Serum Free Amino Acids Research Articles

Absolute rate constants for the reaction of hypochlorous acid with protein side chains and peptide bonds.

Hypochlorous acid (HOCl) is a potent oxidant, which is produced in vivo by activated phagocytes. This compound is an important antibacterial agent, but excessive or misplaced production has been implicated in a number of human diseases, including atherosclerosis, arthritis, and some cancers. Proteins are major targets for this oxidant, and such reaction results in side-chain modification, backbone fragmentation, and cross-linking. Despite a wealth of qualitative data for such reactions, little absolute kinetic data is available to rationalize the in vitro and in vivo data. In this study, absolute second-order rate constants for the reactions of HOCl with protein side chains, model compounds, and backbone amide (peptide) bonds have been determined at physiological pH values. The reactivity of HOCl with potential reactive sites in proteins is summarized by the series: Met (3.8 x 10(7) M(-1) x s(-1)) > Cys (3.0 x 10(7) M(-1) x s(-1)) >> cystine (1.6 x 10(5) M(-1) x s(-1)) approximately His (1.0 x 10(5) M(-1) x s(-1)) approximately alpha-amino (1.0 x 10(5) M(-1) x s(-1)) > Trp (1.1 x 10(4) M(-1) x s(-1)) > Lys (5.0 x 10(3) M(-1) x s(-1)) >> Tyr (44 M(-1) x s(-1)) approximately Arg (26 M(-1) x s(-1)) > backbone amides (10-10(-3) M(-1) x s(-1)) > Gln(0.03 M(-1) x s(-1)) approximately Asn (0.03 M(-1) x s(-1)). The rate constants for reaction of HOCl with backbone amides (peptide bonds) vary by 4 orders of magnitude with uncharged peptide bonds reacting more readily with HOCl than those in a charged environment. These kinetic parameters have been used in computer modeling of the reactions of HOCl with human serum albumin, apolipoprotein-A1 and free amino acids in plasma at different molar excesses. These models are useful tools for predicting, and reconciling, experimental data obtained in HOCl-induced oxidations and allow estimations to be made as to the flux of HOCl to which proteins are exposed in vivo.

ランドレース純粋種およびその交雑種の血清中脂質成分濃度および遊離アミノ酸濃度の差異

ランドレース純粋種およびその交雑種の血清中脂質成分濃度および遊離アミノ酸濃度の差異

Effects of taste stimulation on the behavior of serum amino acid concentrations and amylase and trypsin activities in fasting rats.

The effect of taste stimulation on serum free-amino acid concentrations and amylase and trypsin activities in fasting rats was studied. Following an acclimation period of 5 d, male Sprague-Dawley rats were fasted for 4 d and sacrificed after taste stimulation with a palatable sodium saccharin or unpalatable quinine sulfate flavored diet. Blood was collected from the portal vein and inferior vena cava at 0, 5, 10, 20 and 30 min after taste stimulation. Intestinal contents were also collected at the same time intervals as the blood collections. Total amino acid concentrations in the saccharin stimulated group increased significantly at 5 and 20 min following taste stimulation in comparison with the control of 0 time in the portal vein, and a significant difference between the saccharin and quinine stimulated groups was also observed at 5 min. No difference was found in the inferior vena cava. A high level of alanine and low level of glutamine were depicted in the portal vein as compared to that of the inferior vena cava. The elevation of alanine that is gluconeogenic amino acid was remarkable in the saccharin group at 20 min in the portal vein. Moreover, amylase and trypsin activities in the saccharin group reached peak values promptly and kept constant throughout the experiment as compared to the quinine group. The results suggest that taste stimulation originates changes in the cephalic phase amino acid concentrations in the portal vein and that taste information, overcoming a hunger, plays an important role in amino acid metabolism and digestive enzyme activities. Therefore, eating with gusto is significant for the maintenance of body functions even under starvation conditions.

Nutritional evaluation and metabolic effects in rats of protein isolates obtained from seeds of three legume species

