Monday, April 30, 2007

Using activity as a basis for pricing cellulase and other enzymes

Robert D. Tanner1, Elizabeth M. R. Ferguson2, and Chris C. Stowers1. (1) Chemical Engineering, Vanderbilt University, VU Station B 351604, Nashville, TN 37235, (2) Pediatrics Department / Judith B Ratner MD Office, George Washington University, 2150 Pennsylvania Ave NW, Washington, DC 20016


In this study we will explore whether an objective function, in terms of price, can be developed to establish the price of cellulase and other enzymes.  We will determine the price increase of crude cellulase (in terms of activity per mass) following processing to enhance the  purity and concentration of this protein.

We shall use an objective function comprised of measurable purification process responses as our pricing model.  That objective function quantifies the tradeoff between the maximization of the enzyme concentration in a foam fractionation process and minimizing the loss of enzyme mass and enzyme concentration in that process. The proposed pricing model is:

Φ = (AR)a (MR)b (ER)c

                              where        AR = activity recovery = Afoam/Ai

                                               MR = mass recovery = Mfoam/Mi

ER = enrichment recovery = Cfoam/Ci

This approach to the development of price-based processing, Δp, or Φ,   the intermediate purity enzyme processing price, can result in the enhancement of product price at each processing step by selecting the control variables at that step which can maximize the respective Φ.  In a foam-fractionation process, in particular, these control parameters  are typically the pH and the foaming-gas superficial velocity.

We shall compare the fitted catalog values of a  and c for cellulase with other industrial enzymes to determine whether there are general trends and quantitative similarities between classes of enzymes.