[Identification and properties of 2 forms of plant phospholipase D]. / Obnaruzhenie i svoistva dvukh form fosfolipazy D rastenii.

Effect of different factors (pH, temperature etc.) on the activity of phospholipase D is studied. It is found that plant phospholipase D has two forms: thermolabile (D1) and thermostable (Ds). Both forms are shown to differ in some characteristics (pH optimum, temperature optimum, calcium ions activation, activator effect, kinetic parameters, thermostavility). The contradictive literature data on phospholipase D properties are suggested to be due to the existence of two enzyme forms.

[Immobilized phospholipase D]. / Immobilizovannaia fosfolipaza D

Conditions of phospholipase D adsorption on silica gels have been studied. The immobilized phospholipase D is shown to differ from the soluble form in thermostability, pH optima and activation conditions. A question is discussed as to the connection of the use of activators and the adsorption immobilization. It is assumed that phospholipase D belongs to enzymes, functioning only in the immobilized state.

[Several properties of cotton seed phospholipase D]. / Nekotorye svoistva fosfolipazy D iz semian khlopchatnika

Properties of phospholipase D were studied using purified enzyme preparation from cotton seeds. The results obtained differ from those described in literature. It has been shown that the promoting action is exerted not only by diethyl ether and sodium dodecyl sulfate commonly used as initiators, but by some organic solvents in the presence of calcium ions as well. The activation of phospholipase D is also possible in the presence of other bivalent cations, e.g. Sr2+, Ba2+, Mn2+ and Mg2+. It is assumed that the enzyme activation occurs only in the presence of the stable heterogenous system: water-soluble enzyme--phospholipid--non-aqueous phase. Another important factor is the type of modification of the surface of the phospholipid phase, responsible for the enzyme adsorption and its subsequent activation. Comparison is made of the properties of phospholipases D isolated from cotton seeds and some other sources.

[Activators of phospholipase D]. / Ob aktivatorakh fosfolipazy D

The activation of phospholipase D from cotton seeds by diethyl ester, sodium dodecyl sulphate and silica gel during egg lecithin hydrolysis was investigated. In the presence of silica gel the enzymic reaction developed without calcium ions. The data were accumulated indicating that the main characteristics of phospholipase D obtained from the in vitro study of the enzymic hydrolysis of phospholipids depended at large on the activator applied.