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The enzyme kinetics for plasmalogenase have been analyzed on a developmental basis and correlated with the presence of ethanolamine plasmalogen (1-alkyl,1'-enyl,2-acyl-sn-glycerol-3-phosphoryl-ethanolamine) in dystrophic chicken erythrocyte membranes. At day 15 ex ovo, both dystrophic (Line 413) and normal (Line 412) chicken erythrocyte enriched microsomal preparations manifest high Km forms of plasmalogenase. However, with time, the Km of this enzyme from normal erythrocyte preparations drops significantly whereas the Km of the enzyme from dystrophic preparations remains high. This observation may account for elevated concentrations of plasmalogen observed in dystrophic chicken tissues.

1. Three purported zinc metalloenzymes have been investigated from cell cultures of the fathead minnow (Pimephales promelas). 2. With the addition of increasingly higher concentrations of zinc to the tissue culture medium, the specific activity of LDH increased. 3. The results with MDH were equivocal. 4. The specific activity of alkaline phosphatase decreased in the presence of increasing amounts of zinc in the growth medium. 5. Zinc exogenously added to the LDH enzyme assay did not alter the LDH enzyme activity of cells grown without zinc.