Bessie B. Cook

The determination of certain properties of β-lactoglobulin and its lactose derivatives

Abstract In an attempt to elucidate further the browning reaction in milk, two purified components, crystalline β -lactoglobulin and lactose, have been reacted in solution. This reaction set in immediately at 53°C., as shown by the rapid formation of fluorescent products. The increase in optical density, depicting further steps in the browning reaction, showed a short lag period and then rapid development. With these changes in physical properties were associated a decrease in free amino and basic groups and a resistance to enzymic digestion, particularly in regard to the release of lysine. In order to ascertain the possible role of cysteine in this reaction, the thiol groups were determined. Native β -lactoglobulin was found to contain 0.50 sulfhydryl groups/10 4 g. or 2 groups/mole. A reduction of these groups was observed in the control experiment and no further destruction was noted upon browning.

Cataract- and Dermatitis-Producing Nutritional Factors

Cataract has been produced experimentally by parathyroidectomy, pancreatectomy, vitamin G-low diets, 1 lactose-rich 2 and galactose-containing 3 diets. In human subjects dinitrophenol has been reported as likewise cataract-producing. The difficulty of reconciling these diverse precipitating conditions is great, and in fact may not be possible. However, it is interesting to speculate upon the possible interrelation of the 2 obviously nutritional factors, vitamin G (B2) and lactose. The delay in, or interference with, complete absorption accompanying the presence of large amounts of lactose or galactose in the intestine and the frequent gastro-intestinal absorption difficulties in clinical conditions associated with vitamin G deficiency, for example pellagra, pernicious anemia and sprue, offer a possible common avenue of attack upon the problem. The present study was planned to test the bearing of such absorption-disturbances upon the production of cataract, of dermatitis and of growth-abnormality. The diets used are of the usual vitamin-testing type containing casein purified by repeated extraction with 60% alcohol and varying chiefly in the carbohydrate fraction and in the supplement.