The effect of thiourea and formaldehyde treatment on the chemical analysis of wool. II. Amino acid analyses

1970 ◽  
Vol 23 (3) ◽  
pp. 533 ◽  
Author(s):  
PW Nicholls ◽  
LC Gruen
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Chemical Analysis ◽  
Acid Hydrolysis ◽  
New Technique ◽  
Formaldehyde Treatment ◽  
A New Technique

The anomalous amino acid analyses obtained for some amino acids, from the hydrolysates of thiourea-formaldehyde and formaldehyde-treated wool samples, are due largely to reactions with formaldehyde during acid hydrolysis. A new technique has been developed, involving hydrolysis in refluxing hydrochlorio acid in an atmosphere of nitrogen. This method improves the recovery of amino acids and has also been of assistance in explaining the abnormal analyses observed for oystine, tyrosine, lysine, and threonine in the presence of formaldehyde.

scholarly journals Amino acid availability: aspects of chemical analysis and bioassay methodology

2003 ◽  
Vol 16 (2) ◽  
pp. 127-141 ◽  
Author(s):  
Paul J. Moughan
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Chemical Analysis ◽  
Structural Damage ◽  
Human Subjects ◽  
Scientific Evidence ◽  
Hydrolysis Time ◽  
Amino Acid Availability

AbstractIt is important to be able to characterise foods and feedstuffs according to their available amino acid contents. This involves being able to determine amino acids chemically and the conduct of bioassays to determine amino acid digestibility and availability. The chemical analysis of amino acids is not straightforward and meticulousness is required to achieve consistent results. In particular and for accuracy, the effect of hydrolysis time needs to be accounted for. Some amino acids (for example, lysine) can undergo chemical modification during the processing and storage of foods, which interferes with amino acid analysis. Furthermore, the modified amino acids may also interfere with the determination of digestibility. A new approach to the determination of available lysine using a modifiedin vivodigestibility assay is discussed. Research is required into other amino acids susceptible to structural damage. There is recent compelling scientific evidence that bacterial activity in the small intestine of animals and man leads to the synthesis and uptake of dietary essential amino acids. This has implications for the accuracy of the ileal-based amino acid digestibility assay and further research is required to determine the extent of this synthesis, the source of nitrogenous material used for the synthesis and the degree of synthesis net of amino acid catabolism. Although there may be potential shortcomings in digestibility assays based on the determination of amino acids remaining undigested at the terminal ileum, there is abundant evidence in simple-stomached animals and growing evidence in human subjects that faecal-based amino acid digestibility coefficients are misleading. Hindgut microbial metabolism significantly alters the undigested dietary amino acid profile. The ileal amino acid digestibility bioassay is expected to be more accurate than its faecal-based counterpart, but correction of the ileal amino acid flow for amino acids of endogenous origin is necessary. Approaches to correcting for the endogenous component are discussed.

Comparison of some properties of soil humic acids and synthetic phenolic polymers incorporating amino derivaties

Soil Research ◽  
1966 ◽  
Vol 4 (1) ◽  
pp. 41 ◽  
Author(s):  
JN Ladd ◽  
JHA Butler
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Acid Hydrolysis ◽  
Humic Acids ◽  
Gel Filtration ◽  
Quinone Imine ◽  
Peptide Bonds ◽  
Molecular Weights ◽  
Soil Humic Acids ◽  
Properties Of Soil

Twenty-three model phenolic polymers, either nitrogen-free or incorporating amino acids, peptides, or proteins, have been prepared from p-benzoquinone and catechol under mild oxidative conditions. Two lines of experimentation have demonstrated properties of soil humic acids closely similar to those of polymers incorporating proteins, but different from those of polymers incorporating amino acids: (1) fractionation of humic acids and synthetic polymers by 'Sephadex' gel filtration showed that the percentage of components of molecular weights nominally greater than 100 000 ranged from 52-76 % for eight humic acids tested, 53-59 % for benzoquinone-protein polymers (excluding polymers containing protamine), but less than 20% for all other polymers; (2) acid hydrolysis with 6M HCl resulted in a partial release of polymer nitrogen. Amino acid nitrogen in the hydrolysates accounted for 32.4-51.9 % of humic acid nitrogen, 31.2-56.3 % of the nitrogen of polymers incorporating protein, but less than 10.8% of the nitrogen of polymers incorporating individual amino acids. Experiments with model monomeric N-phenylglycine derivatives and with polymers incorporating simple peptides showed that the bond between the carbon atom of an aromatic ring and the nitrogen atom of an a-amino acid is far more stable to acid hydrolysis than peptide bonds or bonds linking amino acids in humic acids. Glycine is, however, readily released from N-phenylglycine derivatives when conditions favour their oxidation to a quinone-imine intermediate. Incorporation of proteins into phenolic polymers prevented the detection of peptide bonds by the Folin reagent.

