Α-amino Nitrogen Content Research Articles

The response of plasma insulin, glucose and non-esterified fatty acids to various hormones, nutrients and drugs in the domestic fowl.

SUMMARY The relationships between plasma insulin, glucose, non-esterified fatty acid (NEFA) and α-amino nitrogen concentrations in the domestic fowl have been studied. During a 72-hr. fast the plasma glucose concentration fell while the NEFA concentration rose but there was no change in plasma insulin concentration. Both oral and intracardiac glucose increased the plasma insulin concentration and lowered the plasma NEFA and α-amino nitrogen concentrations. Oral amino acids increased plasma insulin and glucose concentrations but had no effect on plasma NEFA. Intracardiac ox insulin depressed plasma glucose and α-amino nitrogen and increased the plasma NEFA concentration. Intracardiac glucagon increased both plasma glucose and NEFA and depressed the plasma α-amino nitrogen concentrations but had no significant effect on plasma insulin. Intracardiac adrenaline had no effect on plasma NEFA but increased plasma glucose concentration and caused a small depression in plasma insulin concentration.

Coprecipitation of amino acids with tungstic acid precipitation of plasma proteins

The effect of tungstic acid precipitation of plasma proteins on the nonprotein α-amino nitrogen concentration and on the recovery of added 14C-labeled amino acids was investigated. Total loss of α-amino nitrogen from the rabbit plasma was estimated to be between 10 and 23%. The major loss of α-amino nitrogen appears to be due to the loss of diamino acids; the loss of 14C-labeled arginine, histidine, and lysine ranged between 30 and 50%. Loss of neutral amino acids was for the most part very small (less than 2%) and, with the exception of threonine, not significant. Loss of glutamic acid was estimated to be 4%. The actual extent of amino acid loss was shown to depend on the relative concentration of proteins and precipitating agents and was not greatly influenced by reasonable variations in precipitating procedures. The lost amino acids are firmly bound to the precipitate and cannot be recovered even with several washes. It was concluded that most of the observed loss of α-amino nitrogen is due to binding of dibasic amino acids to a protein-tungstate complex.

Insulin Stimulation of Amino Acid Uptake in Rat Diaphragm: RELATIONSHIP TO PROTEIN SYNTHESIS

Abstract 1. Puromycin dihydrochloride inhibited uptake of α-aminoisobutyric acid (AIB), 1-aminocyclopentane-1-carboxylic acid, and α,γ-diaminobutyric acid by intact diaphragm muscle from male rats weighing 60 to 90 g when the antibiotic was added to the system in vitro 120 and 180 min before the addition of the substrate. 2. In the absence of insulin, this inhibitory response was also produced by cycloheximide, but not by the aminonucleoside of puromycin or actinomycin D. In the presence of insulin, AIB uptake was inhibited by actinomycin D and the aminonucleoside of puromycin as well as by puromycin dihydrochloride and cycloheximide, the degree of inhibition paralleling inhibition of l-lysine incorporation into protein. 3. The antibiotics shown to inhibit amino acid transport did not change tissue water spaces, oxygen consumption, the concentration of α-amino nitrogen in the incubation medium, or the diffusion constant for AIB (Kd). 4. In diaphragm muscle from rats weighing 60 to 90 g, incubation with puromycin for 180 min reduced subsequent stimulation of AIB transport by insulin. In muscle from animals weighing 220 to 250 g, stimulation by insulin was completely abolished by puromycin. 5. These studies show that puromycin inhibits the synthesis of a rapidly turning over protein or proteins involved in the transport of AIB. The results suggest that insulin stimulates amino acid transport in two distinct ways: by increasing the affinity of the carrier mechanism for amino acids; and by initiating the synthesis of a specific protein or proteins which enhances transport.

Free Amino Acids, Ammonia and Urea Concentrations in the Blood Plasma of Starved Lambs

The effect of short periods of starvation on the free amino acid, ammonia and urea concentrations in blood plasma of Dorset Horn × Border Leicester-Merino lambs was studied in 3 age groups between 14 and 20 weeks of age. They were subjected to one of the following treatments: 1) fed a maintenance ration for 3 weeks; 2) fed a maintenance ration for 2 weeks and starved for 1 week; or 3) totally starved for 3 weeks. The concentration of free amino acids, ammonia and urea were determined in the blood plasma at the time of killing. Starvation for 3 weeks resulted in a significantly lower concentration of total α-amino nitrogen in the plasma when compared with the control fed lambs. The individual amino acids which were significantly lower were threonine, glutamic acid, alanine, valine, isoleucine and leucine and also urea. The concentration of lysine in the blood plasma was significantly higher in the starved lambs.

