the Ab to enhance the enzymatic function.

Original languageEnglish (US)
Pages (from-to)33-44
Number of pages12
JournalApplied Biochemistry and Biotechnology - Part A Enzyme Engineering and Biotechnology
Volume75
Issue number1
StatePublished - 1998
Externally publishedYes

Keywords

  • Albumin
  • Carbonate
  • Catalytic antibody
  • Phosphate hapten
  • Steroid

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Biochemistry
  • Biotechnology
  • Bioengineering

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