Three legume seeds, peas (Pisum sativum L), faba bean (Vicia faba L) and soybean (Glycine max L) and their respective protein isolates, were assayed for their nutritional value and metabolic effects. Feeding rats with either the legume seeds or the protein isolates resulted in an impairment in growth and significantly lower nutritional indices as compared to the control group. Protein apparent digestibility improved in the protein isolate fed rats, with similar digestibility data to those observed in the casein fed group. Liver, gastrocnemius muscle and spleen weights were decreased by legume consumption, and the enlargement detected in the small intestine weight in the animals fed on the legume seeds, was partially reversed in the animals receiving the protein isolate. This reversal was significant in rats offered faba bean protein isolate. Biochemical parameters were consistent in the legume groups, and hypoglycaemic and hypotriacylglycaemic responses were observed for the legume meals. Lower uric acid levels were found in some of the legume fed animals. Serum free amino acid profiles were affected by the legume intake, as compared with casein. Methionine and taurine concentrations decreased, whereas serine concentrations were augmented. Other amino acids, particularly glycine and valine, also showed modified plasma concentrations. These results suggest that the preparation of protein isolates, following an easy protocol, yield products with better digestibility, which keep the positive effects on glucose and triacylglyceride plasma levels, and partially reduce some other undesirable consequences related to legume consumption. © 1998 Society of Chemical Industry

Profiles of serum proteins and free amino acids associated with chloroquine retinopathy.

The effects of chronic chloroquine administration on serum proteins and free amino acids of rabbits and the accompanying ultrastructural changes in the retina were investigated. Thirty pigmented rabbits were injected intramuscularly with chloroquine diphosphate (14 mg/Kg bw). Fifteen rabbits served as control. Blood samples drawn after 1, 2, 3, 4, 5, 6 and 12 months were assayed for serum proteins by Bio-analytic kits and horizontal electrophoretic technique. Free amino acids were determined by Beckman analyzer. Central retinal tissue was fixed in 4% glutaraldehyde, embedded in araldite CY212 and sectioned for ultrastructural examination. Histopathologic changes were apparent within three months, initially affecting the pigment epithelium and photoreceptors and later involving the remaining neuroretinal layers. Hypoproteinemia gradually developed mainly due to a sharp drop in albumin and alpha 1 and 2 globulin fractions, inspite of an increase in beta and gamma globulin fractions. The concentration of non-essential amino acids varied considerably from a depletion of taurine, aspartine, glutamine, tryptophan and arginine to an increase of serine, alanine, GABA and ornithine. The most outstanding effect was the disappearance of tyrosine and its return to normal value at the end of the experiment. The disturbances in protein pattern and free amino acid levels are an indication of chloroquine toxicity and may be implicated in the retinopathy.

Metabolic response to feeding rates in common carp, Cyprinus carpio

Common carp weighing about 46 g were fed on a commercial diet for 30 days at various daily feeding rates of 2.28 (satiation), 2.07, 1.85, 1.64, 1.16, 0.72 and 0% (starvation), and the hepatopancreatic enzyme activities and body composition were determined. The concentrations of serum triglyceride and cholesterol as well as body fat and glycogen contents decreased as the feeding rate decreased, while serum glucose and free amino acid concentrations scarcely changed. The serum free fatty acid concentration in the starved fish was higher than those in the fed fish. The activities of hepatopancreatic glucosephosphate isomerase, pyruvate kinase, glucose-6-phosphate dehydrogenase, phosphogluconate dehydrogenase, NADP-isocitrate dehydrogenase, and -malate dehydrogenase significantly decreased with decreasing feeding rates, and there were strong positive correlations between enzyme activities and feeding rates. On the other hand, glucose-6-phosphatase and alanine aminotransferase activities remained relatively constant. These results suggest that feed restriction stimulated fatty acid and glycogen mobilization, maintained gluconeogenesis and amino acid degradation, and depressed glycolysis and lipogenesis in the hepatopancreas.

Studies on fatigue of night duty workers at a newspaper office.

Fatigue of night duty workers in different divisions of a newspaper office was investigated by physiological methods such as the Blinker, Flicker and grip methods. The relationship between fatigue and hematological parameters such as hemoglobin (Hb), the hematocrit (Ht), serum-free amino acid levels, and indices of liver function such as the GOT and GPT levels were also examined. The composing and press room workers mainly complained of the subjective symptom of muscle fatigue, while workers in the photo-engraving and editorial departments mainly complained of mental fatigue. The overall rate of fatigue in the newspaper office was about 38.1%, but varied from one division to another, being especially high in the photo-engraving and editorial departments. The subjects with fatigue had low levels of serum GOT and GPT and high levels of serum-gluconeogenic amino acids, such as aspartic acid, glutamic acid, prolin, glycine, and alanine. These altered levels of serum-free amino acids and GOT and GPT seemed to be due to increased secretion of adrenal corticoid hormone caused by the stress of fatigue.

Effects of spinach leaf protein concentrate on the serum cholesterol and amino acid concentrations in rats fed a cholesterol-free diet.

