Varying Amounts Of Protein Research Articles

Aspects of the protein and the lipid composition of myelinoid marchi-positive bodies from mammalian spinal cord

The fraction floating on 0.32 M sucrose was isolated from normal mammalian spinal cord and analyzed with regard to protein and lipid composition. Comparisons were made with the myelin fraction isolated from the same spinal cord. A close relationship between the two fractions was indicated by a similar protein banding on SDS-polyacrylamide gel electrophoresis. The relative amounts of various proteins however were different and some high molecular weight proteins appeared unique to the floating fraction. The phospho- and galactolipid patterns, as revealed by thin-layer chromatography, were similar in the floating and the myelin fractions. The proportion of hydrophobic lipids, such as sterols and isoprenyl derivatives, was higher in the floating fraction. Bands co-migrating with cholesterol esters were detected only in the floating fraction from guinea pigs. Marchi-positive material of possible paranodal origin is enriched in the floating fraction. The present findings of a biochemical composition of the floating fraction closely resembling that of myelin is in line with the view that myelin turnover includes a step of degradation localized to the paranodal regions.

ウマ血清Ｔｒａｎｓｆｅｒｒｉｎの細管式等速電気泳動およびミクロ２次元電気泳動による観察

Capillary type isotachophoresis (CITP) and micro two-dimentional polyacrylamide gel electrophoresis (M2D-PAGE) were used by examining the genetic polymorphisms and the physiological variation of horse serum proteins. Both methods were useful for evaluating Tf typings. Especially, the CITP was a rapid analytical method. One of the very rare Tf type, Tf DM, which was undetectable by conventinal methods, was discovered by using this method. The amount of various proteins were estimated from the data on UV absorption. The Tf heterogenity was detectable by the M2D-PAGE. In addition, this method proved to be an excellent one for observing physiological conditions of each samples.

Some biological activities of Eikenella corrodens major outer membrane proteins.

Major outer membrane proteins of Eikenella corrodens, an organism frequently isolated from patients with periodontal disease, were tested for some biological activities. Mouse peritoneal macrophages, exposed at low concentrations of the above-mentioned proteins (between 0.05 and 5 micrograms/ml), showed evident and marked morphological modifications consisting of increases in the size and vacuolation of the cells. Higher concentrations showed a toxic effect. Low concentrations resulted in a selective release of lysosomal enzymes without any significant release of lactatedehydrogenase, and cytoplasmic marker; while concentrations of 25-50 micrograms/ml, which were toxic in trypan-blue exclusion test, increased LDH release. Eikenella corrodens major proteins increased the platelet aggregation of ADP and thrombin. The residual complement activity of serum samples incubated with various amounts of proteins at 37 degrees C for 30 minutes appeared strongly reduced with respect to controls, thus showing a consumption of the complement components. These results suggested that Eikenella corrodens major proteins may play a role in the development of periodontal lesions.

Hepatic gamma-glutamyltransferase activity: Its increase following chronic alcohol consumption and the role of carbohydrates

Prolonged feeding of diets containing ethanol leads to a significant increase of hepatic gamma-glutamyltransferase (GOT) activity which has been ascribed either to ethanol itself or to dietary imbalance with respect to carbohydrates. Hepatic GGT activity was therefore determined in Sprague-Dawley rats fed for five weeks liquid diets containing various amounts of protein, fat and vitamins. Compared to the normal control diet containing 47% of total calories as carbohydrates, a hypocaloric diet with 11% of total calories of the control diet as carbohydrates failed to result in major alterations of hepatic GOT activity (0.27 ± 0.04 Units/g liver wet weight vs 0.35 ± 0.06; N.S.). Similarly, hepatic GGT activity remained virtually unchanged under a hypercaloric carbohydrate rich diet. However, hepatic GGT activity was strikingly enhanced by a diet in which carbohydrates were replaced to the extent of 36% of total calories by ethanol to achieve a carbohydrate content of 11% (0.66 ± 0.12 Units/g liver; P < 0.005), indicating that alcohol itself is capable of increasing hepatic GGT activity. However, alcohol given with a high carbohydrate diet was shown to be incapable of increasing the hepatic activity of GGT. These data therefore indicate that upon chronic intake ethanol itself enhances hepatic GGT activity provided that the carbohydrate content of the diet is low, whereas such an effect could not be observed with ethanol in a high carbohydrate diet.

Effects of dietary levels of protein and fat on DDT (1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane) and liver lipid metabolism.