The relationship between amino nitrogen and protein concentrations in rabbit blastocyst fluid

The queston of how the oligolecithal mammalian embryo is supplied with the material necessary for the synthesis of proteins, especially before nidation, is still open to investigation. The authors have studied the rabbit blastocyst fluid between the seventh and ninth days after mating and determined the α-amino nitrogen in this fluid. On the seventh day after mating, a high level of α-amino nitrogen was found in the blastocyst fluid, exceeding by five times the level in the maternal blood. The concentration of protein was only one tenth of the level in blood serum. During the period of implantation, a progressive decrease in α-amino nitrogen concentration and an increase in protein concentration takes place.

Free amino acids of human foetal and adult liver.

THE glycine and α-amino nitrogen concentrations in rabbit foetal muscle are approximately three times as great as in maternal muscle1. Previous studies on regenerating rat liver indicate increased concentrations of α-amino nitrogen and glutathione during regeneration2. These observations suggest a relationship between high concentrations of amino acids and increased protein synthesis. Studies of the amino acid concentrations of tumours also show that elevated concentrations of amino acids are present during rapid growth3. The foetal liver of the guinea-pig, however, unlike foetal muscle, has been found to have the same concentration of amino acids as the maternal liver.

Tryptic hydrolysis of paramyosin from invertebrates: Rate and extent of proteolysis

The rate extent of the action of trypsin (EC 3.4.4.4) on Pinna nobilis and Pecten maximum paramyosin were followed by different methods, namely total nitrogen, α-amino nitrogen and arginine content in the trichloroacetic acid-soluble fraction, alkali uptake and N-terminal residues in the digest mixture. The results obtained permi one to say that the number of bonds split typrsin in both cases is approximately half of the susceptible bonds present in the whole molecule. About 80% of the total arginine liberated by the enzyme is free or in an N-terminal position. The kinetics of proteolysis were studied by two different methods and they clearly indicate the existence of at least two and possibly three simulataneous reactions proceedings at different rates. The rate contants suggest that one class of peptide bonds is much more susceptible to attack than others. The results are discussed in the light of the proposed secondary and tertiary structure of paramyosin.

The Amino Acid Metabolism of Microsporum canis

SUMMARY: Microsporum canis utilized several single amino acids as nitrogen source during growth on a defined medium; ammonia was also used but not nitrate or methionine. Several extractants for releasing cytoplasmic contents were examined. With acetic acid (100 g./l.) as extractant the content of α-amino nitrogen, pentose, ammonia and phosphate in the extracts was studied. A marked increase in orthophosphate with age of the mycelium was found. The free amino acid pool was examined chromatographically, qualitatively and quantitatively, during growth. Glutamic acid, glutamine, alanine and proline were the principal components of this pool at all stages of growth; proline formed 40 % of this fraction at the end of the logarithmic phase of growth. Phenylalanine and tyrosine were present only in trace amounts; tryptophan was not detected in the free amino acid fraction. These three amino acids were present in mycelial protein. Glucosamine was present in increasing amounts in mycelial hydrolysates as the mould aged.

Biochemical response of the peritoneal mucosa to the irritant action of finely divided silica and other dusts.

Repeated injection of fluid suspensions of finely divided silica (quartz) into the peritoneal cavity of the rat gave rise to an increase in the concentration of lactate and α-amino nitrogen and to a decrease in the concentration of glucose in the peritoneal exudate. The silica greatly diminished the selective 'permeability' of the peritoneal membranes as evidenced by the retention of injected phenol red in the peritoneal fluid. Silica increased the concentration of trypsin inhibitor in the serum. None of these changes occurred upon repeated injection of suspensions of finely divided carbon or carborundum, or of silicic acid sol. The observations throw light on the fibrogenic action of quartz dust in silicosis.

The hydrolysis of insulin and human serum albumin in dilute hydrochloric acid

Insulin, which contains two internally situated asparagine residues and one C-terminal asparagine residue, was used as a model compound to study the specificity of protein hydrolysis in dilute hydrochloric acid. Changes occurring in aspartic acid, ammonia (arising from the hydrolysis of amide bonds), and α-amino nitrogen were determined throughout the course of hydrolysis. The results indicated that quantitative cleavage of asparagine and glutamine amide bonds and aspartic acid peptide bonds occurred. Determinations of N-terminal residues in insulin partial hydrolyzates revealed that cleavage of some serine and threonine peptide bonds occurred, but no other unexpected N-terminal residues were noted. The fragmentation in dilute acid of the proteins of the albumin fraction of human serum was studied by measuring changes in the total α-amino nitrogen content of four subfractions of albumin partial hydrolyzates, and additional evidence concerning the specificity of dilute acid hydrolysis was obtained. A peptide was isolated in good yield from an albumin dilute acid hydrolyzate and was partially characterized.

A study of the free amino acids in sweat from patients with cystic fibrosis.

