Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 125
Filter
1.
RSC Adv ; 14(35): 25130-25148, 2024 Aug 12.
Article in English | MEDLINE | ID: mdl-39139248

ABSTRACT

Polyethylene microplastics (PE MPs) have sparked widespread concern about their possible health implications because of their abundance, pervasiveness in the environment and in our daily life. Multiple investigations have shown that a high dosage of PE MPs may adversely impact gastrointestinal health. In tandem with the rising prevalence of Inflammatory bowel disease (IBD) in recent decades, global plastic manufacturing has risen to more than 300 million tons per year, resulting in a build-up of plastic by-products such as PE MPs in our surroundings. We have explored current advancements in the effect PE MPs on IBD in this review. Furthermore, we compared and summarized the detrimental roles of PE MPs in gut microbiota of different organisms viz., earthworms, super worm's larvae, yellow mealworms, brine shrimp, spring tails, tilapia, gilt-head bream, crucian carp, zebrafish, juvenile yellow perch, European sea bass, c57BL/6 mice and human. According to this review, PE MPs played a significant role in decreasing the diversity of gut microbiota of above-mentioned species which leads to the development of IBD and causes severe intestinal inflammation. Finally, we pinpoint significant scientific gaps, such as the movement of such hazardous PE MPs and the accompanying microbial ecosystems and propose prospective research directions.

3.
Plants (Basel) ; 11(19)2022 Sep 27.
Article in English | MEDLINE | ID: mdl-36235403

ABSTRACT

Genome- or gene-editing (abbreviated here as 'GEd') presents great opportunities for crop improvement. This is especially so for the countries in the Asia-Pacific region, which is home to more than half of the world's growing population. A brief description of the science of gene-editing is provided with examples of GEd products. For the benefits of GEd technologies to be realized, international policy and regulatory environments must be clarified, otherwise non-tariff trade barriers will result. The status of regulations that relate to GEd crop products in Asian countries and Australasia are described, together with relevant definitions and responsible regulatory bodies. The regulatory landscape is changing rapidly: in some countries, the regulations are clear, in others they are developing, and some countries have yet to develop appropriate policies. There is clearly a need for the harmonization or alignment of GEd regulations in the region: this will promote the path-to-market and enable the benefits of GEd technologies to reach the end-users.

4.
Hum Cell ; 35(6): 1633-1639, 2022 Nov.
Article in English | MEDLINE | ID: mdl-36068397

ABSTRACT

Endothelial dysfunction is one of the key cornerstone complications of emerging and re-emerging viruses which lead to vascular leakage and a high mortality rate. The mechanism that regulates the origin of endothelial dysregulation is not completely elucidated. Currently, there are no potential pharmacological treatments and curable management for such diseases. In this sense, mesenchymal stromal/stem cells (MSCs) has been emerging to be a promising therapeutic strategy in restoring endothelial barrier function in various lung disease, including ALI and ARDS. The mechanism of the role of MSCs in restoring endothelial integrity among single-strand RNA (ssRNA) viruses that target endothelial cells remains elusive. Thus, we have discussed the therapeutic role of MSCs in restoring vascular integrity by (i) inhibiting the metalloprotease activity thereby preventing the cleavage of tight junction proteins, which are essential for maintaining membrane integrity (ii) possessing antioxidant properties which neutralize the excessive ROS production due to virus infection and its associated hyper host immune response (iii) modulating micro RNAs that regulate the endothelial activation and its integrity by downregulating the inflammatory response during ssRNA infection.


