α4-O-Benzoyl-pyridoxine (PN-4'MB) and α5-O-benzoyl-pyridoxine (PN-5'MB) were hydrolyzed in 10% aqueous solution of acetone at pH 1-4. They were hydrolyzed obeying apparent first-order kinetics. In the pH range of 1-7, PN-4'MB was hydrolyzed 10 times faster than PN-5'MB. At pH 7-12, an interconversion between the two derivatives was observed. They were bactericidal against Escherichia coli and Bacillus subtilis and prevented severe convulsions induced in mouse by 4'-methoxypyridoxine, a potent antagonist of vitamin B6. PN-4'MB was hydrolyzed with the homogenate of rat liver more easily than PN-5'MB. The metabolite of PN-MBs in man was identified as 4'-pyridoxic acid, i.e., a principal metabolite of PN, using high-performance liquid chromatography. The amount of urinary excretion of 4'-pyridoxic acid in 10 hr after oral administration of PN-4'MB or PN-5'MB was as large as that of PN.
Escherichia coli KG980, a vitamin B6 auxotroph derived from wild strain K12, concentrated exogenous pyridoxal in an energydependent manner, and the effects of energy sources and inhibitors on pyridoxal uptake, compared with those on proline uptake indicated that the energy required was in the form of phosphate bonds and not of membrane potential. The vitamin taken up was primarily present as pyridoxal 5'-phosphate and pyridoxamine 5'-phosphate intracellularly, and energy depletion decreased the accumulation as the phosphorylated derivatives but not as unaltered pyridoxal itself. This finding suggested that the intracellular phosphorylation, which was known to require ATP, was essential for the concentrative uptake of the vitamin. The suggestion was confirmed by the following evidence. 1) Pyridoxal oxime inhibited pyridoxal uptake by decreasing the intracellular phosphorylation without affecting the entry of pyridoxal across the cell membrane. 2) A pyridoxalkinase deficient mutant (MN 1) derived from the strain KG980 showed a low ability to take up pyridoxal because of the failure to accumulate it effectively as phosphorylated derivatives. The carrier-mediated nature of pyridoxal uptake, previously suggested by saturation kinetics, was further supported by the present finding that 4'-deoxypyridoxine inhibited pyridoxal uptake competitively, decreasing the intracellular appearance of unmetabolized pyridoxal. It is therefore most likely that pyridoxal enters the cells by facilitated diffusion and is accumulated by conversion to phosphorylated derivatives. Similar results on the uptake of pyridoxine and pyridoxamine are also presented.
The basal specific activities (S.A.; μmol of pyruvate/hr/ 108 erythrocytes) and the % deficiencies of activity of the glutamic oxaloacetic transaminase of the erythrocytes (EGOT) of 174 university students was 0.28±0.05 and 33±9%, respectively. There was a negative correlation, r=-0.65 (p<0.001), between the mean basal S. A. and the mean % def. (i.e., the lower the S.A., the higher the % def.). There were students with low basal S.A.'s who showed symptoms of carpal tunnel syndrome. On the basis of these data, 93% of 174 students had deficiencies of 20% and higher which was potentially correctable by oral pyridoxine; these students had B6-deficient diets. On the basis that a normal basal S. A. may be 0.7, and that the maximum S. A. (0.45) for all 174 students is about 65% of 0.7, all 174 students had varying vitamin B6 deficiency, and their diets provided inadequate amounts of this vitamin.
The plasma and red blood cell (RBC) levels of alphatocopherol in rats were determined in association with hemolysis induced by dialuric acid for a 7-week period of tocopherol deprivation following a 2-week period on tocopherol-containing diet. The patterns of decreases in plasma and RBC levels during the 7-week period were similar, differing in one respect. The RBC levels were characterized by a prompt decrease to non-detectable levels in the 4th week, while at that time a plasma level of 100μg/dl, albeit low, was maintained during the subsequent two weeks. Consequently, tocopherol ratios of RBC to plasma lowered throughout the experimental course. As for the relationship between these levels and hemolysis values, nonhemolysis was recorded in animals whose minimum RBC and plasma levels were 40μg/dl packed cell and 180μg/dl, respectively. This experiment showed that the plasma tocopherol level which has traditionally been accepted as the only index of hemolysis values does not always reflect them, and that in animals with hemolysis, only .RBC tocopherol levels were found to reflect hemolysis values.