The effects of spinach leaf protein concentrate (SPPC) on serum and liver lipid concentrations and on serum free amino acid concentrations were examined in rats fed a cholesterol-free diet containing 2 and 10% fats. The serum total cholesterol, triacylglycerol and phospholipid concentrations in the rats fed an SPPC diet containing 2% corn oil were significantly lower than those of the rats fed a corresponding casein diet. When 10% corn oil or lard was used, the serum cholesterol-lowering effect of the SPPC became insignificant, but the serum and liver triacylglycerol concentrations were kept at significantly lower levels. Both the amounts of fecal neutral steroids and bile acids were significantly higher in the rats fed the SPPC than those of the casein-fed rats. The concentrations of serum threonine, serine, glutamine, glycine, cystine, and isoleucine were significantly higher in the rats fed the SPPC diet containing 2% corn oil compared with those of the control rats, but when the dietary fat was raised to 10%, only glycine showed a higher serum concentration. These results indicate that the SPPC has a stronger cholesterol-lowering effect at a lower dietary fat level, 2%, and the activity is partly due to the inhibition of intestinal absorption of cholesterol and bile acid, and partly due to an increase in the concentration of some of the serum amino acids.

養魚飼料のタンパク質源 ＸＩＩ ブリ幼魚における加熱および無加熱大豆油粕の消化と血清成分の経時変化

In order to clarify differences in the digestion and absorption process of raw and heated defatted soybean meals (SBM) in juvenile yellowtail Seriola quinqueradiata, the fish were force-fed with the two kinds of SBMs as well as raw fish and fish meal as control, and post-feeding changes in digesta quality, serum constituent concentrations, and protein digestibility were determined. The intestinal digesta contents were higher in the fish fed with either SBM than those in the fish fed with raw fish during the experimental period. The digesta in the raw SBM-fed group passed rapidly through the stomach and intestine at a similar speed as in the raw fish-fed group, but the solubility and digestibility of the intestinal digesta protein and serum free amino acid concentration were lowest among the four protein sources, probably due to the activity of trypsin inhibitor in raw SBM. On the other hand, the digesta in the heated SBM-fed group passed slowly through the digestive tracts, and the solubility of the intestinal digesta protein was higher than that in the raw SBM group, while being similar to that in the fish meal-fed group. These results indicate that the digestion and absorption process of raw SBM was disturbed by its trypsin inhibitor, but was improved by heating to a similar degree to fish meal under the experimental conditions.

Profiles of Serum Amino Acids to Assess Condition of Cotton Rats (Sigmodon hispidus)

We investigated the use of concentrations of blood-serum amino acids to assess status of dietary proteins of juvenile cotton rats ( Sigmodon hispidus ). Eighteen juvenile animals were randomly assigned to isocaloric diets containing 4 or 16% crude protein, and serum concentrations of amino acids were determined by high-pressure liquid chromatography on days 30 and 45 of a 45-day feeding trial. Concentrations of methionine, threonine, tryptophan, valine, hydroxyproline, and branch-chain amino acids (BCAA) were depressed, whereas histidine and proline were elevated among low-protein-fed cotton rats. The glycine/(leucine + valine) and phenylalanine/tyrosine ratios were greater in serum of cotton rats fed low-protein diet, whereas the tyrosine/neutral amino acids (NAA) and tryptophan/NAA ratios were depressed. Concentration of several free amino acids in serum of juvenile cotton rats differed between 30- and 45-day samples. Because diet × sample interactions were significant for only tryptophan and hydroxyproline, temporal changes probably were a reflection of age-related alterations in developmental physiology and not effects of diet. Our results indicate that clinical profiles of selected amino acids in serum can provide a useful technique for assessing protein nutritional status and quality of diet in small mammals.

Effect of prolonged anticonvulsant medication in epileptic patients: Cognitive function, serum free amino acids, vitamin B12 and folic acid

Effect of prolonged anticonvulsant medication in epileptic patients: Cognitive function, serum free amino acids, vitamin B12 and folic acid

Dietary Casein and Soybean Protein Affect the Concentrations of Serum Cholesterol, Triglyceride and Free Amino Acids in Rats

This work was undertaken to investigate the concentrations of free amino acids in blood after food was withheld from growing, male Wistar rats fed cholesterol-free, low fat (1 g corn oil/100 g) diets with casein or soybean protein for 2 wk. A diet containing 22.5 or 23.5 g/100 g of soybean protein was hypocholesterolemic compared with a diet containing 20.0 g casein/100 g diet. A comparison of serum amino acids in soybean protein-fed vs. casein-fed rats showed that, whereas concentrations of many amino acids were lower in the soybean protein-fed rats compared with the casein-fed groups, glycine was the only amino acid having a higher concentration. Further, alanine was significantly lower in the soybean protein-fed rats compared with the casein-fed rats, and the protein-induced differences in glycine and alanine concentrations of unfed rats were reproducible. When diets containing 15.0% casein or 30.0% soybean protein, a casein diet supplemented with glycine and a soybean protein diet supplemented with methionine were compared, the changes in serum glycine and alanine correlated with the changes in serum cholesterol. Concentrations of several amino acids, particularly valine, leucine and tyrosine, also changed when serum cholesterol concentrations varied, but these effects could not be explained by our experiments. The results suggest that a change in serum concentration of glycine and alanine of unfed rats may be related to the change in serum cholesterol concentration.

