Enzyme efficacy

Various detergent ingredients may affect the enzyme efficacy strongly. Enzyme activity and stability depend on the pH and temperature of the wash solution, the time of contact of the stained fabric with the enzyme-containing solution, and the presence of builders and bleach. Surfactants, especially the anionics, are of primary importance in lessening enzyme stability. Consequently, an enzyme which is superior to another one in one composition-may become inferior in some other. For instance, medium pH values, and contents of anionic surfactant favor Alcalase, whereas alkalinity and high nonionic surfactant contents favor Esperase, which also withstands sodium perborate better. 

The enzyme efficacy strongly depends on temperature, which affects its dissolution rate, its activity, and its stability in the washing bath. The dissolution is, of course, faster at higher temperature [49] ... 

The enzyme efficacy also depends on the nature of the fabric, which determines the fiber hydrophilicity and the strength of the soil-fiber interaction. Moreover, the accessibility of the soil depends on the yarn density and on its location outside or inside the fiber. 

These effects must, however, be carefully analyzed, as artifacts easily lead to erroneous conclusions. For instance, in a long-term usage carried out in the mid-seventies in Europe, Alcalase and Esperase broke even on synthetics, whereas Esperase won for cotton. That superiority, however, did not result from a true effect of the fabric but from the temperature effect on the enzyme efficacy, as cotton was usually washed at a higher temperature (60-90°C) than synthetics (40-60°C). 

Keeping the pH near neutral in the detergent formulation also increases the enzyme stability. A pH increase upon dilution both increases the enzyme efficacy and the detergency of other formulation ingredients [71]. 

The membrane enzyme luciferase, responsible for light emission in fireflies, is sensitive to anesthetics (20,21), and the concentrations of inhalational agents which inhibit luciferase are the same as those which cause general anesthesia. Studies of various classes of inhalational agents and luciferase demonstrated that above a certain chain length in a homologous series, a point is reached where higher members are not anesthetic. The same cut-off effect in efficacy is observed in anesthesia (22). This effect is not explainable by Hpid theory. 

It is essential to maintain high, maximal velocities of enzymatic activity for the attainment of optimal therapeutic efficacy. As a general rule, only enzymes whose MichaeHs-Menten constants He between 1—100 ]lM are effective as dmgs (16) because most substrates for therapeutically useful enzymes are present ia body fluids and cells at suhmillimolar concentrations. 

L-Asparaginase is used for the treatment of appropriate lymphoproliferative disorders in two clinical trials, L-asparaginase was used in combination with chemotherapy for the treatment of refractory acute nonlymphocytic leukemia in children (24) and adults (25). A moderate efficacy, attributable to the enzyme, was demonstrated in both trials. 

Streptokinase has an initial plasma half-life (/ 2 of 18 min, and a P half-life of 83 min (73) it is well recognized that the thrombolytic efficacy of the enzyme decreases as the age of the thrombus increases thus, thrombolysis is significantly decreased when therapy is initiated more than three hours after an occlusion (74). 

The thrombolytic efficacy of streptokinase treatment may be compromised by the presence of antibodies to the enzyme in the patient s blood. 

The active metabolite of leflunomide, the ring-opened drug A771726, inhibits dihydroorotate dehydrogenase (DHOD) which is the key enzyme of the de novo pyrimidine synthesis. Inhibition of synthesis stops proliferation of activated lymphocytes. The leflunomide derivative FK778 which shows similar therapeutic efficacy but shorter half-life is investigated in clinical trials. 

---