A Chemical Study of Leaf Cell Cytoplasm

Abstract

The proteins of leaf cytoplasm can be separated into 2 fractions (A) ''combined'' proteins, which are in some loose combination with substances soluble in alcohol, and (B) ''soluble'' proteins, which are free and pass fairly readily into solution when the cytoplasmic gel is ground with water. The soluble proteins of a large number of different leaves have been investigated; preparations sufficiently pure for chemical analysis have been made only from leaves of herbaceous plants having a leaf cell sap which is alkaline with respect to the iso-electric point of the proteins. The proteins are glutelins, and although they may be mixtures, their chemical properties are very similar. All have an isoelectric range from p H 4.0 to p H 5.0 in which their solubility is at a minimum.