Subject(s)
Mesenchymal Stem Cell Transplantation , Mesenchymal Stem Cells , Virus Diseases , Antioxidants/metabolism , Endothelial Cells/metabolism , Humans , Mesenchymal Stem Cells/physiology , Metalloproteases/metabolism , RNA , Reactive Oxygen Species/metabolism , Tight Junction Proteins/metabolism , Virus Diseases/metabolism
5.
Biochimie ; 201: 139-147, 2022 Oct.
Article in English | MEDLINE | ID: mdl-35724946

ABSTRACT

SARS-CoV-2 uses membrane bound Angiotensin-Converting Enzyme 2 (ACE2) as a key host receptor for its entry. However, inconsistent results are available in terms of shedding of membrane ACE2 and circulating levels of soluble ACE2 during SARS-CoV-2. To ascertain soluble ACE2 as an effective biomarker for the prediction of COVID-19 outcome, in the present study, we investigated the levels of plasma ACE2 during the early phase of infection in COVID-19 patients. The study involved a total of 42 COVID-19 patients along with 10 healthy controls. Plasma levels of ACE2 was determined using ELISA at the time of admission and on day 7 post admission. The association of sACE2 with D-dimer a marker for hyper-coagulation was performed using a dependence test. Compared to healthy controls, SARS-CoV-2 cases has shown a huge increase in the sACE2 at the time of admission. During the course of infection, we found a significant increase (P ≤ 0.001) in sACE2 in severe cases compared to moderate. There was a strong increase in sACE2 in cases with hypertension and diabetes mellitus. Interestingly, a strong positive correlation (P ≤ 0.001) was obtained between sACE2 and D-dimer. Thus, an excessive shedding of ACE2 during the early phase is a common phenomenon in severe form of the SARS-CoV-2. Along with D-dimer, the sACE2 levels could serve as a clinical biomarker for the prediction of disease outcome. However further studies are needed to ascertain its role in host-virus interplay.


Subject(s)
Angiotensin-Converting Enzyme 2 , COVID-19 , Biomarkers , Humans , Peptidyl-Dipeptidase A/metabolism , SARS-CoV-2 , Severity of Illness Index
6.
Microb Pathog ; 158: 105057, 2021 Sep.
Article in English | MEDLINE | ID: mdl-34153419

ABSTRACT

The current pandemic due to the fast spreading of SARS-CoV-2 infection has caused severe impairment in health, social, economic, scientific, and medical sectors across the globe. Owing to the not so well understood mechanism of disease pathogenesis in terms of variations in immune responses, there remains obscure why some of the patients who are infected by the novel SARS-CoV-2 develop an unpredictable clinical course that rapidly causes severe and deadly complications/manifestations. Currently, several assays are available for the confirmation of SARS-CoV-2 infection at the point of care. However, none of these assays can predict the severity of the COVID-19 disease. Thus, the identification of a prognostic biomarker that forecasts the condition of SARS-CoV-2 patients to develop a severe form of the disease could enable the clinicians for more efficient patient triage and treatment. In this regard, the present review describes the role of selected biomolecules that are crucially involved in the immune-pathogenesis of SARS-CoV-2 infection such as hyper-immune responsiveness, bradykinin storm and vascular leakage assuming these may serve as an effective prognostic biomarker in COVID-19 to understand the outcome of the disease. Based on the review, we also propose the development of a cost-effective SERS-based prognostic biosensor for the detection and quantification of biomolecules for use as a point-of-care system during a disease outbreak.


Subject(s)
COVID-19 , SARS-CoV-2 , Biomarkers , Humans , Pandemics
7.
Front Public Health ; 9: 673536, 2021.
Article in English | MEDLINE | ID: mdl-34178928

ABSTRACT

The key challenges to any health care setup during emergency situations, such as that of the COVID-19 pandemic would be to rapidly address hospital preparedness and response tailored to the local population, societal influences, political factors within the existing infrastructure, and workforce. Second, to adopt and moderate policies, standard operating procedures (SOPs) and guidelines issued by national and international agencies, such as WHO, CDC, and the Indian Council for Medical Research (ICMR) were tailor-made to the local conditions of the hospital and community. In this publication, we have discussed the challenges and experiences in preparation and responses to the ongoing COVID-19 pandemic at a tertiary teaching hospital situated at a suburban locale in a small union territory. Puducherry is located in the South Eastern Coromandel Coast of India. The core processes, such as hospital preparedness, adoption, and amendments to SOPs based on dynamic changes in guidelines released by the central and local government, training given to health care workers, setting up the in-house diagnostic facility, surge capacity, management of supplies during the lockdown, infection prevention, and control and patient care are discussed. We have also reinforced our experiences in translating COVID-related opportunities for research and innovation in the form of awards and research proposals for the faculty and students of our institute. The lessons learned in terms of strength and limitations on the ground level of public health during this process is worth sharing as it would provide guidance in preparing the health care setups for pre- and post-pandemic.


