Page 107 - Demo 1

Beyond the opmal temperature the enzyme structure begins to break down,
affecng the chemical bonds in the acve site and making them less well-suited
to bind substrates.

Substrate Concentraon

The rate of an enzyme-catalyzed reacon also depends on
the concentraon of substrate. For a given enzyme concentraon, the
rate of reacon increases with
increasing substrate
concentraon up to a point, above
which any further increase in substrate
concentraon produces no significant
change in reacon rate. This is because
the acve sites of the enzyme molecules
at any given moment are virtually
saturated with substrate. The enzyme-
substrate complex has to
dissociate before the acve sites are
free to accommodate more substrate.
Provided that the substrate concentraon is high and that temperature and pH
are kept constant, the rate of reacon is proporonal to the enzyme
concentraon.

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