Molecular activity of enzymes

The turnover number of an enzyme, is a measure of its maximal catalytic activity, is defined as the number of substrate molecules converted into product per enzyme molecule per unit time when the enzyme is saturated with substrate. The turnover number is also referred to as the molecular activity of the enzyme. For the simple Michaelis-Menten reaction (14.9) under conditions of initial velocity measurements, Provided the concentration of... 

Attempts have also been made to exploit the relatively high molecular activity of cod trypsin at low temperatures by incorporating the enzyme into herring "fermentations that proceed at 10°C. The preparation of brine-fermented round herring (matjes) is limited to certain seasons because of the balance of digestive enzymes in the fish at this time. Other studies have indicated that proteinases are important components in matje fermentation 41),... 

The regulation of the activity of enzymes by the binding of effector molecules is a ubiquitous and general principle for the fine timing and control of metabolic activity. Effector molecules are often low molecular weight organic compounds. Proteins and metal ions can also exercise the function of effectors. The effector molecules bind specifically to the enzymes and the binding results in inhibition or stimulation of enzymatic activity. 

Finally, as previously emphasized, solid/gas biocatalysis, because of its peculiarities, leads to a more accurate approach to the study of the effect of the microenvironment on enzymatic activity and stability. This allows access to intrinsic parameters of enzymes, thus providing a better molecular understanding of enzyme catalysis in general. 

Albeit the substantial progress in the bioelectrochemical activation of enzymes, one could identify two important future challenges in the field (i) The active relay units wiring the redox centers of the enzymes with the electrodes could be generated by photoinduced electron transfer. This could pave the way to the photochemical wiring of enzymes and to the development of photobiofuel cells, (ii) DNA scaffolds provide unique templates for the ordered self-assembly of molecular or biomolecular units through dictated hybridization. The ordering of relay units and enzymes, or of relay units photosystems, on DNA templates associated with electrodes may yield attractive new supramolecular nanostructures for bioelectronics and optobioelec tronic s. 

The interesting suggestion has been made (61) that the unusually high molecular activity of extracellular /3-lactamases (Table II) may possibly compensate for the dilution of the secreted enzyme in the growth medium. 

The molecular activity of an enzyme is the number of substrate molecules transformed in 1 min by one enzyme molecule under optimal conditions of temperature and pH. 

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