Abstract
Pyruvate decarboxylase (PDC) was prepared from four-day-old pea seedlings by a procedure which involves extraction of plant material with a phosphate buffer, fractionation of the extract with ammonium sulphate, desalting by dialysis or gel filtration on Sephadex G-25 column, chromatography on DEAE cellulose and filtration on Sepharose 4B. The PDC preparation activity 10 000 U g-1 protein was about 600 fold higher than that of the sodium phosphate buffer extract. According to the enzyme behaviour during the gel filtration on different carriers the molecular mass of pea PDS was estimated at about 106. Magnesium ions and thiamine pyrophosphate were found to be coenzymes of PDC. Cofactors can be removed by 48 h dialysis followed by chromatography on DEAE cellulose. Apoenzym is activated optimally with the concentration of cofactors of 0.002 M. Magnesium ions can be replaced in their activation function by ions of Fe2+, Ni2+, Co2+, Zn2+ and Mn2+. Another ions,i.e. Ba2+, Ca2+, Cd2+, Hg2+ and Cu2+ are inactive. Assumption about the relation between the ion diameter and degree of activation is formulated.
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