scholarly journals Studies on the nitrogen compounds of the faeces of dairy cows fed urea as the sole or partial source of nitrogen

1979 ◽  
Vol 51 (1) ◽  
pp. 506-513
Author(s):  
Terttu Ettala ◽  
Matti Kreula
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Dairy Cows ◽  
Acid Hydrolysis ◽  
Free Amino Acid ◽  
Total Nitrogen ◽  
Free Amino ◽  
Diaminopimelic Acid ◽  
Nitrogen Compounds ◽  
Soluble Nitrogen

The nitrogen compounds of the faeces of dairy cows on purified, protein-free feed with urea and small amounts of ammonium salts as the sole source of nitrogen (0-feed). on low-protein feed in which part of the protein was replaced with urea (ULP-feed) and on normal protein-containing feed (NorP-feed) were studied. The total nitrogen contents of the dry matter of the faeces were 2.5 ± 0.7 % on 0-feed, 2.4 ± 0.4 % on ULP-feed and 2.3 ± 0.6 % on NorP-feed. The proportion of urea- and ammonium nitrogen of the total nitrogen was 3.2 ± 2.4, 4.5 ± 2.4 and 3.7 ± 1.8 % respectively, and the proportion of nitrogen soluble in 70 % ethanol 10.9 ± 5.7, 9.9 ± 2.4 and 10.4 ± 3.8 % of the total nitrogen; the proportion of nitrogen in the free amino acid fraction was 4.1 ±2.9 on 0-feed, 1.6 ± 1.4 (P < 0.05) on ULP-feed and 3.2 ± 2.9 % on NorP-feed. The nitrogen insoluble in 70 % ethanol as a proportion of the total nitrogen was 82.3 ± 7.2 on 0-feed, 85.4 ± 5.0 on ULP-feed and 82.3 ± 7.2 % on NorP-feed. Of the total nitrogen of this insoluble fraction, the following proportions were released as amino acids by acid hydrolysis: 62.15 ± 8.5 % on 0-feed, 61.6 ± 10.7 % on ULP-feed and 59.0 ± 13.9% on NorP-feed. (α, Ɛ-diaminopimelic acid was 1.7 ± 0.6, 0.7 ± 0.2 (P < 0.05) and 1.2 ± 0,4 mol % respectively of the total amino acids of the hydrolyzate. The soluble nitrogen fraction was separated into free amino acid and »peptide» fractions, and the amino acid composition of both was determined, the latter after acid hydrolysis

D-Mannitol Interferes with Amino Acid Analysis of Marine Organisms

1979 ◽  
Vol 36 (9) ◽  
pp. 1134-1137 ◽  
Author(s):  
W. Fong ◽  
R. K. O'dor
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Acid Hydrolysis ◽  
Key Words ◽  
Amino Acid Analysis ◽  
Chromatographic Analysis ◽  
Marine Algae ◽  
Protein S ◽  
New Compounds ◽  
Hydrolysis Of

Acid hydrolysis of a protein in the presence of D-mannitol, a common constituent of marine algae, can cause significant reductions in the recovery of a number of amino acids. The new compounds formed by the interactions of D-mannitol and these amino acids may interfere in the chromatographic analysis of other amino acids. The recoveries of most of the amino acids appear to be either directly or inversely proportional to the amount of D-mannitol added to a protein sample before acid hydrolysis. These results suggest that it is necessary to determine the effects of contaminants in a sample of protein(s) on the recoveries of amino acids during routine acid hydrolysis. Key words: kelp, amino acids, carbohydrates, D-mannitol