Subject(s)
COVID-19 , Pandemics , Communicable Disease Control , Hospitals, Teaching , Humans , India/epidemiology , SARS-CoV-2 , Tertiary Healthcare
8.
J Biol Regul Homeost Agents ; 31(1): 77-80, 2017.
Article in English | MEDLINE | ID: mdl-28337873

ABSTRACT

Cyclosporine-A induces gingival overgrowth with disturbance in the homeostasis of cells and connective tissue proteins. Human gingival fibroblasts were cultured with cyclosporine A, and the expression of two vital endoplasmic stress markers and two prime matrix proteins (connective tissue growth factor (CTGF and periostin) were assessed by RT-PCR. We found that expression of Glucose-Regulated Protein 78 (GRP78/BIP) and CCAAT/enhancer binding protein, C/EBP homologous protein (CHOP) were significantly increased, along with CTGF and periostin, suggesting a role for these factors in gingival overgrowth.


Subject(s)
Cell Adhesion Molecules/genetics , Connective Tissue Growth Factor/genetics , Cyclosporine/adverse effects , Endoplasmic Reticulum Stress/drug effects , Heat-Shock Proteins/genetics , Immunosuppressive Agents/adverse effects , Transcription Factor CHOP/genetics , Biomarkers/metabolism , Cell Adhesion Molecules/agonists , Cell Adhesion Molecules/metabolism , Connective Tissue Growth Factor/agonists , Connective Tissue Growth Factor/metabolism , Endoplasmic Reticulum/drug effects , Endoplasmic Reticulum/metabolism , Endoplasmic Reticulum Chaperone BiP , Endoplasmic Reticulum Stress/genetics , Fibroblasts/cytology , Fibroblasts/drug effects , Fibroblasts/metabolism , Gene Expression Regulation , Gingiva/cytology , Gingiva/drug effects , Gingiva/metabolism , Heat-Shock Proteins/agonists , Heat-Shock Proteins/metabolism , Humans , Primary Cell Culture , Signal Transduction , Transcription Factor CHOP/agonists , Transcription Factor CHOP/metabolism
9.
Br J Cancer ; 116(2): 227-236, 2017 Jan 17.
Article in English | MEDLINE | ID: mdl-28006818

ABSTRACT

BACKGROUND: Recent evidence suggests that bone-related parameters are the main prognostic factors for overall survival in advanced prostate cancer (PCa), with elevated circulating levels of alkaline phosphatase (ALP) thought to reflect the dysregulated bone formation accompanying distant metastases. We have identified that PCa cells express ALPL, the gene that encodes for tissue nonspecific ALP, and hypothesised that tumour-derived ALPL may contribute to disease progression. METHODS: Functional effects of ALPL inhibition were investigated in metastatic PCa cell lines. ALPL gene expression was analysed from published PCa data sets, and correlated with disease-free survival and metastasis. RESULTS: ALPL expression was increased in PCa cells from metastatic sites. A reduction in tumour-derived ALPL expression or ALP activity increased cell death, mesenchymal-to-epithelial transition and reduced migration. Alkaline phosphatase activity was decreased by the EMT repressor Snail. In men with PCa, tumour-derived ALPL correlated with EMT markers, and high ALPL expression was associated with a significant reduction in disease-free survival. CONCLUSIONS: Our studies reveal the function of tumour-derived ALPL in regulating cell death and epithelial plasticity, and demonstrate a strong association between ALPL expression in PCa cells and metastasis or disease-free survival, thus identifying tumour-derived ALPL as a major contributor to the pathogenesis of PCa progression.


