, 1995 and Kapoor et al., 2012). For example, screening of commercial preparations of lipases for obtaining the best conversion of oil to biodiesel is quite common (Nelson et al., 1996, Shah et al., 2004 and Shah and Gupta, 2007b). Similarly,

lipases from different sources are increasingly screened for obtaining the best yield in a promiscuous reaction (Lai et al., 2010 and Li et al., 2008). Invariably, initial rates are compared before the choice for the best biocatalyst is made. This may not necessarily be the best choice as initial rates are just that: rates yet to be affected by multiple factors which start operating as the reaction progresses selleck compound (see later for a discussion on importance of complete progress curve). However, comparing either initial rates (which has “per mg” of the biocatalyst as a part of its units) or even the conversions and yields from two different commercial preparations is actually comparing apples and pears! Foresti and Ferreira (2005a) have discussed this issue in the context of lipase-catalyzed reactions. However, the points raised have wider implications particularly in the context of industrial buy SCH772984 enzymology. • Strictly speaking, the terms “enzyme”, “lipase” and “protein” are not interchangeable. The first one is the total weight of the preparation; “protein” is the total amount of protein in the preparation on a weight basis, this can constitute

a very small percentage of the total weight of the “enzyme”. Lipase, of Vildagliptin course, refers to the amount of pure lipase present in the “enzyme”. This often is an unknown quantity in a commercial enzyme preparation. It is, however, a common practice to use the term lipase for the total amount of protein, that is, the amount of impure lipase. Often, one has to rely upon the context to understand what may be meant. Foresti and Ferreira (2005a,b) have outlined how to avoid some of the above pitfalls by careful considerations while designing the experiments. The efficiency of the enzymes is generally expressed

in terms of initial rates. This is more or less the norm when the workers describe a more efficient biocatalyst design or formulation for catalysis in low-water media (Straathof and Adlercreutz, 2000 and Vulfson et al., 2001). Engineered enzymes by site-directed mutagenesis or directed evolution are also generally evaluated in terms of initial rates. The initial rate, by definition, is the early initial and linear portion of product concentration vs. time graph. In aqueous buffers, this linearity usually persists to at least till 5% conversion has taken place (Purich, 2010). In low-water media, conversions are much slower and one can observe linearity up to 20–30% of the conversion (Solanki and Gupta, 2008 and Solanki and Gupta, 2011). Reactions which display a lag phase or a burst phase pose problems in accurate estimation of the initial rates.