There has been a paucity of work on the amino acid composition of sweat in healthy and sick children. In cystic fibrosis of the pancreas the sweat glands excrete sodium and chloride in a concentration far above that found in a control group. The potassium is also elevated but to less extent.1,2In view of this dysfunction of the sweat glands in cystic fibrosis it appeared reasonable to investigate other components of sweat. Unpublished work from this laboratory indicates that other constituents in sweat from patients with cystic fibrosis, such as urea, lactic acid, citric acid, sulfate, and phosphorus, do not differ from the normal.3It is intended in this paper to present our findings of the amino acid distribution and of the total α-amino nitrogen concentration in sweat in patients with cystic fibrosis and a control group. Rothman and Sullivan4found 11 amino acids in water-wipings

CHANGES IN INTESTINAL AND SERUM ALKALINE PHOSPHATASE LEVELS DURING ABSORPTION OF CERTAIN AMINO ACIDS

After force-feeding fasted male albino rats with solutions of amino acids it was observed that:(a) Intestinal alkaline phosphatase levels were significantly increased after ingestion of glycine, leucine, threonine, serine, glutamic acid, methionine, arginine, and large doses of glycine – glutamic acid – histidine mixtures, while a decrease was noted after force-feeding tryptophan.(b) Serum alkaline phosphatase activity was stimulated by solutions of glycine, histidine, and glutamic acid when each amino acid was given singly and even more when a mixture of these three amino acids was force-fed. Methionine on the other hand produced a highly significant depression of the activity of this enzyme.(c) Serum inorganic phosphorus levels were significantly decreased after ingestion of glycine, leucine, serine, threonine, methionine, glutamic acid, histidine, phenylalanine, tyrosine, and tryptophan.(d) Serum α-amino nitrogen concentration was increased in all cases except with cystine and lysine, when no change was observed, whereas arginine produced a highly significant drop, attributed to stimulation of urea cycle.(e) The α-amino nitrogen concentration of intestinal homogenates was increased after force-feeding glycine, leucine, cystine, methionine, glutamic acid, lysine, histidine, phenylalanine, and large amounts of glycine – histidine – glutamic acid mixtures.

CHANGES IN INTESTINAL AND SERUM ALKALINE PHOSPHATASE LEVELS DURING ABSORPTION OF CERTAIN AMINO ACIDS

After force-feeding fasted male albino rats with solutions of amino acids it was observed that:(a) Intestinal alkaline phosphatase levels were significantly increased after ingestion of glycine, leucine, threonine, serine, glutamic acid, methionine, arginine, and large doses of glycine – glutamic acid – histidine mixtures, while a decrease was noted after force-feeding tryptophan.(b) Serum alkaline phosphatase activity was stimulated by solutions of glycine, histidine, and glutamic acid when each amino acid was given singly and even more when a mixture of these three amino acids was force-fed. Methionine on the other hand produced a highly significant depression of the activity of this enzyme.(c) Serum inorganic phosphorus levels were significantly decreased after ingestion of glycine, leucine, serine, threonine, methionine, glutamic acid, histidine, phenylalanine, tyrosine, and tryptophan.(d) Serum α-amino nitrogen concentration was increased in all cases except with cystine and lysine, when no change was observed, whereas arginine produced a highly significant drop, attributed to stimulation of urea cycle.(e) The α-amino nitrogen concentration of intestinal homogenates was increased after force-feeding glycine, leucine, cystine, methionine, glutamic acid, lysine, histidine, phenylalanine, and large amounts of glycine – histidine – glutamic acid mixtures.

PRELIMINARY OBSERVATIONS ON THE COMPOSITION OF SOME AUSTRALIAN BOTTLED BEERS

An analysis of the total nitrogen and α-amino nitrogen content of seven samples of Australian bottled beer indicated an average figure of 46.3 mg. per 100 ml. and 6.9 mg. per 100 ml. respectively. Quantitative resolution of the free amino acids from three beers was effected by ion exchange chromatography. Proline was the predominant amino acid; γ-aminobutyric acid, glydne/α-alanlne, tyrosine/phenylalanlne, and the basic amino acids lysine, histldine and tryptophan were present in substantial amounts. Glutamic acid, valine, leucine and isoleucine were invariably present, while β-alanine, methionine and arginine were infrequently found. Serine, aspartic acid, threonine and asparagine were sometimes present but in very small quantities; no hydroxyproline could be detected.

RELATIVE TO THE TOTAL NITROGEN AND α-AMINO NITROGEN CONTENT OF PEPSINS OF DIFFERENT STRENGTHS: PRELIMINARY COMMUNICATION

RELATIVE TO THE TOTAL NITROGEN AND α-AMINO NITROGEN CONTENT OF PEPSINS OF DIFFERENT STRENGTHS: PRELIMINARY COMMUNICATION