In order to study the mechanism of intestinal cholesterol absorption, the relationship between the amount of cholesterol administered and the rate of absorption was investigated by the dual isotope plasma ratio method in vivo and the ligated-loop method in situ. The energy requirement of cholesterol absorption was also observed by means of the ligated-loop method. The results obtained are summarized below. 1) Tri-phase absorption was observed by the dual isotope plasma ratio method. When less than 300μg of cholesterol was administered, absorption increased linearly, with the coefficient of absorption being more than 80%. When the amount administered was between 300 and 500μg, the absorption was constant. With the administration of more than 500μg, absorption increased linearly, but the coefficient of absorption decreased to approximately 55%. 2) With the ligated-loop method, a second saturation profile was obtained when between 250 and 400μg of cholesterol was administered to a segment. When 50 to 250μg of cholesterol were administered, absorption increased in proportion to the increase in cholesterol dosage. 3) The mucosal uptake of cholesterol decreased to 40-60% of the control with the addition of metabolic inhibitors such as NaN3, KCN, 2, 4-DNP and ouabain, whereas the uptake of palmitate showed no significant decrease. In addition, the uptake of cholesterol decreased remarkably to 25% of the control with the lowering of body temperature from 37°C to 27 C. These results suggest the existence of an active transport system which has a limited capacity for cholesterol absorption and which requires energy for its operation in the physiological state.
This study was conducted to investigate the effects of various proportions of dietary carbohydrate and fat in diet on protein and carbohydrate metabolism. The growth rate, nitrogen balance, urinary and serum urea levels, and the activities of key ureogenic and gluconeogenic enzymes in the livers were examined in the weanling and growing rats. The rats were raised on a 20% casein diet containing various proportions of carbohydrate and fat, viz. 30% and 50%, 50% and 30%, 60% and 20% or 70% and 10% as calorie percent, respectively, for 10 days. For both weanling and growing rats, the growth rate was unaffected by the alteration in the proportions of carbohydrate and fat in the diets. However, in the rats fed on the 30% carbohydrate-50% fat diet, the urinary excrection of nitrogen and urea were reduced in both groups and these findings were reflected in the reduced serum urea level. Arginase activity decreased. In contrast, glucose-6-phosphatase activity was enhanced in the animals of the 30% carbohydrate-50% fat diet group as compared to the other groups. These results suggest that a low carbohydrate-high fat diet causes the reduction of urea formation and the enhancement of glucose formation at a fixed level of protein in the diets in weanling as well as in growing rats.
This paper describes the glycosylation sites of κ-casein component P-5 from bovine mature milk. A short glycopeptide was prepared from κ-casein component P-5 containing two carbohydrate chains by pronase P digestion, followed by gel filtration and ion exchange chromatographies. The glycopeptide obtained corresponded to residues 128-141 (Gly-Glu-Pro-Thr-Ser-Thr-Pro-Thr-Thr-Glu-Ala-Val-Glu-Ser) of κ-casein A from the results of analyses with chemical and enzymatic procedures. The effect of alkaline borohydride treatment indicated the presence of serine as well as threonine as the binding site of carbohydrate moieties. From the facts of Edman degradation and carboxypeptidase P hydrolysis of glycopeptide treated with alkali, the carbohydrate moieties were considered to be attached to threonine residue No. 133 and serine residue No. 141.
The antihypercholesterolemic activity of β-sitosterol and β-sitostanol was compared in male rabbits given a cholesterol-supplemented diet. β-Sitosterol and β-sitostanol were fed to these rabbits at the 0.5 level with cholesterol (0.5% acid 0.2% in experiments I and II, respectively). The serum cholesterol level tended to be lower in rabbits fed β-sitostanol than in the animals fed β-sitosterol even in experiment I. The β-sitostanol exhibited a significantly greater hypocholesterolemic activity in experiment II, LDL-cholesterol being decreased markedly. The liver cholesterol decreased in both groups of rabbits to a similar extent. β-Sitostanol prevented more effectively the formation of dietary cholesterol-induced atheroma in the abdominal aorta than β-sitosterol. It is most likely, together with the data reported previously on rats, that the hypocholesterolemic activity of β-sitostanol results from the significantly greater inhibitory effect on the intestinal absorption of cholesterol than that of β-sitosterol.
Nitrogen in the ethanol extract of the fruiting bodies of the common edible mushroom, Agaricus bisporus, accounted for about 60% of the total nitrogen of the fruiting bodies, and about 70% of the ethanolextractable nitrogen was attributable to the free amino acids and their derivatives. Identification and quantitative determination of the free amino acids and their derivatives contained in this fraction were performed after group separation. Of the 44 ninhydrin-positive compounds detected, alanine, glutamic acid, proline and arginine were the most predominant protein amino acids occurring in the free form, and ornithine, N-(γ-1-glutamyl)-4hydroxyaniline and γ-aminobutyric acid were the most plentiful nonprotein amino acids. An analytical method of the aromatic compounds characteristic of the mushroom is also described.