Intermediate role of α-keto acids in the formation of Strecker aldehydes

Abstract We studied the specificity of kinetic methods of analysis, with emphasis on creatinine determination. The error contributed by an interferent that reacts with the analytical reagent and absorbs at the wavelength of analysis is shown to be related to the ratio of the equilibrium absorbances of the analyte and interferent, the ratio of the rate constants, the extent of the analytical reaction, and the duration of the measurement. To assess the potential diminution of the interference with kinetic methods, we determined the rate constants of several alpha-keto acids in the Jaffé reaction. Evaluation of the advantages of various measuring techniques with respect to specificity showed the main factors to be the extent of the analytical reaction and the relative value of the rate constants. Total specificity for creatine appears to be unattainable with currently used kinetic techniques.

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Studies on the synthesis and stability of α-ketoacyl peptides

Amino Acids ◽

10.1007/s00726-020-02902-8 ◽

2020 ◽

Vol 52 (10) ◽

pp. 1425-1438

Author(s):

Johann Sajapin ◽

Michael Hellwig

Keyword(s):

Peptide Bond ◽

Side Chain ◽

Peptide Backbone ◽

Post Translational Modifications ◽

Degradation Reactions ◽

Keto Acids ◽

Strecker Aldehydes ◽

The Stability ◽

Dehydration Processes ◽

Hydrolysis Of

Abstract Oxidative stress, an excess of reactive oxygen species (ROS), may lead to oxidative post-translational modifications of proteins resulting in the cleavage of the peptide backbone, known as α-amidation, and formation of fragments such as peptide amides and α-ketoacyl peptides (α-KaP). In this study, we first compared different approaches for the synthesis of different model α-KaP and then investigated their stability compared to the corresponding unmodified peptides. The stability of peptides was studied at room temperature or at temperatures relevant for food processing (100 °C for cooking and 150 °C as a simulation of roasting) in water, in 1% (m/v) acetic acid or as the dry substance (to simulate the thermal treatment of dehydration processes) by HPLC analysis. Oxidation of peptides by 2,5-di-tert-butyl-1,4-benzoquinone (DTBBQ) proved to be the most suited method for synthesis of α-KaPs. The acyl side chain of the carbonyl-terminal α-keto acid has a crucial impact on the stability of α-KaPs. This carbonyl group has a catalytic effect on the hydrolysis of the neighboring peptide bond, leading to the release of α-keto acids. Unmodified peptides were significantly more stable than the corresponding α-KaPs. The possibility of further degradation reactions was shown by the formation of Schiff bases from glyoxylic or pyruvic acids with glycine and proven through detection of transamination products and Strecker aldehydes of α-keto acids by HPLC–MS/MS. We propose here a mechanism for the decomposition of α-ketoacyl peptides.

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THE ROLE OF KETO ACIDS IN PHOTOSYNTHETIC CARBON DIOXIDE ASSIMILATION

Canadian Journal of Biochemistry and Physiology ◽

10.1139/y56-054 ◽

1956 ◽

Vol 34 (1) ◽

pp. 511-519 ◽

Cited By ~ 2

Author(s):

G. H. N. Towers ◽

D. C. Mortimer

Keyword(s):

Carbon Dioxide ◽

Amino Acids ◽

Sugar Beet ◽

Aspartic Acid ◽

Pyruvic Acid ◽

Carbon Dioxide Assimilation ◽

Free Air ◽

Keto Acids ◽

Photosynthetic Carbon

Of the keto acids identified in leaves of sugar beet and other plants exposed to C14O2, pyruvic acid was found to be the only one labelled in light periods up to 45 sec. α-Ketoglutaric and glyoxylic acids became radioactive after about 45 sec. Radioactive hydroxypyruvate was not identified under these conditions and labelled oxaloacetate was detected only in trace amounts after 60 sec. in Scenedesmus. In contrast glycine and serine were labelled after 10 sec. under comparable conditions and aspartic acid was appreciably labelled after 30 sec. The effect on the radioactivity of the keto acids of an additional period intracer-free air, with and without light, as well as the dark incorporation of C14O2 was studied. These results are discussed in relation to the role of the ketoacids in photosynthesis. It is concluded that the synthesis of amino acids such as glycine, serine, and aspartic acid may be effected by mechanisms other than transamination in green leaves in the light.

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PSXIV-19 Effect of alpha-lipoic acid on productive parameters and ruminal VFA profile in sheep

Journal of Animal Science ◽

10.1093/jas/skz258.866 ◽

2019 ◽

Vol 97 (Supplement_3) ◽

pp. 437-438

Author(s):

Carolina Robles ◽

Laura Gonzáles Davalos ◽

Ofelia Mora ◽

Yesmin Hermanadez ◽

Armando Shimada ◽

...

