Sequential enzyme reactions

Easterby proposed a generalized theory of the transition time for sequential enzyme reactions where the steady-state production of product is preceded by a lag period or transition time during which the intermediates of the sequence are accumulating. He found that if a steady state is eventually reached, the magnitude of this lag may be calculated, even when the differentiation equations describing the process have no analytical solution. The calculation may be made for simple systems in which the enzymes obey Michaehs-Menten kinetics or for more complex pathways in which intermediates act as modifiers of the enzymes. The transition time associated with each intermediate in the sequence is given by the ratio of the appropriate steady-state intermediate concentration to the steady-state flux. The theory is also applicable to the transition between steady states produced by flux changes. Apphcation of the theory to coupled enzyme assays makes it possible to define the minimum requirements for successful operation of a coupled assay. The theory can be extended to deal with sequences in which the enzyme concentration exceeds substrate concentration. 

The application of immobilized model systems for investigation of the kinetics of sequential enzyme reactions has been reviewed. 

Genencor s proprietary concept of continuous biocatalytic systems using sequential enzyme reactions for processing the cellulosic component of biomass to biochemicals minimizes these problems. This concept addresses issues related to i) substrate inhibition, ii) enzyme inactivation, Hi) cofactor instability, iv) intermediate inhibition, and v) mass transfer limitations and thus overcomes key existing limitations for biomass conversion to industrial chemicals. ... 

The preparations of the 1,2-dinitrate, 1-nitrate, 2-nitrate and 2,5-dinitrate myoinositol derivatives have been described. The preparation of radiolabelled inositol-1-phosphate by way of sequential enzyme reactions on radiolabelled glucose has been reported. ... 

As long as the conditions for reaching a steady state k is large enough) are maintained, its level in terms of intermediate concentration can be varied. This is done by increasing C 2(0) above the lower limit to change the steady state flux. This makes it possible to assay El under conditions of different constant product concentrations and thus obtain information about product inhibition and equilibria. A comprehensive review of equations describing sequential enzyme reactions has been presented by Brooks Suelter (1989). 

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