Subject(s)
Alkaline Phosphatase/physiology , Cell Proliferation/genetics , Epithelial-Mesenchymal Transition/genetics , Prostatic Neoplasms/pathology , Prostatic Neoplasms/therapy , Alkaline Phosphatase/genetics , Animals , Cell Death/genetics , Cell Movement/genetics , Cells, Cultured , Disease Progression , Disease-Free Survival , HEK293 Cells , Humans , Male , Mice , Neoplasm Metastasis , Prostatic Neoplasms/genetics
10.
Gynecol Oncol Rep ; 12: 52-4, 2015 Apr.
Article in English | MEDLINE | ID: mdl-26076159

ABSTRACT

•We report a rare case of solitary fibrous tumor of vulva.•The lesion is usually benign.•Needs workup for malignant features and other close differentials.•Early aggressive resection ensuring clear margins is recommended.•Tendency for recurrence warrants long term follow-up.

11.
Tsitol Genet ; 49(6): 50-60, 2015.
Article in English | MEDLINE | ID: mdl-26841494

ABSTRACT

Karyomorphological studies have been carried out in nine species and five varieties of the genus Cucumis representing Indian gene pool. The present investigations reveal the occurrence of two somatic chromosome numbers 2n = 14, 24 in the genus. C. ritchiei and C. indicus the two new species, were found to be having somatic chromosome numbers of 2n = 24 and 2n = 20 respectively. The wild species viz. C. hystrix, C. setosus, C. prophetarum, C. dipsaceus, C. indicus have very less number of median-centromeric chromosomes, high asymmetry indices, while melon groups have intermediate number of median -centromeric chromosomes. C. sativus, C. callosus, C. ritchiei show lesser number median-cen-tromeric chromosomes and very less asymmetry indices. The importance of karyotypic variation with respect to speciation within the genus Cucumis have been discussed.


Subject(s)
Chromosome Structures , Chromosomes, Plant/genetics , Cucumis/genetics , Chromosome Mapping , Chromosomes, Plant/diagnostic imaging , Cucumis/cytology , Cucumis/growth & development , India , Karyotyping , Species Specificity , Ultrasonography
12.
Nat Commun ; 5: 3756, 2014 Apr 29.
Article in English | MEDLINE | ID: mdl-24777035

ABSTRACT

Bladder cancers are a leading cause of death from malignancy. Molecular markers might predict disease progression and behaviour more accurately than the available prognostic factors. Here we use whole-genome sequencing to identify somatic mutations and chromosomal changes in 14 bladder cancers of different grades and stages. As well as detecting the known bladder cancer driver mutations, we report the identification of recurrent protein-inactivating mutations in CDKN1A and FAT1. The former are not mutually exclusive with TP53 mutations or MDM2 amplification, showing that CDKN1A dysfunction is not simply an alternative mechanism for p53 pathway inactivation. We find strong positive associations between higher tumour stage/grade and greater clonal diversity, the number of somatic mutations and the burden of copy number changes. In principle, the identification of sub-clones with greater diversity and/or mutation burden within early-stage or low-grade tumours could identify lesions with a high risk of invasive progression.


Subject(s)
Cadherins/genetics , Cyclin-Dependent Kinase Inhibitor p21/genetics , Genetic Variation , Genome/genetics , Urinary Bladder Neoplasms/genetics , Base Sequence , Humans , Molecular Sequence Data , Mutation/genetics , Neoplasm Grading , Sequence Analysis, DNA
13.
J Postgrad Med ; 57(1): 9-15, 2011.
Article in English | MEDLINE | ID: mdl-21206128