Influence of dietary soybean trypsin inhibitors and DL-ethionine on sulfur amino acid adequacy of diets for young rats.

Weanling male Wistar rats were fed 20% protein diets based on casein or either of two combinations of soy protein isolate and ground raw soy providing three levels of soybean trypsin inhibitors (SBTI; 0, 448 and 808 mg of trypsin inhibited per 100 g of diet respectively). DL-ethionine was included at three levels (0, 0.05% and 0.10%) with each level of SBTI. After 4, 8 and 12 weeks of ad libitum feeding, diets containing SBTI without DL-ethionine were associated with decreases in weight gain, feed efficiency, serum cholesterol and serum urea nitrogen. Higher levels of triglycerides, glutamate pyruvate transaminase (SGPT) and altered serum free amino acid levels were also found. Increased dietary levels of DL-ethionine also resulted in deficits in growth and feed efficiency, decreased serum cholesterol, increased SGPT and similar alterations in serum free amino acids. Combination of dietary SBTI with DL-ethionine resulted in even greater growth deficits and serum cholesterol decreases as well as increases in SGPT and serum triglycerides and changes in serum free amino acid levels. Methionine deficiency in the young rats fed SBTI and DL-ethionine was indicated by the changes in serum amino acids and growth deficits. Moderation of some effects over the 12 week test period suggested decreased methionine requirements in the older rats.

Li Chang-lian et al. An analysis of serum free amino acid profiles in severely burned patients. (Chinese) Chin. J. Plast. Surg. Burns 6

Li Chang-lian et al. An analysis of serum free amino acid profiles in severely burned patients. (Chinese) Chin. J. Plast. Surg. Burns 6

Aminino acid profiles in dogs with chronic renal failure fed two diets

Summary Amino acid profiles and serum albumin and serum total protein concentrations were evaluated in dogs with renal disease. Nine dogs ranging in age from 1 to 15 years were identified as having mild to moderate chronic renal failure (crf; exogenous creatinine clearance, 0.5 to 2.13 ml/kg of body weight/min). These dogs and a group of 10 clinically normal control dogs, were fed a diet containing 31% protein for 8 weeks, at which time serum and urine imino acid assays and clearance studies were performed. All dogs then were fed a diet containing 16% protein for 3 weeks and then reevaluated. Chronic renal failure was associated with mild abnormalities in serum concentrations of amino acids. When fed the higher protein diet, dogs with crf had lower serum concentrations of glutamine, leucine, proline, and serine and higher serum concentrations of cystathionine and 3-methylhistidine than clinically normal control dogs. When fed the low protein diet, dogs with crf had lower serum serine concentrations and higher serum concentrations of cystathionine, phenylalanine, and 3-methylhistidine. Urine excretion of amino acids in all dogs on both diets was low, and dogs with crf had lower renal clearances of 3-methylhistidine than control dogs. There were no significant differences in concentrations of serum albumin and total solids between either group, regardless of diet. We concluded that dogs with mild to moderately severe crf have mild abnormalities of serum free amino acid concentrations, but renal conservation of essential amino acids is not impaired.

Effects of soybean trypsin inhibitors and dl-ethionine on growth and serum parameters in young rats

Two three week feeding trials tested the effects of dietary soybean trypsin inhibitors (SBTI) and/or DL-ethionine (methionine antagonist) on growth, protein digestibility, and clinical parameters in young male and female Sprague Dawley and Wistar rats. SBTI-fed rats had decreased weight gain, feed efficiency, protein digestibility and increased serum urea nitrogen relative to casein-fed control animals. Ethionine without SBTI also had negative effects. Combination of the two factors resulted in greatest growth deficits and increased serum levels of urea nitrogen, triglycerides, alkaline phosphatase and glutamate pyruvate transaminase. Dietary inadequacy or unavailability of sulfur amino acids in rats fed SBTI and ethionine was suggested by poor growth and serum accumulation of total essential amino acids, methionine sulfoxide, and several amino acid precursors of the methionine transsulfuration pathway. DL-methionine supplementation of diets containing SBTI or SBTI + ethionine or use of a soy protein isolate + ethionine diet (low in SBTI) improved growth and feed efficiency and normalized clinical chemistry parameters and serum free amino acid levels further suggesting that a deficit in supply or availability of sulfur amino acids was a factor in the observed changes.

