Enzyme Activity In Presence Research Articles

Light dependent increase of triosephosphate dehydrogenase in pea leaves.

Data from 3 lines of investigation were presented indicating that chlorophyll is not necessary for the increase in the triphosphopyridine nucleotide-requiring triosephosphate dehydrogenase accompanying the illumination of etiolated pea plants. These include A) the kinetics of the development of chlorophyll and enzyme activity, B) the presence of enzyme activity in leaves grown in the dark on normal plants and C) the high specific enzyme activity in leaves of a chlorophyll-less mutant. It was also shown that the light-initiated increase of enzyme activity continues for several days after removal from the light and that illumination with far-red light before the dark period inhibited, but did not abolish, this increase. The ability of green plants to continue to produce the enzyme in the dark was eventually lost with time, for after 7 days in the dark a stimulation in leaf protein formation was not accompanied by an increase in enzyme activity.

Dialysis of Small Specimens in Batches

IN experiments involving the separation of proteins, it is often necessary to dialyse large numbers of samples, each of a small volume. (Salt fractionation of enzymes, when the fractions cannot be assayed for enzymatic activity in presence of the salt, is a case in point.) Dialysis becomes tedious if large numbers of 1- or 2-ml. samples have to be transferred to dialysis bags from the centrifuge tubes used for precipitating and centrifuging down the fractions, and then have to be recovered more or less quantitatively.