High Value Fermentation Products, Volume 1

Chapter 14Production of Yeast Derived Microsomal Human CYP450 Enzymes (Sacchrosomes) in High Yields, and Activities Superior to Commercially Available Microsomal Enzymes

Ibidapo Stephen Williams and Bhabatosh Chaudhuri^*

CYP Design Ltd, The Innovation Centre, 49 Oxford Street, Leicester, LE1 5XY, UK

*Corresponding author: [e-mail]

Abstract

Human CYP450 enzymes, naturally bound to livers’ endoplasmic reticular (ER) membranes, are used for drug-metabolism studies and commercially produced from genetically engineered insect/bacterial cells. They are temperature-labile and must be stored at -80 °C. Unlike insect/bacterial cells, the intracellular environment of baker’s yeast and human cells is similar. Here we show that six major human liver CYP enzymes (1A2/2C9/2C19/2D6/2E1/3A4), isolated from baker’s yeast as ER-bound microsomes (Sacchrosomes™) in yields of 120–325 nmol/L, are 0.5–25 fold more active than commercial enzymes. IC₅₀ values for Sacchrosome inhibition by known CYP inhibitors are similar to those published using human-liver-microsomes (HLMs). Moreover, freeze-dried Sacchrosomes can be stored at +21 °C for at least 6 months without losing enzymatic activity. These results suggest that yeast cells, cheap and easy to grow, could provide an ideal environment for bulk production of highly active human CYP microsomal enzymes so that they could be used more widely than they are now.

Keywords: Baker’s yeast, human cytochrome P450, CYP450 activity, drug metabolism, ...