Chloroperoxidase-catalyzed oxidation of methionine derivatives

2002 ◽  
Vol 80 (6) ◽  
pp. 633-639 ◽  
Author(s):  
Herbert L Holland ◽  
Frances M Brown ◽  
Damian Lozada ◽  
Benjamin Mayne ◽  
W Rick Szerminski ◽  
...  
Keyword(s):  
Enzyme Catalysis ◽  
Acid Oxidation ◽  
Amino Acid Oxidation ◽  
Subtilisin Carlsberg ◽  
Key Words Amino Acid ◽  
Aspergillus Sp ◽  
Oxidation Of Methionine ◽  
Derivatives Of ◽  
Diastereomeric Excess ◽  
Catalyzed Oxidation

Treatment of N-methoxycarbonyl C-carboxylate ester derivatives of L- and D-methionine and L-ethionine by chloroperoxidase–hydrogen peroxide resulted in oxidation at sulfur to produce the (RS) sulfoxide in moderate to high diastereomeric excess. The (RS) sulfoxide of methionine was also obtained in moderate to high diastereomeric excess from (±)SO-N-methoxycarbonyl-L-methionine methyl ester sulfoxide by ester hydrolysis using α-chymotrypsin, Aspergillus sp. protease or subtilisin Carlsberg. Key words: amino acid oxidation, biocatalysis, biotransformation, chloroperoxidase, enzyme catalysis, lipase, sulfoxidation.

Roles of urea production, ammonium excretion, and amino acid oxidation in acid-base balance

1986 ◽  
Vol 250 (2) ◽  
pp. F181-F188 ◽  
Author(s):  
W. Mackenzie
Keyword(s):  
Amino Acid ◽  
Acid Oxidation ◽  
Ammonium Excretion ◽  
Acid Base Balance ◽  
Acid Base ◽  
Amino Acid Oxidation ◽  
Titratable Acid ◽  
Urea Production ◽  
Base Balance ◽  
Oxidation Of Methionine

Atkinson and colleagues recently proposed several concepts that contrast with traditional views: first, that acid-base balance is regulated chiefly by the reactions leading to urea production in the liver; second, that ammonium excretion by the kidney plays no role in acid-base homeostasis; and third, that ammonium does not stimulate ureagenesis (except indirectly). To examine these concepts, plasma ions other than bicarbonate are categorized as 1) fixed cations (Na+, K+, Ca2+, and Mg2+, symbolized M+) and anions (Cl-), 2) buffer anions (A-), 3) other anions (X-), and 4) ammonium plus charged amino groups (N+). Since electroneutrality dictates that M+ + N+ = Cl- + HCO3- + A- + X-, it follows that delta HCO3- = delta(M+ - Cl-) - delta A- - delta X- + delta N+. Therefore acid-base disturbances (changes in HCO3-) can be categorized as to how they affect bodily content and hence plasma concentration of each of these four types of ions. The stoichiometry of ureagenesis, glutamine hydrolysis, ammonium and titratable acid excretion, oxidation of neutral, acidic, and basic amino acids, and oxidation of methionine, phosphoserine, and protein are examined to see how they alter these quantities. It is concluded that 1) although ureagenesis is pH dependent and also counteracts a tendency of amino acid oxidation to cause alkalosis, this tendency is inherently limited by the hyperammonemia (delta N+) that necessarily accompanies it, 2) ammonium excretion is equivalent to hydrogen excretion in its effects on acid-base balance if, and only if, it occurs in exchange for sodium or is accompanied by chloride excretion and only when the glutamate generated by glutamine hydrolysis is oxidized.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals PSXI-31 Program Chair Poster Pick: Determination of the threonine requirement in adult and senior Labrador Retrievers using the indicator amino acid oxidation technique

2020 ◽  
Vol 98 (Supplement_4) ◽  
pp. 321-322
Author(s):  
Jordan T Weil ◽  
Jessica L Varney ◽  
Jason W Fowler ◽  
Craig N Coon
Keyword(s):  
Amino Acid ◽  
Control Diet ◽  
Genetic Selection ◽  
Isotope Ratio Mass Spectrometry ◽  
Acid Oxidation ◽  
Amino Acid Oxidation ◽  
Amino Acid Requirements ◽  
Indispensable Amino Acids ◽  
Nutrient Profiles ◽  
Labrador Retrievers