ABSTRACT

BACKGROUND: Cardiovascular diseases are one of the leading causes of death in India. There is high prevalence of cardiovascular risk factors in urban Tamil Nadu. There are limited data on the prevalence of behavioral risk factors and overweight in rural Tamil Nadu. AIM: We estimated prevalence of behavioral risk factors, overweight and central obesity in a rural population in Tamil Nadu, India. SETTING AND DESIGN: We conducted a cross-sectional survey in 11 villages in Kancheepuram/Thiruvallur districts, Tamil Nadu. MATERIALS AND METHODS: Study population included 10,500 subjects aged 25-64 years. We collected data on behavioral risk factors and anthropometric measurements. Body mass index (BMI) was categorized using the classification recommended for Asians. Central obesity was defined as waist circumference ≥90 cm for men and ≥80 cm for women. We computed proportions for all risk factors and used trend chi-square to examine trend. RESULTS: Among the 10,500 subjects, 4927 (47%) were males. Among males, 1852 (37.6%) were current smokers and 3073 (62.4%) were current alcohol users. Among females, 840 (15.1%) were smokeless tobacco users. BMI was ≥23.0 kg/m 2 for 1618 (32.8%) males and 2126 (38.2%) females. 867 (17.6%) males and 1323 (23.7%) females were centrally obese. Most commonly used edible oil was palm oil followed by sunflower oil and groundnut oil. CONCLUSION: We observed high prevalence of tobacco use, alcohol use and central obesity in the rural population in Tamil Nadu. There is need for health promotion programs to encourage adoption of healthy lifestyle and policy interventions to create enabling environment.


Subject(s)
Alcoholism/epidemiology , Overweight/epidemiology , Tobacco Use Disorder/epidemiology , Adult , Age Distribution , Body Mass Index , Cardiovascular Diseases/epidemiology , Cross-Sectional Studies , Female , Humans , India/epidemiology , Life Style , Male , Middle Aged , Prevalence , Risk Factors , Rural Population/statistics & numerical data , Sex Distribution , Smoking/adverse effects , Smoking/epidemiology
14.
Indian J Exp Biol ; 47(2): 140-6, 2009 Feb.
Article in English | MEDLINE | ID: mdl-19374170

ABSTRACT

A protocol has been devised for enhanced in vitro regeneration of critically endangered Mantisia spathulata Schult. and Mantisia wengeri Fischer. Highest Bud Forming Capacity (BFC) of 6.10 +/- 0.55 with an average of 19.93 +/- 3.19 roots was obtained for M. spathulata within 5-6 weeks in Murashige and Skoogs (MS) medium supplemented with a combination of 10.0 microM of N6-benzyladenine (BA) and 2.5 microM of alpha-naphtalene acetic acid (NAA). For M. wengeri, BFC of 7.82 +/- 0.73 and 20.86 +/- 1.65 roots was achieved in MS media supplemented with a combination of 5.0 microM BA and 2.5 microM of NAA RAPD markers were used to evaluate the genetic stability of in vitro raised hardened plantlets. Similarity coefficient among the regenerated plants ranged between 0.85-0.98 for M. spathulata and 0.83-0.98 for M. wengeri. Maximum of 88 and 90% genetic similarity were obtained between in vitro raised hardened plantlets and mother stock of M. spathulata and M. wengeri, respectively through RAPD analysis. The hardened plantlets after RAPD analysis on being transferred to soil of experimental garden showed no marked phenotypic variations in vegetative or floral characteristics.


Subject(s)
Agriculture/methods , Random Amplified Polymorphic DNA Technique/methods , Regeneration , Rhizome/physiology , Zingiberaceae/physiology , DNA, Plant/analysis , Gene Expression Regulation, Plant , Genetic Markers , Rhizome/anatomy & histology , Zingiberaceae/anatomy & histology
15.
Genet Mol Res ; 5(4): 816-27, 2006 Dec 12.
Article in English | MEDLINE | ID: mdl-17183489

ABSTRACT

In order to survive at high temperatures, thermophilic prokaryotes (Archaea and Eubacteria) adopt different strategies. Among several important contributing factors for stability of proteins are CG-rich codons, the ratio of charged amino acids compared to uncharged amino acids, ionic interactions, amino acid preferences and their distribution, post-translational modifications, and solute accumulation. However, these factors may differ from taxon to taxon, both within and between species depending upon the composition of proteins found in these organisms. This is exemplified in the case of differences in strategies adopted by soluble proteins and membrane proteins. Therefore, it appears that no single factor or combination of factors together can be universally attributed to the provision of thermal stability in proteins.


