Measurements biochemical quantities

Applications of Optochemical Sensors for Measuring Environmental and Biochemical Quantities... 

We can also classify sensors in terms of the quantities that they measure. Physical sensors are used in measuring physical quantities, such as displacement, pressure, and flow, whereas chemical sensors are used to determine the concentration of chemical substances within the host. A subgroup of the chemical sensors that are concerned with sensing the presence and the concentration of biochemical materials... 

An experimentally controlled biochemical or biological system used for the quantitative analysis of perturbations imposed by a test sample (2) a set of operations having the object of determining the value of a quantity. In analytical chemistry, this term is synonymous with measurement. 

For biochemical reactions, the stoichiometric coefficients are usually integer and correspond to the (relative) molecularities in which the reactants enter the reaction. Note that for transport processes, and unless metabolites are measured in absolute quantities, the stoichiometric coefficient also reflect differences in compartmental volumes. 

Enzymes play an important role in biochemical analysis. In biological material—e. g in body fluids—even tiny quantities of an enzyme can be detected by measuring its catalytic activity. However, enzymes are also used as reagents to determine the concentrations of metabolites—e.g., the blood glucose level (C). Most enzymatic analysis procedures use the method of spectrophotometry (A). 

Since the beginning of biochemical investigation enzymes have held a special fascination for chemists and biologists. How can these easily destroyed substances catalyze reactions with such speed and without formation of significant quantities of side products Some enzymes increase the velocity of a single chemical reaction of a specific compound by a factor of as much as 1010. How can a protein do this In this chapter we ll consider both ways of measuring enzymatic activity and basic mechanisms of catalysis. 

Two attributes of synthetic membranes are often applied to the design of analytical devices as a selective barrier, and as a substrate in which chemical or biochemical reactions are performed. In many cases, the membrane helps translate the activity of specific analytes into easily measurable quantities such as electrical potentials or spectrophotomet-ric absorption. 

Calorimeters are instruments used for the direct measurement of heat quantities including heat production rates and heat capacities. Different measurement principles are employed and a very large number of calorimetric designs have been described since the first calorimetric experiments were reported more than 200 years ago. The amount of heat evolved in a chemical reaction is proportional to the amount of material taking part in the reaction and the heat production rate the thermal power, is proportional to the rate of the reaction. Calorimeters can therefore be employed as quantitative analytical instruments and in kinetic investigations, in addition to their use as thermodynamic instruments. Important uses of calorimeters in the medical field are at present in research on the biochemical level and in studies of living cellular systems. Such investigations are often linked to clinical applications but, so far, calorimetric techniques have hardly reached a state where one may call them clinical (analytical) instruments. ... 

The other approach is indirect, namely, to measure not enzymes as such, but their physiological biochemical efficacy. This can be achieved by oral administration of a composite test substance, which is hydrolyzed ( digested ) into its components exclusively by a specific pancreatic enzyme and subsequently absorbed and eliminated by the renal or the respiratory system. Ideally, the urinary excretion/respiratory exhalation of a metabolite of the test substance is proportional to its hydrolysis in the small intestine, which in turn is directly dependent on the quantity of pancreatic enzymes present. 

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