Net fluxes of peptide and amino acid across mesenteric-drained and portal-drained viscera of yak cows fed a straw-concentrate diet at maintenance level

2001 ◽  
Vol 136 (1) ◽  
pp. 119-127 ◽  
Author(s):  
XING-TAI HAN ◽  
BAI XUE ◽  
JI-ZENG DU ◽  
LING-HAO HU
Keyword(s):  
Amino Acids ◽  
Blood Flow ◽  
Amino Acid ◽  
Acid Hydrolysis ◽  
Portal Blood Flow ◽  
Mesenteric Vein ◽  
Before And After ◽  
The Difference ◽  
Net Fluxes ◽  
Net Release

The present experiment was conducted to quantify the net fluxes of both free and peptide amino acids across the mesenteric and stomach portions of the portal-drained viscera (PDV) of three yak cows (172·3±18·6 kg, BW) fed a straw-concentrate diet at maintenance level. Yaks had been fitted with sampling catheters in the portal vein, mesenteric artery and mesenteric vein prior to its convergence with the gastrosplenic vein. Blood flow was determined by measuring the dilution of para-aminohippurate (PAH) infused constantly into a distal mesenteric vein. Amino acids in the deproteinized plasma were analysed before and after acid hydrolysis. The increased amino acids after acid hydrolysis were considered as peptide-bound amino acids (PAA). The fluxes of free amino acids (FAA) and PAA across PDV and mesenteric-drained viscera (MDV) were calculated as the product of venoarterial differences and plasma flow. Flux across the stomach viscera (SDV) was calculated as the difference between portal and mesenteric fluxes. Portal blood flow was 389 l/h or 2·32 l/h kg BW, of which 37% was contributed by the mesenteric vein. There was net appearance of a large quantity of PAA across PDV, which accounted for 92% of the total nonprotein amino acid flux. Net release of PAA and FAA in SDV accounted for 78% and 42% of the net release in PDV, respectively. These results suggest that in yaks, peptide possibly is the primary form of amino acid absorption, and that the stomach area probably is the major site of peptide absorption.

INCORPORATION OF C14INTO BACTERIAL PEPTIDES

1958 ◽  
Vol 4 (6) ◽  
pp. 633-648 ◽  
Author(s):  
G. E. Connell ◽  
R. W. Watson
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Acid Hydrolysis ◽  
High Voltage ◽  
Basic Amino Acid ◽  
Paper Electrophoresis ◽  
Total Radioactivity ◽  
Before And After ◽  
Basic Peptides ◽  
Peptide Fractions

Alcoholic extracts of log-phase cells of Pseudomonas hydrophila grown on glucose as the sole carbon source were concentrated, extracted with ether, and dialyzed. After fractionation of the permeates by high voltage paper electrophoresis, five to seven ninhydrin-positive acidic, one neutral, and several basic bands appeared. As many as seven ninhydrin-positive basic bands have been found in some preparations, although they have been absent in others. Photometric analyses on eluates before and after acid hydrolysis indicated the presence of acidic, neutral, and basic peptides. Amino acid compositions of 28 of these peptides, separated by a combination of high voltage paper electrophoresis and paper chromatography, included all of the amino acids commonly found in proteins. Elution of acidic, neutral, and basic amino acid and peptide fractions from C14-labelled cells was followed by measurement of total and specific radioactivities in carboxyl-C before and after acid hydrolysis. Total radioactivity was highest in proteins even 1 minute after addition of the isotope to a log-phase culture. Specific radioactivities, plotted against time, gave parallel hyperbolic curves with peptides below the curve for amino acids and with proteins still lower and almost linear. The evidence suggests rapid synthesis of peptides from amino acids.

