Wheat Germ Lipase Research Articles

EFFECT OF WHEAT GERM LIPASE ON HUMAN CELLS TRANSFORMED IN VITRO BY SIMIAN VIRUS 40.

Selective inhibition by preparations of wheat-germ lipase (WGL) was demonstrated for human cells transformed in vitro by SV40. This inhibition was reflected in the number and size of colonies formed, as well as in total cell growth, in a medium containing 0.01% of WGL. The presence of WGL in the medium of SV40-infected human diploid cells failed, however, to delay or inhibit the formation of transformed cell centers. Cells transformed in medium containing WGL appeared to multiply no less than control transformed cells during the first 4 weeks after transformation. They then began to clump, and to reveal reduced growth capabilities which led to early death of the cultures. The inhibitory action of WGL on transformed cells was not destroyed by heating the preparation at 60°C, a procedure which inactivated its esterase activity for triacetin.

Cytological studies of the entry of enzymes into cells in tissue culture

1. 1. The uptake of enzymes under in vitro conditions in a selection of normal and malignant cell types has been investigated using chymotrypsin, a wheatgerm lipase preparation, and cytotoxic aliesterases isolated by column chromatography from the latter preparation. 2. 2. Whereas chymotrypsin was not taken up by pinocytosis, uptake of the wheat-germ enzymes was very active in all the cell types studied, suggesting that pinocytosis was stimulated by a specific interaction of the wheat-germ enzymes with the cell. 3. 3. An affinity of the wheat-germ enzymes for the cell membrane has been demonstrated, and possible explanations are considered.

Interaction of enzymes with normal and tumour cells.

WHEAT germ lipase (Worthington) has been shown1 to reduce the adhesion of washed mouse ascites cells to glass. This was considered to be due to the adsorption of the enzyme on to the cell surface. The same lipase preparation has also been found2 to inhibit the growth of hamster kidney tumour cells in tissue culture at certain concentrations (0.01–0.1 per cent), without inhibiting growth in vitro of hamster normal kidney epithelial cells from which the tumour was derived.

Effects of quinidine on triacetin utilizing activity of pancreas.

SummaryPancreatic TUA is reversibly inhibited by quinidine and quinine. Quinidine inhibition can be reversed by triacetin to about 70%; however, protection by triacetin could not be demonstrated. Quinidine and related compounds are effective as inhibitors of pancreatic triacetin utilizing activity in the following order: quinine sulfate > quinidine sulfate; quinidine gluconate> quinidine sulfate. To the extent tested, the same relationship holds for wheat germ lipase using triacetin as substrate. In the wheat germ lipase system the Ki for quinidine sulfate = 1 × 103, and the Ki for quinine sulfate = 5.7 × 104. Heparin inhibits the pancreatic TUA in presence or absence of quinidine. Metals, such as Cu+2 and Mg−2 inhibit this system and Cu−2 increases quinidine inhibition but Mg−2 does not. Fe−3 does not inhibit the system or interfere with quinidine inhibition. EDTA inhibits this system by 70% at a level of 10−3M. This inhibition is partially reversed by Ca+2 ions which also markedly stimulate TUA activity...

The enzymatic hydrolysis and tissue oxidation of fatty acid esters of sucrose

SummaryVarious preparations of sucrose fatty acid esters were hydrolyzed by wheat germ or pancreatic lipase, pancreatin, pancreatic juice, α‐amylase, invertase, or liver homogenates to yield sucrose and free fatty acids as products. The greatest activity was observed with the liver homogenate.None of the enzymes studied cleaved the glycosidic linkage as indicated by the lack of appearance of reducing groups and by paper chromatography of the products.The greatest hydrolysis by pancreatic lipase was observed with sucrose esters having a greater preponderance of unsaturated fatty acids, namely, sucrose trilinoleate, sucrose dilinoleate, sucrose tetralinoleate, and “Sequol 260” (69% unsaturated fatty acids).Sodium taurocholate was required for hydrolysis by pancreatic lipase but not by wheat germ lipase. Sucrose ester was inhibitory to the hydrolysis of triolein by all lipolytic preparations. Tetra‐ethyl pyrophosphate and cupric ions were not inhibitory to the hydrolysis of sucrose ester.Sucrose fatty acid esters supported respiration by rat liver homogenates and to a much lesser extent by rat intestinal mucosa. The rate of oxidation was greater than that observed with sucrose and the corresponding fatty acid. The greatest activity was observed with esters of fatty acids having a greater preponderance of unsaturated fatty acids, namely, “Sequol 260,” sucrose di‐, tri‐, and tetralinoleate.

The effect of substituents on the hydrolysis of phenyl acetate by wheat germ lipase

1. 1. Substituted phenyl acetates have been studied as substrates for wheat germ lipase. 2. 2. The enzymatically catalyzed hydrolysis of these substrates follows the usual Michaelis-Menten formulation. 3. 3. A mechanism for the enzymatic hydrolysis is proposed, and observed k 3 E 0 ( Vmax) values and calculated k 1 E 0 values are correlated with this mechanism.