Male albino rats (Donryu strain) weighing about 120g were kept for sixteen weeks on a purified high-fat (40%) diet containing cholesterol and cholic acid, and the effects of dietary casein and saline on the serum and liver cholesterol levels in the animals were investigated. In addition, the effect of hydrogenated kapok oil was compared with that of butter fat. The following results were obtained.
1) The rat livers in every experimental group were remarkably enlarged and white in appearance (fatty liver). The liver weights per 100g body weight were approximately 15g in the rats fed low casein diet (11%) and 8g in the high casein diet group (31%), respectively.
2) The increase of the dietary casein content from 11 to 31% resulted in a marked decrease in liver total lipid, serum and liver cholesterol levels. In the rat livers in this experiment, cholesterol occupied almost one half of the total liver lipids.
3) When 40% butter fat was substituted for 40% hydrogenated kapok oil, the diet intake was found to be considerably increased. At the same time, the serum and liver cholesterol levels were elevated to some extents.
4) Kidneys, adrenals and thyroid in rats fed the diet containing hydrogenated kapok oil were all remarkably enlarged. However, the weights of these organs were found to be reduced considerably by increasing the content of casein in the diet.
5) Serum and liver cholesterol levels in rats given 1% saline as drinking water were slightly but significantly elevated.
6) Riboflavin levels in livers were markedly low in rats fed low casein diet and also these levels distinctly decreased by the substitution of butter fat for hydrogenated kapok oil in the diet. The levels of riboflavin seemed inversely related to those of cholesterol.

View full abstract

In the liver of rats, fed a thiamine-deficient diet for 15 days, activities of pyruvate dehydrogenase complex (E. C. 1. 2. 4. 1), pyruvate carboxylase (E. C. 6. 4. 1. 1) and L-lactate dehydrogenase (E. C. 1. 1. 1. 27) were determined. Thiamine-deficiency caused a significant lowering of rat liver pyruvate dehydrogenase complex activity which showed one-tenth of that for the control, and the accumulation of pyruvic acid was observed. The activities of pyruvate carboxylase and L-lactate dehydrogenase were increased markedly.

View full abstract

Some investigators^{1) 2)} reported that the enzymes from psychrophilic bacteria are stable without loss of the activity at 0°C or below and a low temperature is favorable for the elaboration of the enzymes.
Pseudomonas fluorescens KM (Kansai Medical School) 361=ATCC (American Type Culture Collection) 13525⁶⁾ (which is able to grow at 0°C) was inoculated in chemically defined rnedium and incubated at 4°C for two months and the relationship between the bacterial growth and the activity of proteolytic enzymes was observed.
Crude proteolytic enzymes, both intracellular and extracellular, would seem to have almost similar characters but some points.
Besides the auther obtained a result suggesting the presence of proteolytic enzymes bound to cellmembrane of psychrophilic bacteria.

View full abstract

The nutritive components and amino acids in the buckwheat flour fractions were determined. These flour fractions were obtained by milling the buckwheat kernel as follows: the first milled product was SF fraction (yield 16%), the second product 1 F (yield 40%), the third product 2 F (yield 40%) and the last product 3 F (yield 3%).
Protein, lipid, ash and phosphate were abundant in the periphery of the endosperm and carbohydrate was in the inner portions. The localization of these components in the buckwheat kernel are similar as in the cereals. Protein content was highest (38.4%) in 2 F fraction and lowest (4.3%) in SF fraction.
These four fractions of the buckwheat flour contained salt-soluble (over 50% content), alkalinesoluble (from 15% to 37% content) and alcohol-soluble proteins (only a few percent content), and in all fractions the salt-soluble proteins were the main proteins and the alcohol-soluble prolamin was the minor one.
The buckwheat flour fractions were found to differ from each other in their amino acid composition. Especially 1 F fraction contained less tyrosine and glutamic acid and more tryptophan, alanine, threonine and valine than those in other flour fractions.
The essential amino acid patterns of the buckwheat flour indicated that the limiting amino acid of these flour fractions was methionine and that the protein value of each fraction was as follows: SF (50), 1 F (62), 2 F (72), 3 F (44). Amino acid composition of 1 F and 2 F fractions indicated to be nutritionally superior to that of other fractions.