ACTION OF PROTEOLYTIC ENZYMES ON SOIL ORGANIC MATTER

1970 ◽  
Vol 50 (2) ◽  
pp. 233-241 ◽  
Author(s):  
F. J. SOWDEN
Keyword(s):  
Amino Acids ◽  
Organic Matter ◽  
Amino Acid ◽  
Soil Organic Matter ◽  
Acid Hydrolysis ◽  
Leucine Aminopeptidase ◽  
Proteolytic Enzymes ◽  
Complexing Agent ◽  
Organic Matter Fractions ◽  
Hydrolysis Of

The amino acids set free by proteolytic enzymes were determined with an amino acid analyzer. Soil and enzyme blanks were subtracted. Pronase released 2 to 10% of the aspartic acid + asparagine, threonine, serine, glutamic acid + glutamine, glycine, lysine and histidine in some fractions of soil organic matter along with 15–35% of the alanine, valine, isoleucine, leucine, tyrosine, phenylalanine and arginine. There was no release of proline, ornithine or ammonia. When the pronase hydrolysate was treated with leucine amino-peptidase, 15% of the proline was released, the yield of glycine was raised from 2 to 14% and the amount of the acidic amino acids was also higher. Acid hydrolysis of the pronase hydrolysate also released more amino acid material but the blanks were much higher than with leucine aminopeptidase. The results suggested that more than half of the aspartic and glutamic acids found on acid hydrolysis were present in the soil organic matter fractions as asparagine and glutamine. The action of pronase on the organic matter of the intact soil was slight, even in the presence of a complexing agent. Papain released very little amino acid material from organic matter fractions, but leucine aminopeptidase or HCl hydrolysis of the papain hydrolysate released about 10% of the amino acid of the fraction, indicating that significant amounts of peptides were formed on papain treatment.

The influence of formic acid and formaldehyde additives and type of harvesting machine on the utilization of nitrogen in lucerne silages: 2. Changes in amino-acid composition during ensiling and their influence on nutritive value

1978 ◽  
Vol 91 (3) ◽  
pp. 717-725 ◽  
Author(s):  
T. N. Barry ◽  
D. N. Mundell ◽  
R. J. Wilkins ◽  
D. E. Beever
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Formic Acid ◽  
Glutamic Acid ◽  
Amino Acid Composition ◽  
Aspartic Acid ◽  
Nutritive Value ◽  
Formaldehyde Treatment ◽  
Amino Acid Degradation ◽  
Voluntary Intake

SummaryLucerne was made into ten silages using either a flail or a precision-chop harvester with application of formaldehyde or a range of rates of formic acid during harvesting. Amino-acid analyses were done on the silages and on samples taken from the herbage at ensiling.In excess of 70% of aspartic acid, serine, glutamic acid, tyrosine, threonine, lysine, histidine and arginine were destroyed in untreated silages when a flail harvester was used and in excess of 50% when a precision-chop harvester was used. Glycine, leucine, iso-leucine, valine and methionine showed little change, with net losses or increases of up to 10%, whilst proline, cystine + cysteine and phenylalanine were intermediate between these two categories. Net synthesis of alanine and α and γ amino-butyric acids occurred in the untreated silages. Increasing rates of formic acid addition, and the use of the precision-chop harvester, reduced the loss of the amino acids which were extensively degraded in the untreated silages and minimized the increases in alanine and α and γ amino-butyric acids. Formaldehyde treatment also reduced amino-acid degradation, apart from apparently high losses of lysine, histidine and tyrosine. It was concluded, however, that these losses arose through problems of estimation in formaldehyde-treated silages following HCl hydrolysis.It is suggested that the most probable precursors for alanine and α and γ aminobutyric acids were respectively aspartic acid, threonine and glutamic acid. Voluntary intake and the utilization of silage nitrogen by young sheep were related to the net changes in amino acids involved in decarboxylation reactions, the best measures of this being the interconversions involving the formation of alanine and α and γ aminobutyric acids. Deamination reactions appeared to be of much less importance in limiting silage nutritive value than those involving decarboxylation.

scholarly journals Prealamethicin F50 and related peptaibols from Trichoderma arundinaceum: validation of their authenticity via in situ chemical analysis

RSC Advances ◽  
2017 ◽  
Vol 7 (72) ◽  
pp. 45733-45741 ◽  
Author(s):  
José Rivera-Chávez ◽  
Huzefa A. Raja ◽  
Tyler N. Graf ◽  
Jacklyn M. Gallagher ◽  
Prashant Metri ◽  
...  
Keyword(s):  
Secondary Metabolites ◽  
Chemical Analysis ◽  
New Technique ◽  
A New Technique

A new technique was used to monitor the chemistry of fungal cultures in situ, thereby confirming authenticity of secondary metabolites.

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