In order to examine the effect of dietary protein and fat on DDT metabolism and liver lipid concentration, rats were supplied with calory adjusted diets consisting of various amounts of protein and fat. The results suggested that dietary protein and fat changed the liver lipid concentration. They also showed that dietary protein and fat affected the residual concentration of DDT and its metabolites in the liver and adipose tissue. The change of the concentration of lipids in liver accompanied a change of the residual concentration of DDT in liver. This fact indicates that one effect of dietary protein and fat on the metabolism of DDT is attributable to the metabolic change of lipids in liver. Dietary protein accelerated the metabolism of DDT and reduced its residual concentration in liver. The results suggest that regression equations exist between the residual concentration of DDT in liver and (1) dietary factors and (2) lipid concentration in liver; In (DDT) = a x 1n (x1) + b x 1n(x2) + c x 1n(TL) + d (1) In(DDD or DDE) = a' x 1n(TL) + b' x 1n(PL) + c' (2) where x1, x2, TL, and PL are the dietary protein, dietary fat content, total lipid, and phospholipid concentration in liver, respectively. a, a', b, b', c, c', and d are constants. The concentrations of DDT and its metabolites estimated from equations (1) and (2) agrees well with the measured concentrations in liver.

The effect of Hofmeister anions and protein concentration on the activity and stability of some immobilized NAD‐dependent dehydrogenases

The effect of several factors on the activity and stability of alcohol dehydrogenase, glyceraldehyde-3-phosphate dehydrogenase, and 20beta-hydroxysteroid dehydrogenase, both free and immobilized on CNBr-activated Sepharose 4B, was investigated. Enzymes were im- mobilized under different conditions including various degrees of matrix activation, variable amounts of protein, in the presence, or in the absence of, additives (coenzymes, dithioth- reitol, salts). Activity recovery was in general satisfactorily high with 20beta-hydroxysteroid dehydrogenase, low with glyceraldehyde-3-phosphatedehydrogenase, and markedly linked to the concentration of immobilized protein with alcohol dehydrogenase. In the latter case the advantageous stabilizing effect of high enzyme concentrations was notably diminished by the parallel decrease of the effectiveness factor. The effect of high concentrations of anions of the Hofmeister series was examined. It was found that 1M phosphate and 0.5M sulfate dramatically stabilize both free and immobilized enzymes against inactivation by temperature and urea. K(m), values of apolar substrates were considerably lowered by the two anions while K(m) values of polar substrates were not affected. In some cases V(max) values also were influenced by high concentrations of these anions. The present results appear of interest particularly in view of enzyme utilization for analytical as well as for preparative purposes.

Dissolution of Hydroxyapatites Treated with Salivary Glycoproteins and Fluoride

Dissolution in an acidic buffer of synthetic hydroxyapatites covered with various amounts of proteins (0–482.5 μg/ml·m²) and treated with different quantities of fluoride (0–10 ppm of F^––) was studied. Analyses before and after protein coating were made on fluoridated samples. Both treatments individually or combined led to important decreases in apatite dissolution at pH 4 and 5. However, a small increase in dissolution was noted when fluoridation was performed before protein adsorption.

Effect of chemically defined diets on antral and serum gastrin levels in rats.

When rats were fed isocaloric amounts of chemically defined diets with variable amounts of protein (8-60%) or fat (0-30%) over a 10-day period, their serum and antral gastrin concentrations were, respectively, 60 and 40% lower than the levels of chow-fed rats. It was also determined that neither the low bulk content of these diets nor their inability to adequately buffer the gastric pH contributed to this response. The time course of this dietary-induced reduction in gastrin levels was investigated and it was found that the serum hormone levels were significantly reduced as early as 1-2 h after chow-fed rats were placed on these chemically defined diets. Antral gastrin levels were maintained at normal levels for 4-5 days after rats started consuming these synthetic diets and fell thereafter. With all of the chemically defined diets tested, the gastrin secretory response to a meal was significantly reduced. It therefore appears that synthetic diets lack some undefined food constituent present in chow that is required for the normal postprandial release of gastrin or, alternatively, that they contain an inhibitory factor which blocks the normal secretory response.

Drugs that enhance central serotoninergic transmission diminish elective carbohydrate consumption by rats

We previously showed (Science 198:1178, 1977) that fenfluramine or fluoxetine, drugs thought to enhance serotoninergic transmission, selectively decrease the rat's consumption of carbohydrates, without affecting protein intake, when animals are given simultaneous access to diets differing in protein (5% vs 45%) and carbohydrate contents; in contrast, d-amphetamine lacks this selective effect. Present studies affirm this relationship using another serotoninergic drug, MK-212, and show that the suppression of carbohydrate intake occurs whether the test diets contain variable amounts of protein, or carbohydrates, or of both nutrients. Evidence is presented that rats given diet mixtures containing various proportions of carbohydrates have the ability to regulate their carbohydrate intakes (i.e., to choose to eat amounts of each diet that, taken together, will give them a desired proportion of carbohydrate), and that this ability is independent of whether or not the carbohydrate consumed has a sweet taste. It is proposed that serotoninergic neurons comprise part of a behavioral feedback loop, whereby the consumption of carbohydrate (which, by altering plasma amino acid patterns, accelerates serotonin synthesis in brain neurons) diminishes the rat's subsequent tendency to consume additional carbohydrates. Drugs that enhance central serotoninergic transmission can probably be substituted for dietry carbohydrate to activate this behavioral loop.

