scholarly journals Effects of Aminoguanidine and Pyridoxal Phosphate on Glycation Reaction of Aspartate Aminotransferase and Serum Albumin.

1995 ◽  
Vol 41 (1) ◽  
pp. 43-50 ◽  
Author(s):  
Mitsuko OKADA ◽  
Yuki AYABE
Keyword(s):  
Serum Albumin ◽  
Aspartate Aminotransferase ◽  
Pyridoxal Phosphate

The C-S lysis of L-cysteine conjugates by aspartate and alanine aminotransferase enzymes

1995 ◽  
Vol 14 (5) ◽  
pp. 422-427 ◽  
Author(s):  
Peter J Gaskin ◽  
Harriet J Adcock ◽  
Lorraine D Buckberry ◽  
Paul H Teesdale-Spittle ◽  
P Nicholas Shawl
Keyword(s):  
Aspartate Aminotransferase ◽  
Alanine Aminotransferase ◽  
Pyridoxal Phosphate ◽  
Enzyme Inhibitor ◽  
Potential Interaction ◽  
Direct Inhibition ◽  
Porcine Heart ◽  
Lyase Activity ◽  
Oxyacetic Acid ◽  
Dependent Mechanism

One biotransformation pathway which is responsible for the generation of mutagenic and cytotoxic metabolites is that of the C-S lysis (CSL) of L-cysteine conjugates. Thirteen cysteine S-conjugates, synthesised in our labora tories, were incubated with porcine heart aspartate aminotransferase (ASAT) and alanine aminotransferase (ALAT), and the C-S lyase activity for each enzyme-sub strate combination was determined. ASAT and ALAT were shown to exhibit CSL activity. It was also demonstrated that this activity was inhibited in the presence of the pyri doxal phosphate (PLP)-dependent enzyme inhibitor amino(oxyacetic acid) (AOAA) confirming the pyridoxal phosphate dependent mechanism by which C-S lysis is known to take place. Since the activities of these enzymes are used as biomarkers for the assessment of organ dam age, the potential interaction of L-cysteine conjugates with them may suppress their activity through direct inhibition.

Low serum albumin, aspartate aminotransferase, and body mass are risk factors for frailty in elderly people with diabetes: possible mechanistic role of dehydroepiandrosterone sulfate – a cross-sectional study

2020 ◽  
Author(s):  
Toshihiko Yanase ◽  
Ikumi Yanagita ◽  
Yuya Fujihara ◽  
Chikayo Iwaya ◽  
Yuichi Kitajima ◽  
...  
Keyword(s):  
Risk Factors ◽  
Regression Analysis ◽  
Serum Albumin ◽  
Body Mass ◽  
Aspartate Aminotransferase ◽  
Dehydroepiandrosterone Sulfate ◽  
Cross Sectional Study ◽  
Sectional Study ◽  
Cross Sectional ◽  
Independent Risk Factors

Abstract Background: Relatively low dehydroepiandrosterone sulfate (DHEA-S) and high cortisol/DHEA ratio have been suggested to be associated with frailty, evaluated using a physical scale. However, the significance of these two hormones for frailty in elderly patients with type 2 diabetes mellitus (T2DM) has not been assessed using a wider range of measures of frailty, including physical, mental, and social indices. Methods: We performed a cross-sectional study to investigate the significance of these two hormones for frailty in elderly T2DM patients (n=148; ≥65 years), using a broad assessment, the clinical frailty scale, and to reevaluate the risk factors for frailty in elderly T2DM patients. We compared parameters between the non-frail and frail groups using the unpaired t and Mann-Whitney U tests. The Jonckheere-Therpstra test was used to identify relationships with the severity of frailty and risk factors were identified using binary regression analysis. Results: Simple regression analysis identified a number of significant risk factors for frailty, including DHEAS <70 µg/dL and cortisol/DHEA-S ratio ≥0.2. Multiple regression analysis showed that low albumin (<4.0 g/dl) (odds ratio [OR]=5.79, p <0.001), low aspartate aminotransferase (AST) activity (<25 IU/L) (OR=4.34, p =0.009), and low body mass (BM) (<53 kg) (OR=3.85, p =0.012) were independent risk factors for frailty. A significant decrease in DHEA-S and a significant increase in the cortisol/DHEA-S ratio occurred alongside increases in the severity of frailty. DHEA-S concentration positively correlated with both serum albumin and BM. Conclusions: Hypoalbuminemia, low AST, and low BM are independent risk factors for frailty in elderly T2DM patients, strongly implying relative malnutrition in these frail patients. DHEA-S may be important for the maintenance of liver function and BM. A decrease in DHEA-S and an increase in the cortisol/DHEAS ratio may be involved in the mechanism of the effect of malnutrition in elderly T2DM patients.