Keyword(s):

Blood Glucose ◽

Lipoic Acid ◽

Insulin Receptors ◽

Daily Weight Gain ◽

Oxidative Decarboxylation ◽

Alpha Lipoic Acid ◽

Randomized Design ◽

Keto Acids ◽

Mechanism Research

Abstract Alpha lipoic acid (LA) is a potent nutritional antioxidant. It is a derivate of octanoic acid containing a cyclic disulfide bond. An LA complex with lysine-lipoamide, functions as a co-factor in the mitochondrial dehydrogenase that catalyzes the oxidative decarboxylation of α-keto acids. In this reaction, LA is reduced to dihydrolipoic acid (DHLA), which interacts with reactive oxygen species, and LA can also inactivate free radicals. Another important role of DHLA is in signal transduction by activating insulin receptors, which causes glucose transporters translocation from cytoplasm to the cell surface. Due to its potential antioxidant effect at ruminal level, the aim of this study was to evaluate the effect of fed LA on productive parameters, ruminal fatty volatile fatty acid (VFA) concentration and blood glucose of sheep. Sixty-four, two-months-old, crossbred lambs were penned in groups of four, divided into four treatments: 0, 40, 80, and 120 ppm LA in diet. During 84 days, every 28 days on two consecutive days, animals were weighed (to determine average daily weight gain, DWG), blood and ruminal fluid were taken for glucose and VFA quantification, respectively. All variables were analyzed in a completely randomized design. DWG was statistically higher in those animals receiving 80 ppm (250 g) as compared to the rest (200, 188, 180 g for 120, 40, 0 ppm, respectively) (P < 0.0001). No differences in blood glucose or ruminal VFA were found (P > 0.1). LA could improve the productive performance of sheep; however, it would be necessary to study the role of LA and its effects on the ruminal microbiome and its action mechanism. Research support by Project PAPIIT-UNAM IN211518

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Intermediate Role of Gallium in Oxidic Glasses: Solid State NMR Structural Studies of the Ga2O3–NaPO3System

The Journal of Physical Chemistry C ◽

10.1021/jp504023k ◽

2014 ◽

Vol 118 (28) ◽

pp. 15386-15403 ◽

Cited By ~ 24

Author(s):

Jinjun Ren ◽

Hellmut Eckert

Keyword(s):

Solid State ◽

Solid State Nmr ◽

Structural Studies ◽

Intermediate Role

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An early intermediate in the biosynthesis of biotin: Incorporation studies with [1,7-14C2]pimelic acid

Biochemical Journal ◽

10.1042/bj1010601 ◽

1966 ◽

Vol 101 (3) ◽

pp. 601-606 ◽

Cited By ~ 6

Author(s):

M A Eisenberg ◽

R Maseda

Keyword(s):

Penicillium Chrysogenum ◽

Pimelic Acid ◽

Culture Filtrates ◽

High Yields ◽

Intermediate Role

1. An unknown biotin vitamer was obtained in high yields in culture filtrates of Penicillium chrysogenum. 2. Production of this vitamer and desthiobiotin is controlled by the biotin concentration in the medium. 3. The unknown vitamer becomes labelled when the organism is grown in the presence of radioactive pimelic acid. 4. Chromatographic procedures were developed for the purification of the radioactive vitamer. 5. The vitamer is extremely stable in concentrated acid but gives rise to new vitamers under certain conditions. 6. The intermediate role of this vitamer in the synthesis of biotin is discussed.

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The Intermediate Role of Organizational Flexibility in the Impact of Using Information Technology on the Efficiency of the Application of IT Governance in Jordanian Industrial Companies

Modern Applied Science ◽

10.5539/mas.v14n7p75 ◽

2020 ◽

Vol 14 (7) ◽

pp. 75

Author(s):

Hamzeh Mohamed Al-Hawamdeh

Keyword(s):

Information Technology ◽

It Governance ◽

Organizational Flexibility ◽

Intermediate Variable ◽

Industrial Companies ◽

Stratified Sample ◽

Comprehensive Survey ◽

The Impact ◽

Intermediate Role

The current study aimed to identify the intermediate role of organizational flexibility in the impact of using information technology on the efficiency of the application of IT governance in Jordanian industrial companies, the study population consisted of all Jordanian industrial companies which by the end of 2019 were (56) company. (23) company were excluded due to the lack of access to the necessary data for the study, bringing the study sample size to (33) company. Due to the small size of the study sample, all companies were taken with a comprehensive survey, and a random stratified sample was adopted to determine the size of the study sample in each company. Where the inspection unit included individuals working in the upper and middle administrative levels in Jordanian industrial companies. Multiple linear correlation test was used along with simple and gradient test , as well as Path Analysis using (Amos) And supported by the Statistical Package for Social Sciences (SPSS) program, the study reached many results, the most important of which was an indirect impact of the dimensions of the use of (information technology) combined ; in the efficiency of the application of IT governance with the presence of organizational flexibility as an intermediate variable among Jordanian industrial companies, as for the recommendations, it is necessary to find an organizational consistency between the uses of information technology in light of the use of COBIT 5 applications and guidelines in the presence of organizational flexibility, because it will help to adapt to unexpected crises and invest Opportunities for industrial companies at the local and global levels.

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