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A theoretical equation describing the time evolution of the concentration of a selected range of substrate molecular weights in depolymerization processes mediated by single‐attack mechanism endo ‐enzymes
Author(s) -
Sendra José M.,
Carbonell José V.
Publication year - 1998
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/(sici)1097-0290(19980220)57:4<387::aid-bit2>3.0.co;2-i
Subject(s) - depolymerization , substrate (aquarium) , chemistry , michaelis–menten kinetics , molecular mass , fluorescence , kinetics , glucanase , analytical chemistry (journal) , enzyme , stereochemistry , chromatography , enzyme assay , biochemistry , organic chemistry , physics , biology , ecology , quantum mechanics
Monitoring the time evolution of the concentration of a selected range of molecular weights of substrate, referred to as “detectable” substrate, has been used to determine endo ‐enzymic activities in polysaccharide depolymerizing processes. In the methodologies based on the use of dye‐labeled substrates, the “detectable” substrate extends from a given molecular weight threshold downward. On the contrary, in the fluorescent probe‐flow injection analysis methodology, initially developed to determine (1 → 3)‐(1 → 4)‐β‐ d ‐glucanase activities, the “detectable” substrate extends from a given molecular weight threshold upward. Assuming that the time evolution of the molecular weight distribution of the substrate follows the most probable distribution (the enzymic attack is random and its mechanism is single attack), a theoretical equation describing the time evolution of the concentration of “detectable” substrate (from a given molecular weight threshold upward or downward) has been deduced. This equation, W d = W o · (1 + α t ) · e −α t , where W d is the concentration of “detectable” substrate, W o is the initial concentration of the substrate, t is the depolymerization time, and α is a parameter correlated through a hyperbola with the initial concentrations of enzyme and substrate and the Michaelis–Menten constant, K m , has been tested against different (1 → 3)‐(1 → 4)‐β‐ d ‐glucan/(1 → 3)‐(1 → 4)‐β‐ d ‐glucanase systems using the fluorescent probe‐flow injection analysis methodology and Calcofluor as the fluorescent probe. The most important predictions of the theoretical equation, which allow accurate determination of both endo ‐enzymic activities and kinetic constants, have been experimentally confirmed. ©1998 John Wiley & Sons, Inc. Biotechnol Bioeng 57: 387‐393, 1998.