Interlaboratory Study of the IFCC Method for Alanine Aminotransferase Performed with Use of a Partly Purified Reference Material

1992 ◽  
Vol 38 (12) ◽  
pp. 2365-2371 ◽  
Author(s):  
F Schiele ◽  
J Muller ◽  
E Colinet ◽  
G Siest ◽  
P Arzoglou ◽  
...  
Keyword(s):  
Reference Material ◽  
Bovine Serum Albumin ◽  
Confidence Interval ◽  
Serum Albumin ◽  
Enzyme Activities ◽  
Aspartate Aminotransferase ◽  
Alanine Aminotransferase ◽  
Bovine Serum ◽  
Specific Activity ◽  
Interlaboratory Trial

Abstract We present the results of a study on performance of a reference material for alanine aminotransferase (ALT, EC 2.6.1.2) and the corresponding IFCC-approved method in an interlaboratory trial involving 13 laboratories. The ALT material was partly purified from pig heart (specific activity, 150 kU/g) and was essentially free of six potentially contaminating enzyme activities, including aspartate aminotransferase (EC 2.6.1.1). The partly purified ALT was lyophilized in a triethanolamine-buffered matrix, pH 6.4, containing bovine serum albumin and saccharose. Under these conditions, the predicted yearly loss of activity was 0.02% at 4 degrees C and &lt; 0.01% at -20 degrees C. The final blank-corrected results of the accepted set of data gave a mean (SD) of 128.5 (5.1) U/L. The among-laboratory SD was 4.6 U/L and the within-laboratory SD was 2.0 U/L. The certified ALT catalytic concentration in the reconstituted material was 129 U/L with a 0.95 confidence interval of +/- 4 U/L.

scholarly journals N-(5′-Phosphopyridoxyl)glutamic acid and N-(5′-phosphopyridoxyl)-2-oxopyrrolidine-5-carboxylic acid and their action on the apoenzyme of aspartate aminotransferase

1971 ◽  
Vol 124 (1) ◽  
pp. 99-106 ◽  
Author(s):  
R M. Khomutov ◽  
H B. F. Dixon ◽  
L V. Vdovina ◽  
M P. Kirpichnikov ◽  
Y V. Morozov ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Carboxylic Acid ◽  
Glutamic Acid ◽  
Aspartate Aminotransferase ◽  
Fluorescence Spectra ◽  
Pyridoxal Phosphate ◽  
Hydroxyl Group ◽  
Side Chain ◽  
Compound I ◽  
Compound Ii

1. N-(5′-Phosphopyridoxyl)-l-glutamic acid (P-Pxy-Glu, compound I) is readily converted at pH3 into a substance (P-Pxy-Glp, compound II) characterized as N-(5′-phosphopyridoxyl)-2-oxopyrrolidine-5-carboxylic acid. 2. The u.v., i.r. and fluorescence spectra of P-Pxy-Glu and P-Pxy-Glp have been determined; from the u.v. spectra their pK values have been found and compared. 3. The apoenzyme of aspartate aminotransferase is rapidly and irreversibly inactivated by P-Pxy-Glu, but is inactivated more slowly by P-Pxy-Glp. The complex with P-Pxy-Glp is stable enough to be isolated, but it is slowly reactivated in the presence of excess of pyridoxal phosphate. 4. The u.v. spectrum of the complex of apoenzyme and P-Pxy-Glp suggests that it contains a hydrogen bond between the phenolic hydroxyl group and the pyrrolidone nitrogen; this specifies the conformation of most of the molecule of P-Pxy-Glp. This conformation is similar to that previously postulated for the enzyme–glutamate complex except for the side chain of glutamate. Hence both the affinity of P-Pxy-Glp for the apoenzyme and the fact that it is more easily removed than P-Pxy-Glu are explicable.