On the trace of protein moiety in pulmonary surfactant

The role of proteins in pulmonary surfactant of rats was investigated using biochemical and biophysical methods. Pulmonary washing was fractionated on 1.5-m agarose columns, accompanied by disc electrophoresis. Fractions eluting with the void volume of the column and containing various amounts of proteins were spread onto an artificial dipalmitoyl lecithin/bovine serum albumin layer for measurement of surface pressure π-area curves. The results revealed a dependence of the surface pressure on the added protein. An assay system for [ 14C] phosphatidyl choline binding to proteins from solubilized alveolar material was developed to give evidence that the surface-active material is lipoprotein material. Surface activity and [ 14C]phosphatidyl choline binding to solubilized alveolar material can be lowered by trypsin incubation. A model for the molecular arrangement of the phospholipid-protein complex at the air-alveoli interface is proposed, partially based on data obtained by other laboratories. There is an indication that nonserum proteins are functionally an important component of the surface-active material isolated by lung lavage.

Effects of different bile salts upon the composition and morphology of a liver plasma membrane preparation. Deoxycholate is more membrane damaging than cholate and its conjugates

1. 1. Rat liver plasma membrane preparations were incubated with various bile salts at 0 or 37°C. The bile salts caused the removal of various amounts of proteins, membrane enzymes and phosholipids; the extent and nature of these losses, and the morphological changes which accompanied them, varied with the detergent used. 2. 2. Cholate, taurocholate and glycocholate removed appreciable amounts of protein from the saline-washed membranes, and considerable amounts of both phospholipids and the membrane enzymes, 5-nucleotidase, alkaline phosphatase, alkaline phosphodiesterase 1 and l-leucyl-β-naphtylamidase. These losses were greater at 37 than at 0°C. The material remaining contained membrane-like profiles, many of vesicular form, even when the preparation was almost completely devoid of phospholipids. 3. 3. Deoxycholate, both at 0 and 37°C, removed more protein, membrane enzymes and phospholipids than did cholate and its conjugates. The material remaining was mainly granular and unorganised and the only remaining features were structures resembling the nexus, and occasional desmosomes. 4. 4. Deoxycholate, a dihydroxy bile salt, therefore appears to cause greater perturbation of membrane structure than the trihydroxy bile salt, cholate, and its conjugates. The results may have implications for the effects of bile salts upon the membranes of liver cells during bile salt secretion and the production of bile.

Effects of different levels of dietary protein on brain glutamate dehydrogenase and decarboxylase in young albino rats.

Abstract— Studies were carried out to identify the minimum levels of protein (casein) needed in the diet in order to prevent or reverse the deficits in brain enzymes previously found with protein deficiency. Groups of weanling albino rats were fed diets containing variable amounts of protein (5, 8, 10, 15 or 20 per cent in experiment I, and 5, 6, 7, 8 or 20 per cent in experiment II) for 5 or 10 weeks. Deficits in brain wt and brain glutamate dehydrogenase and decarboxylase were found to be prevented by a diet containing 8 per cent or more of protein, although for optimum growth 15 per cent protein in the diet was found to be necessary. Groups of rats were fed a 5 or 20% protein diet for 10 weeks after which the 5% protein animals were either continued on the diet for another 10 weeks or changed to one containing 8, 10, 15 or 20% protein. The brain enzyme deficits found with the 5% protein diet were found to be fully reversed by feeding a 10% protein diet during rehabilitation.

Protein preference in protein-malnourished monkeys.

10 protein-malnourished monkeys and 8 dietary controls were run in a preference experiment designed to look at the differences in the way the 2 groups accepted foods containing various amounts of protein. Each monkey was given choices among diets containing 2%, 3.5%, or 25% protein, and non-food objects. The protein-malnourished monkeys showed a marked preference for the high-protein food; the adequately nourished monkeys chose all foods at the same ratio. The results indicated that a rapid learning process was involved in the formation of a preference for high-protein foods. The colors of the 2% and the 25% diets were then reversed, and the protein-malnourished monkeys showed a temporary disruption in their preference behavior, but they soon established a stable preference for the high-protein food. The experimental results are consistent with the hypothesis that protein-malnourished rhesus monkeys have a specific hunger for protein.

The influence of dietary protein on ascorbic acid metabolism in rats.