Rapid Analysis of Nutritionally Important Free Amino Acids in Serum and Organs (Liver, Brain, and Heart) by Liquid Chromatography of Precolumn Phenylisothiocyanate Derivatives

An amino acid analysis method for protein hydrolysates, using precolumn phenylisothiocyanate (PITC) derivatization and liquid chromatography, was modified for its application in rapid analysis of commonly occurring free amino acids in serum and other physiological samples. The modifications included changes in column temperature (47.5 degrees C compared to 25-35 degrees C used in analyzing protein hydrolysates), method of preparing standard and test samples, and gradient conditions. By using a Waters Pico-Tag amino acid analysis 15 cm long column (which is also used for analyzing protein hydrolysates), separation of 27 PTC-amino acids in human serum and rat liver, brain, or heart was completed in 20 min by the modified method. The total time for analysis and equilibration was 30 min. The modified method was much faster than the traditional ion-exchange methods (2-3 h) or the existing liquid chromatographic methods using PITC derivatization (66-80 min) for determining nutritionally important free amino acids in physiological fluids and tissues. Variability of the method (expressed as coefficients of variation) for the determination (including deproteinization, derivatization, and liquid chromatography) of all amino acids was less than 5%, which compared favorably with the reproducibility of ion-exchange methods.

Effect of exogenous cortisone on amino acid metabolism in rats

1. 1. The effect of exogenous cortisone on concentration of free amino acids in serum, skeletal muscle, kidney, small intestine and liver was studied. 2. 2. The amino acid pool in serum, skeletal muscle and small intestine decreased significantly. 3. 3. Glutamine synthesis increased significantly in skeletal muscle. 4. 4. Levels of branched amino acids increased in serum and small intestine. 5. 5. Levels of alanine increased in kidney and liver.

Metabolic adaptation to prolonged starvation of carp.

In order to clarify the biochemical aspects of metabloic adaptation to prolonged starvation in fish, carp Cyprinus carpio were starved for 30 days in a 800l fiber reinforced plastic aquarium, and changes in hepatopancreatic enzyme activities and body composition were determined. The protein content of the serum, hepatopancreas, muscle and whole body decreased gradually over the 30 day-period of starvation, whereas, the hepatopancreas glycogen content and serum triglyceride concentration decreased rapidly during first 7 days and remained low thereafter. However, the concentration of serum glucose remained almost constant throughout the starving period, and the concentrations of serum free amino acid and free fatty acid increased gradually. The activities of hepatopancreatic glucosephosphate isomerase, glucose-6-phosphate dehydrogenase, phosphogluco-nate dehydrogenase, NAD-and NADP-malate dehydrogenases, and NAD-isocitrate dehydrogenase were significantly decreased during starvation, whereas, activities of glucose-6-phosphatase, glutamic pyruvic transaminase and glutamic oxaloacetic transaminase were similar to or higher than those in prestarvation. These data indicate that, during starvation, glycoloysis, lipogenesis and energy production markedly decrease, while gluconeogenesis and amino acid degradation remain and continue to supply glucose in the hepatopancreas. Also, during prolonged starvation, the body protein and lipid are consumed as energy sources after an exhaustion of glycogen.

Whole Rat Embryos Require Methionine for Neural Tube Closure when Cultured on Cow Serum

Headfold-stage rat embryos, when cultured on cow serum without supplemental methionine, failed to close their neural tubes, lacked eyes and branchial arches, were abnormally shaped and were reduced in protein content compared to methionine-supplemented embryos. Methionine was essential during the first 18 h of culture, a period in which neural tube closure was initiated in supplemented cultures. All cow serum samples tested were found to require methionine addition, and the methionine was not replaced by other amino acids or vitamins, including folate. Methionine was not toxic to cultured rat embryos at concentrations up to at least 500 micrograms/ml. Analyses of serum free amino acids revealed lower levels of free methionine in cow serum compared to rat serum, and cow serum proteins contained less methionine relative to other amino acids than did rat serum proteins. Dialysis of cow serum reduced but did not eliminate the requirement for methionine. This suggested either that the free amino acids of cow serum were imbalanced or that a dialyzable component in serum interfered with the availability/utilization of methionine. Dietary supplementation of cows with rumen-protected DL-methionine increased the serum methionine level, and serum drawn from supplemented cows supported normal rat embryo development without additional methionine.