Evaluation of the IFCC-recommended procedure for serum aspartate aminotransferase as modified for use with the centrifugal analyzer.

1981 ◽  
Vol 27 (1) ◽  
pp. 156-159 ◽  
Author(s):  
D E Bruns ◽  
J Savory ◽  
A C Titheradge ◽  
R E Cross ◽  
M R Wills
Keyword(s):  
Cardiac Disease ◽  
Aspartate Aminotransferase ◽  
Present Method ◽  
Pyridoxal Phosphate ◽  
Extensive Evaluation ◽  
Serum Aspartate Aminotransferase

Abstract The IFCC-recommended procedure for aspartate aminotransferase (EC 2.6.1.1) was adapted to the centrifugal analyzer and evaluated during five years. The main hindrance to widespread use of the recommended method is the need for pre-incubation with pyridoxal phosphate. The present method includes a 10-min pre-incubation with pyridoxal phosphate. Extensive evaluation of the method with and without this pre-incubation confirms earlier reports that it eliminates some significant errors, especially for samples from patients with cardiac disease. However, the pre-incubation can be briefer than the recommended 10 min and still provide acceptable results.

scholarly journals Effect of pH, ionic strength and univalent inorganic ions on the reconstitution of aspartate aminotransferase

1974 ◽  
Vol 137 (2) ◽  
pp. 199-203 ◽  
Author(s):  
Liliana Gianfreda ◽  
Gennaro Marino ◽  
Rosaria Palescandolo ◽  
Vincenzo Scardi
Keyword(s):  
Ionic Strength ◽  
Aspartate Aminotransferase ◽  
Pyridoxal Phosphate ◽  
Water Structure ◽  
Inorganic Ions ◽  
Halide Ions ◽  
Ph Change ◽  
Effect Of Ph ◽  
Ph Range ◽  
Ph Curve

1. The effect of pH change on the reconstitution of aspartate aminotransferase (EC 2.6.1.1), i.e. the reactivation of the apoenzyme with coenzyme (pyridoxal phosphate and pyridoxamine phosphate), was studied in the pH range 4.2–8.9 by using three buffer systems at concentrations ranging from 0.025 to 0.1m. 2. Although the profile of the reconstitution rate–pH curve in the range pH5.2–6.8 (covered by sodium cacodylate–HCl buffer) reflects the influence of the H+ concentration on the reconstitution process, the profile of the curve in the pH ranges 4.2–5.6 and 7.2–8.25 (covered respectively by sodium acetate–acetic acid and Tris–HCl buffers) appears to be influenced by the ionic strength of the buffer. 3. The reconstitution is also influenced by univalent inorganic ions such as halide ions and, to a lesser extent, alkali metal ions, which are known to alter the water structure.

scholarly journals Low serum albumin, aspartate aminotransferase, and body mass are risk factors for frailty in elderly people with diabetes – a cross-sectional study

2020 ◽  
Author(s):  
Toshihiko Yanase ◽  
Ikumi Yanagita ◽  
Yuya Fujihara ◽  
Chikayo Iwaya ◽  
Yuichi Kitajima ◽  
...  
Keyword(s):  
Risk Factors ◽  
Regression Analysis ◽  
Serum Albumin ◽  
Body Mass ◽  
Aspartate Aminotransferase ◽  
Cross Sectional Study ◽  
Sectional Study ◽  
Cross Sectional ◽  
Physical Scale ◽  
Independent Risk Factors

