Lysozyme activation volume

Figure 2. pH dependence of native arid ozonized lysozyme activity. Volumes of 1.0 ml of O.IM buffer containing 1.91 mg lysozyme were exposed to a gas stream of Oj/O at a flow rate of 20 ml/min for 8 min. Ozone delivery was 1.5 nmoles/min. Samples were assayed at the different pHs as described in Materials and Methods. 

Flarada M. 1977. Photochemical smog and tear fluid. [Effects [of smog] on pH, volume, and lysozyme activity of tear fluid.] Nipon Ganka Gakkai Zasshi 81.215- 286. (Japanese)... 

Some recent investigations have failed to substantiate earlier claims that NAA are effective as a result of, helr ability to stabilize lysosome membranes. It has been concluded, however, that lysosome membrane stability is very much dependent on experimental conditions and that in vitro methods using rat liver lysosomes are not sufficient for studying the effect of antiinflammatory drugs. Increased lysosomal enzyme activity in homogenates of rat paws paralleled increases in paw volume in rats with adjuvant-induced arthritis. Oral administration of phenylbutazone arrested Increases in both enzyme activity and paw edema. Above normal lysozyme activity was found in the serum and synovial fluid of a signlficent proportion of patients with RA. ... 

Activity is measured by the procedure of Shugar.21 To 2.9-ml cuvettes (1 cm path length), diluted lysozyme (ranging from 0.1 to 0.5 nM) and antibody (ranging from 0.013 to 50 nM) are added to 66 mM potassium phosphate buffer, pH 6.24, and 0.1% bovine serum albumin (BSA) (w/v) to a volume of 900 fil. The solutions are kept at 25° for 1 hr to allow the lysozyme-antibody complexes to come to equilibrium. The activity assays are initiated by the addition of 100 pi Micrococcus lysodeikticus (Sigma Chemical Company) cell walls (2 mg/ml in 66 mM potassium phosphate, pH 6.24) to a final A450 of 0.8 -1.0. Cuvettes are wrapped with Parafilm to prevent evaporation, inverted several times to mix, and placed in a Perkin-Elmer, Norwalk, CT) Lambda 4B spectrophotometer. Reactions are monitored by the decrease in A450 for 70 min with a data point collected every minute. 

The fin ax of an enzyme is a measure of how fast the reaction it catalyzes can proceed once the enzyme-substrate complex is formed. This is related to the turnover numberthe number of substrate molecules converted into product per active site at very high substrate concentration. Turnover numbers vary from very high (e.g., 600,000 sec-1 for carbonic anhydrase) to relatively slow (e.g., 0.5 sec-1 for lysozyme). Another name for turnover number is cat, which is related to Em ax and the total enzyme concentration, [E] (measured as number of active sites per unit volume of solution), as follows Em ax = Acat x [E],... 

In addition, it was demonstrated [72] that the secondary structure of an enzymic protein is essential to protein s catalytic activity. Also, it was shown that this structure remains intact in neat organic solvents [72]. The molecules, however, are denatured in water-organic solvent mixtures. The ot-helix of lysozyme, for instance, when the enzyme is crystalline or dissolved in neat acetonitrile, 35% of it is an a-helix, but in pure water that value is 23%. In a 60 30 mixture by volume of acetonitrile and water, it is reduced to 13% [72]. 

The size-exclusion protein refolding of lysozyme is relatively unaffected by temperature. Increasing the column temperature from 20 °C to 50 °C results in a decrease in the regained specific activity of 5%, and a decrease in the elution volume of 8 mL (2.3%) [26]. 

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