Biomedical Engineering Reference
In-Depth Information
fulfilment of the requirements mentioned above. Later, several papers were
published that developed the methodology for the characterization of the cata-
lytic properties of immobilized enzymes [26-33]. Flow microcalorimetry pro-
ved to be very practical and versatile technique.The principal advantage of FMC
is the integration in one step of the enzyme reaction and monitoring of the reac-
tion course.In spite of its evident advantages,enzyme flow microcalorimetry is
not very widely used. One of the reasons for this may be the relatively wide
dispersion of published data on possible applications. Another reason is the
nature of calorimetric measurement: The thermometric measurement does not
provide direct information on changes in the concentration of the reacting com-
pounds; therefore the results of the measurement need to be converted in order
to estimate the reaction rate. The authors of this review believe that the broad
application of FMC in routine analysis of the properties of immobilized bio-
catalysts can be facilitated by providing systematic information about the
methodology required for manipulation of this technique.In this review,simple
mathematical models useful for FMC data treatment are presented, and
methods for facilitating the interconversion of thermometric and rate data are
presented.Several examples of the application of the technique are provided.
2
Equipment and Procedure
Figure 1 depicts the experimental arrangement that is in regular use in our labo-
ratories for the investigation of the properties of IBM by flow microcalorimetry.
The main functional part of the equipment is the flow microcalorimeter 3300
Thermal Assay Probe (Advanced Biosensor Technology AB Lund, Sweden). It
consists of a thermostated block containing a small column packed with an IMB
(FMC unit), probes equipped with thermistor sensors connected to a measure-
ment and control unit, i.e., a Wheatstone bridge and temperature control. The
analog signal provided by FMC unit is digitized and registered by a personal
computer.The system is equipped with a peristaltic pump and a switching valve
that selects between an open mode (all material from the column output is
wasted) and a closed mode (total flow circulation is achieved). The principle of
measurement is registration of the temperature change induced by the heat of
Fig. 1. Experimental setup for the enzyme flow microcalorimetry
 
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