Browsing by Author "Veena Taneja"

Now showing 1 - 7 of 7

A histidine thiol 100 kDa, tetrameric acid phosphatase from lentil, Lens esculenta, seeds with the characteristics of protein tyrosine phosphatases
(Elsevier, 1999) Sadroddin Mohammadi Roknabadi; Sudeep Kumar Bose; Veena Taneja
A non-specific acid phosphatase (APase) hydrolysing L-tyrosine-O-phosphate and 3'-AMP was purified to electrophoretic homogeneity from mature lentil seeds with apparent native molecular mass of 100 kDa and subunit molecular mass of 24 kDa. These activities appear to reside on the same protein which shows a single band in native and SDS-PAGE. The pH optimum is 5.5, while the K(m) (mM) and V(max) (μmoles/min/mg protein) for p-nitrophenyl phosphate (pNPP) are 0.7 and 9.2 and for L-tyrosine-O-phosphate 1.4 and 10.1, respectively, at 30°C and for 3'-AMP, 2 and 4.4 at 37°C. The protein also hydrolyses other phosphomonoesters to a lesser extent. L-Tyrosine-O-phosphate, 3'-AMP and pNPP hydrolysis is potently inhibited by micromolar orthovanadate and also to nearly the same extent by sodium fluoride, potassium tartrate and metal ions. Histidine and cysteine are likely to be involved in the catalysis. Thermal inactivation studies indicate that the active site conformations for pNPP and 3'-AMP hydrolytic activities are different. The enzyme shows the characteristics of the animal protein tyrosine phosphatase. Copyright (C) 1999 Elsevier Science B.V.
Effect of Early Iron Deficiency in Rat on the γ‐Aminobutyric Acid Shunt in Brain
(1986) Veena Taneja; Kamalapati Mishra; K.N. Agarwal
Early iron deficiency in rat does not affect the weight or the protein, DNA, and RNA content but results in a slight reduction in γ‐aminobutyric acid (GABA) (13%, p < 0.01) and glutamic acid (20%, p < 0.001) content of the brain. The activities of the two GABA shunt enzymes, glutamate dehydrogenase and GABA‐transaminase, and of the NAD+‐linked isocitrate dehydrogenase (ICDH) were inhibited whereas the glutamic acid decarboxylase, mitochondrial NADP+‐linked ICDH, and succinic dehydrogenase activities remained unaltered in brain. On rehabilitation with the iron‐supplemented diet for 1 week, these decreased enzyme activities in brain attained the corresponding control values. However, the hepatic nonheme iron content increased to about 80% of the control, after rehabilitation for 2 weeks. A prolonged iron deficiency resulting in decreased levels of glutamate and GABA may lead to endocrinological, neurological, and behavioral alterations. Copyright © 1986, Wiley Blackwell. All rights reserved
Induction of a germination specific, low molecular weight, acid phosphatase isozyme with specific phosphotyrosine phosphatase activity in lentil (Lens esculenta) seeds
(Academic Press Inc., 1998) Sudeep Kumar Bose; Veena Taneja
A germination specific isozyme of acid phosphatase (EC 3.1.3.2) hydrolysing O-phospho-L-Tyrosine, pH optima 5.5 is induced in lentil seeds. When seeds at 0 h, 24 h and 36 h of germination are electrophorezed, native PAGE on specific enzyme staining shows several constitutive isozymes of acid phosphatases. At 48 h, an isozyme is induced which gradually decreases and then disappears at 108 h of germination. The short lived, induced isozyme is present in the embryo and seed-coat but not in the plumule and the radical. Induction of this isozyme is inhibited by cycloheximide and actinomycin-D and increased by plant growth regulators such as heteroauxin and gibbrellic acid treatment during germination. The induced isozyme is a single 30 kD polypeptide, with subunit molecular mass of 25 kD, shows activity for O-phospho-L-Tyrosine. It is strongly inhibited by vanadate (μM), molybdate, tungustate as also by iodoacetate, p-chloromercuribenzoate and diethylpyrocarbonate. This study shows for the first time that the germination induced low molecular weight Acid phosphatase is a Tyrosine phosphatase super family class IV enzyme, having a role in cellular differentiation and development during seed germination.
Papain catalysed hydantoin hydrolysis in the synthesis of amino acids
(Academic Press Inc., 1998) Rekha Rai; Veena Taneja
Papain has been shown, for the first time, to exhibit hydantoinase activity. It hydrolyzes the 5-mono and 5,5@?-disubstituted hydantoins with linear and cyclic substituents, with a higher activity for the latter, to the corresponding N-carbamoyl amino acids, which on chemical hydrolysis yield the corresponding amino acids. The upscaling of this simple procedure could be a major breakthrough for amino acid synthesis in chemical and pharmaceutical industries.
Papain in tue synthesis of natural and novel amino acids
(1997) Rekha Rai; Veena Taneja
[No abstract available]
Protein deprivation and the brain: Effect on enzymes and free amino acids related to glutamate metabolism in rats
(1981) K.N. Agarwal; C. Prasad; Veena Taneja
6-week-old, female albino rats were fed one of three diets containing 5, 10 and 20% casein for a period of 15 days. Rats fed the low protein diet (5 % casein) lost weight (6.3 ± 0.7 g/week), whereas those on the two higher protein diets gained weight. The concentrations of protein and free amino nitrogen in the brain were significantly lower in those on the low protein diet (5% casein) compared to those on the high protein diet (20% casein). The activities of brain enzymes, glutamine synthetase, glutamine transferase, glutaminase I, glutamin-ase II and glutamate decarboxylase, and the concentrations of free amino acids, aspartic acid, glutamic acid, glutamine, alanine and GABA were also lower. The prospect for nutritional rehabilitation of rats fed the low protein diet appeared to be excellent and was illustrated by the reversal of the above changes after 15 days on the high protein diet. The diet containing 10% casein was sufficient for the normal production of enzymes and free amino acids related to glutamate metabolism. © 1981 S. Karger AG, Basel.
Xanthine oxidase in lentil (Lens esculenta) seedlings
(1977) Raj Kumar; Veena Taneja
Until recently there were no reports regarding the presence of xanthine oxidase (xanthine:oxygen oxidoreductase, EC 1.2.3.2) in plants. Direct evidence for its presence in lentil seedlings is reported here. Xanthine oxidase activity increases with the period of germination, reaching a maximum at 24 h and decreasing thereafter. The pH optimum for its activity is at pH 8.0. Almost equal activity is observed against xanthine and hypoxanthine. The Km for xanthine is 1.05 mM, and considerable inhibition is observed at high substrate concentration. © 1977.