View full abstract

Antioxidative action of methionine in the systems containing linoleic acid (LA system), linoleic acid hydroperoxide (LAHPO system) and secondary degradation product of linoleic acid (LASP system) was studied and the following results were obtained.
1) Methionine inhibited the increase of POV in LA system and decreased the POV in LAHPO system, remarkably.
2) Amount of free methionine in LAHPO system was decreased during the reaction, and the decreases of POV and of methionine were highly corrected. Furthermore, it was confirmed that methionine in LAHPO system was transformed into methionine sulfoxide in the course of the reaction.
3) Methionine increased the acidity of the LAHPO system, while no significant difference was observed in hydroxyl group content in all the systems with or without methionine.
4) The presence of methionine in both LA and LAHPO systems did not increase the oxygen absorption of the systems.
5) From these results, the following mechanism on antioxidative action of methionine is proposed:

View full abstract

It has been demonstrated that cysteine has proxidative activity in the system containing linoleic acid (LA system). In order to clarify the mechanism of proxidative action of cysteine in the autoxidation of linoleic acid, the effects of cysteine in the systems containing linoleic acid hydroperoxide (LAHPO system) and secondary degradation product of linoleic acid (LASP system) as well as LA system were further studied. The following results were obtained.
1) The presence of cysteine in LA system increased POV, TBA value and oxygen absorption, especially at pH 4-5. The oxygen uptake of LA system with cysteine was immediately observed without any lag period after addition of cysteine.
2) No significant change in oxygen uptake was observed in LASP system with or without cysteine, whereas a slight increase of oxygen uptake was observed in LAHPO system containing cysteine. However, it was assumed that the slight increase of oxygen uptake in LAHPO system with cysteine might be effected by a small quantity of linoleic acid contaminated in this system.
3) Cysteine inhibited the decreases of POV in both LAHPO and LASP system.
4) It was confirmed by thin layer chromatography that cysteine in both LA and LAHPO system was transformed into cystine in the course of the reaction.
From these results, the following mechanism on proxidative action of cysteine is proposed: Cysteine takes plays an essential role in initiating the reaction which includes the oxygen uptake in autoxidation of linoleic acid and the acceleration of free radical formation, and then inhibits degradation of hydoperoxide by reacting with ROO. Consequently, cysteine is oxidized into cystine after the reactions.

View full abstract

The nutritive value of N-acetyl casein prepared by acetylating casein with acetic anhydride followed by 0.1N NaOH treatment was studied by the rat-growth method and the nitrogen-balance method on young rats.
1) The contents of acetyl and free ε-amino lysine of N-acetyl casein were determined (Table 1) and dinitraphenylated acetyl casein was analyzed for its amino-acid composition (Table 2). The resutts suggested that the lysine ε-amino groups in casein were almost completely blocked by acetyl groups.
2) N-Acetyl casein had a lower protein efficiency ratio than control casein (Tables 3, 4 and 5), but the decreased ratio of N-acetyl casein was completely alleviated by supplementation of lysine and threonine (Tables 4 and 5). N-Acetyl casein was also inferior to control casein in biological value, but the true digestibility of casein was not affected by acetylation (Table 6).
3) N-Acetyl casein made to react with caffeic acid-o-diphenoloxidase system showed a brown color and had a lower biological value than original acetyl casein (Table 6). The amino acid composition of the brown-colored acetyl casein, however, was similar to that of original acetyl casein (Table 7). Therefore, it was suggested that in addition to ε-amino group, other groups such as -CO·NH- were involved in the reaction of casein with caffeic acid-o-diphenoloxidase system.

View full abstract