Abstract Although nutrient profiles for canines have been developed in the past, the need to update amino acid (AA) requirements has gained importance as genetic selection changes the recommended nutrients. Correctly feeding AA to canines can have enormous effects, considering a deficiency or excess of such nutrient can lead to weight loss, disease, or in some cases, death. Amino acid requirements can be determined through the nitrogen balance or indicator amino acid oxidation (IAAO) methods. In this experiment, the IAAO technique was used to determine the threonine (Thr) requirement in Labrador retrievers. A total of six dogs (6 adult and 6 senior) were subjected to six diets with varying levels of Thr, ranging from deficient to excess. Diets were formulated to 1.6x NRC values for all indispensable amino acids. The control diet was fed for two days, followed by a day in which the test diet was fed, a tracer AA was supplied, and breath samples were collected. On test day, a priming dose of L-[1-13C]phenylalanine (Cambridge Isotope Laboratories, Inc.) based on the subject’s body weight was first supplied, followed by [1-13C]Phe doses every thirty minutes, spanning a four hour period. A respiration mask was placed on each subject every thirty minutes (Oxymax, Columbus Instruments), 13CO2 was collected, and enrichment was determined by isotope ratio mass spectrometry (IRMS). Results for IRMS were converted to atom percent excess (APE) and analyzed using a piecewise model of best fit (JMP® Pro 15). The segmented line regression showed that the Thr mean and population requirements were determined to be 1.21 ± 0.24 and 0.92 ± 0.17 g/1000kcal (mean ± 2SD) for adult and senior dogs, respectively. As the pet food industry becomes more specialized in diets relating to aging, and diseased canines, updating the amino acid requirements related to such animals is increasingly important.

scholarly journals Phenylalanine requirement in children with classical PKU determined by indicator amino acid oxidation

2002 ◽  
Vol 283 (6) ◽  
pp. E1249-E1256 ◽  
Author(s):  
Glenda Courtney-Martin ◽  
Rachelle Bross ◽  
Mahroukh Raffi ◽  
Joe T. R. Clarke ◽  
Ronald O. Ball ◽  
...  
Keyword(s):  
Amino Acid ◽  
Acid Oxidation ◽  
Phenylalanine Concentration ◽  
Two Phase ◽  
Amino Acid Oxidation ◽  
Blood Phenylalanine ◽  
Plasma Phenylalanine ◽  
Crossover Analysis ◽  
The Mean ◽  
The Difference

Dietary restriction of phenylalanine is the main treatment for phenylketonuria (PKU), and current estimates of requirements are based on plasma phenylalanine concentration and growth. The present study aimed to determine more precisely the phenylalanine requirements in patients with the disease by use of indicator amino acid oxidation, withl-[1-13C]lysine as the indicator. Breath13CO2 production (F13 co 2) was used as the end point. Finger-prick blood samples were also collected for measurement of phenylalanine to relate phenylalanine intake to blood phenylalanine levels. The mean phenylalanine requirement, estimated using a two-phase linear regression crossover analysis, was 14 mg · kg−1 · day−1, and the safe population intake (upper 95% confidence interval of the mean) was found to be 19.5 mg · kg−1 · day−1. A balance between phenylalanine intake and the difference between fed and fasted blood phenylalanine concentration was observed at an intake of 20 mg · kg−1 · day−1. The similarity between these two values (19.5 and 20 mg · kg−1 · day−1) suggests that the maximal phenylalanine intake for children with PKU should be no higher than 20 mg · kg−1 · day−1.

scholarly journals Threonine requirements of healthy Indian men, measured by a 24-h indicator amino acid oxidation and balance technique

2002 ◽  
Vol 76 (4) ◽  
pp. 789-797 ◽  
Author(s):  
Anura V Kurpad ◽  
Tony Raj ◽  
Meredith M Regan ◽  
Jahnavi Vasudevan ◽  
Brinnell Caszo ◽  
...  
Keyword(s):  
Amino Acid ◽  
Acid Oxidation ◽  
Amino Acid Oxidation ◽  
Balance Technique ◽  
Indian Men

scholarly journals Protein requirement of elderly women determined using the indicator amino acid oxidation technique

2012 ◽  
Vol 26 (S1) ◽  
Author(s):  
Minghua Tang ◽  
George P McCabe ◽  
Rajavel Elango ◽  
Paul B Pencharz ◽  
Ronald O Ball ◽  
...  
Keyword(s):  
Amino Acid ◽  
Elderly Women ◽  
Acid Oxidation ◽  
Protein Requirement ◽  
Amino Acid Oxidation
Sign in / Sign up

Export Citation Format

Share Document