Abstract Background: Relatively low dehydroepiandrosterone sulfate (DHEA-S) and high cortisol/DHEA ratio have been suggested to be associated with frailty as evaluated using a physical scale. However, the significance of these two hormones for frailty in elderly patients with type 2 diabetes mellitus (T2DM) has not been assessed using a wider range of measures of frailty, including physical, mental, and social indices.Methods: We performed a cross-sectional study to investigate the significance of these two hormones for frailty in elderly T2DM patients (n=148; ≥65 years), using a broad assessment, the clinical frailty scale, and to reevaluate the risk factors for frailty in elderly T2DM patients. We compared parameters between the non-frail and frail groups using the unpaired t and Mann-Whitney U tests. The Jonckheere-Therpstra test was used to identify relationships with the severity of frailty and risk factors were identified using binary regression analysis.Results: Simple regression analysis identified a number of significant risk factors for frailty, including DHEAS <70 µg/dL and cortisol/DHEA-S ratio ≥0.2. Multiple regression analysis showed that low albumin (<4.0 g/dl) (odds ratio [OR]=5.79, p<0.001), low aspartate aminotransferase (AST) activity (<25 IU/L) (OR=4.34, p=0.009), and low body mass (BM) (<53 kg) (OR=3.85, p=0.012) were independent risk factors for frailty. A significant decrease in DHEA-S and a significant increase in the cortisol/DHEA-S ratio occurred alongside increases in the severity of frailty. DHEA-S concentration positively correlated with both serum albumin and BM.Conclusions: Hypoalbuminemia, low AST, and low BM are independent risk factors for frailty in elderly T2DM patients, strongly implying relative malnutrition in these frail patients. DHEA-S may be important for the maintenance of liver function and BM. A decrease in DHEA-S and an increase in the cortisol/DHEAS ratio may be involved in the mechanism of the effect of malnutrition in elderly T2DM patients. trial registration number: UMIN (number 000031357)

Effects of Buffers on Aspartate Aminotransferase Activity and Association of the Enzyme with Pyridoxal Phosphate

1975 ◽  
Vol 21 (11) ◽  
pp. 1585-1591 ◽  
Author(s):  
Robert Rej ◽  
Raymond E Vanderlinde
Keyword(s):  
Schiff Base ◽  
Aspartate Aminotransferase ◽  
Phosphate Buffer ◽  
Pyridoxal Phosphate ◽  
Human Origin ◽  
Aminotransferase Activity ◽  
Factors Influencing ◽  
Absorbance Spectra ◽  
Stimulation Of

Abstract Using purified enzymes of human origin and patients’ sera, we examined factors influencing the in vitro association of pyridoxal phosphate with aspartate aminotransferase (EC 2.6.1.1). The rate of association was markedly retarded by phosphate buffer in comparison with tris(hydroxymethyl)aminomethane or six other buffers. Pyridoxal phosphate at an incubation concentration of 130 µmol/liter reactivated the entire apoenzyme portion of an apoenzyme/holoenzyme mixture within 5 min in tris(hydroxymethyl)aminomethane; in contrast, less than 20% was associated during 15 min in phosphate. Activity measured in tris(hydroxymethyl)aminomethane-buffer without exogenous pyridoxal phosphate was 4% greater than that in phosphate and was slightly increased by increasing the pH of the assay mixture from 7.5 to 8.0. Aspartate in the incubation medium did not retard the stimulation in tris(hydroxymethyl)aminomethane buffer. While the magnitude of stimulation varied greatly among sera, a consistent mean stimulation of 30% for groups of sera with normal activities was found when asparate at 125 mmol/liter, 2-oxoglutarate at 6.7 mmol/liter and tris(hydroxymethyl)aminomethane at 90 mmol/liter were used, an increase over the 16% with phosphate buffer [Clin. Chem. 19, 92 (1973)]. Absorbance spectra suggest pyridoxal phosphate exists as the Schiff base of tris(hydroxymethyl)aminomethane or aspartate, or both, under conditions of assay incubation (without addition of 2-oxoglutarate). Nonenzymatic catalysis of the reaction by pyridoxal phosphate alone or a formation of a protein/pyridoxal phosphate adduct was discounted with use of D-asparate substrates

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