1. d-Glucuronolactone reductase, l-gulonolactone oxidase, uronolactonase, dehydroascorbatase, l-gulonate dehydrogenase and l-gulonate decarboxylase have been measured in the tissues of rats fed on diets containing variable amounts of protein. Rats fed on a protein-free or a 2% casein diet for 15 days showed a marked decline in the activities of d-glucuronolactone reductase, l-gulonolactone oxidase, uronolactonase and dehydroascorbatase in the liver, and no change in l-gulonate dehydrogenase and l-gulonate decarboxylase activities in the kidney when compared with rats fed on diets containing 9%, 18% or 25% casein. Giving diets containing 60% or 88% casein to rats did not appreciably alter the activities of uronolactonase, dehydroascorbatase, l-gulonate dehydrogenase and l-gulonate decarboxylase, but inhibited considerably the activities of d-glucuronolactone reductase and l-gulonolactone oxidase in the liver, resulting in decreased synthesis of ascorbic acid. 2. Rats fed on a 25% casein diet showed maximal weight gain, higher tissue reserve of ascorbic acid and higher urinary excretion of both ascorbic acid and glucuronic acid when compared with rats fed on diets containing lower or higher amounts of protein.

Interaction of Food Colors with Protein (V)

The spectra of a number of isoxanthen dyes undergo pronounced alternation in the presence of small amounts of various proteins, particularly at pH 5.2 and 7.0. For example, free Rose Bengale has an absorption maximum at about 545mμ. When the dye is bound by bovine plasma albumin, it is altered to 562mμ absorption band at about pH 5.2, and when by casein, it is changed to 551mμ. The spectral shifts are due to the complexformation between dye and protein. It should be emphasized that these isoxanthen dyes are bound by bovine plasma albumin, egg albumin, casein and phaseolin, as are apparent from the shift of optical absorption. The isoxanthen dyes employed in the present experiment contain Rose Bengale, Phloxine, Eosine and Erythrosine. Such optical behaviors will be in accord with the evidence by dialysis-equilibrium method.

Serine Biosynthesis in Rat Liver: REGULATION OF ENZYME CONCENTRATION BY DIETARY FACTORS

Abstract 3-Phosphoglycerate dehydrogenase, phosphoserine phosphatase, d-glycerate dehydrogenase, and serine dehydratase have been measured in rats fet diets containing variable amounts of protein. Rats fed 2% casein diets for 7 days had a marked increase in 3-P-glycerate dehydrogenase and P-serine phosphatase and a simultaneous decline in serine dehydratase when compared to rats fed chow or a 25% casein diet. The increased enzyme levels were prevented by the addition of 1% cysteine to the 2% casein diet but this did not alter the decline in serine dehydratase. On 88% casein diets a depression of 3-P-glycerate dehydrogenase and P-serine phosphatase resulted, while prompt increase in serine dehydratase occurred. No reproducible changes in d-glycerate dehydrogenase occurred on any of the diets studied. The administration of actinomycin D on several schedules consistently caused an inhibition of the changes noted with the 2% casein diet. These observations plus studies with cycloheximide suggest that the observed alterations in enzyme concentrations may be mediated by altered rates of enzyme synthesis. Studies of potential feedback inhibitors of the reactions measured were negative for 3-P-glycerate dehydrogenase and d-glycerate dehydrogenase. Inhibition of P-serine phosphatase by l-serine may have physiological significance in mammals. The inhibition of serine dehydratase by l-cysteine is described.

Chromosome complements of Rana pipiens embryos developing from eggs injected with protein from adult liver cells

Fertilized eggs of Rana pipiens were injected with various amounts of protein extracted from adult liver cells of the same species. Such injected embryos generally exhibited developmental arrest at the late blastula stage. Previous work showed that nuclei of such embryos had been irreversibly changed so that they could promote development only to the beginning of gastrulation when transplanted to enucleated eggs. In the present study chromosome analyses were made at successive stages in the development of injected embryos. These analyses revealed the presence of chromosomal abnormalities such as rings, fragments, and loss of chromosomes in a large proportion of cells in stages prior to arrest. These chromosomal abnormalities may reasonably be invoked as a sufficient cause for the arrest of development.

Blood lipids and human atherosclerosis.

The transport of cholesterol and other lipids of serum is almost wholly in the form of very large molecular complexes of these lipids with variable amounts of protein. The exact components present in the blood of a particular individual may be quantitatively described both as to character and concentration by ultracentrifugal flotation of these components in the analytic ultracentrifuge. With this technic it is possible to demonstrate the presence of certain lipid and lipoprotein components which are related to coronary atherosclerosis, to hypertension and to other diseases associated with atherosclerosis, such as diabetes mellitus, the nephrotic syndrome and hypothyroidism. The blood level of these components may be influenced by dietary means. The blood level of these components is poorly correlated with the analytic serum cholestrol determined by the Schoenheimer-Sperry method.