Subject(s)
Archaea/metabolism , Archaeal Proteins/metabolism , Bacteria/metabolism , Bacterial Proteins/metabolism , Hot Temperature , Thermodynamics , Adaptation, Biological , Amino Acids/metabolism , Archaea/genetics , Bacteria/genetics , Structure-Activity Relationship
16.
Waste Manag ; 26(5): 504-8, 2006.
Article in English | MEDLINE | ID: mdl-15975784

ABSTRACT

Resource recovery from two metallurgical residues by flotation was investigated applying an electrostatic model to select initial conditions. The first, a sulphation roast/water leach residue, was processed to float lead sulphate, comparing dodecylamine and xanthate collectors. From the second, a neutralization residue, gypsum, was recovered by reverse flotation of ferric hydroxide, comparing oleate and sulphonate collectors. In both cases, further upgrading by acid leaching was considered.


Subject(s)
Calcium Sulfate/isolation & purification , Industrial Waste , Lead/isolation & purification , Models, Theoretical , Refuse Disposal/methods , Amines/chemistry , Calcium/analysis , Calcium Sulfate/chemistry , Ferric Compounds/chemistry , Iron/analysis , Lead/analysis , Lead/chemistry , Metallurgy , Static Electricity , Sulfuric Acids/chemistry , Zinc/analysis
17.
Genet. mol. res. (Online) ; 5(4): 816-827, 2006.
Article in English | LILACS | ID: lil-482077

ABSTRACT

In order to survive at high temperatures, thermophilic prokaryotes (Archaea and Eubacteria) adopt different strategies. Among several important contributing factors for stability of proteins are CG-rich codons, the ratio of charged amino acids compared to uncharged amino acids, ionic interactions, amino acid preferences and their distribution, post-translational modifications, and solute accumulation. However, these factors may differ from taxon to taxon, both within and between species depending upon the composition of proteins found in these organisms. This is exemplified in the case of differences in strategies adopted by soluble proteins and membrane proteins. Therefore, it appears that no single factor or combination of factors together can be universally attributed to the provision of thermal stability in proteins.


Subject(s)
Archaea/metabolism , Bacteria/metabolism , Hot Temperature , Archaeal Proteins/metabolism , Bacterial Proteins/metabolism , Thermodynamics , Adaptation, Biological , Amino Acids/metabolism , Archaea/genetics , Bacteria/genetics , Structure-Activity Relationship
18.
Asian J Surg ; 25(4): 319-24, 2002 Oct.
Article in English | MEDLINE | ID: mdl-12471006

ABSTRACT

OBJECTIVES: In recent years, well-differentiated carcinomas of the thyroid have been stratified into low-risk and high-risk groups. The pattern of thyroid cancer in India is different from that seen in the West. Moreover, patients present with more advanced stages of the disease. Our aim was to develop protocols for the management of well-differentiated thyroid cancer, based on the analysis of our data and our experience. METHODS: Cases of thyroid carcinoma, which were surgically treated at the Tata Memorial Hospital during 1970-5, were studied. The survival curves were plotted according to the Kaplan-Meier method. Univariate analysis was done using the log rank test. The prognostic factors analyzed were age, sex, tumour size, extra-thyroid extension, distant metastases and lymph node metastases. Multivariate analysis using the Cox regression model was performed. Analyses were separate for follicular and papillary carcinomas. RESULTS: Four hundred and seventeen cases were entered in the study, of which 198 were follicular and 219 were papillary. Based on the evidence derived from this study, we stratified our cases into low- and high-risk groups. The low-risk group consisted of patients below 40 years of age, nodules smaller than 5 cm, absence of extra-thyroidal spread and absence of distant metastases. For follicular carcinoma, the low-risk group had 100% survival at 15 years, compared with 40% for the high-risk group. (p < 0.001). For papillary carcinomas, the survival at 15 years was 95% for the low-risk group and 40% for the high-risk group (p < 0.001). CONCLUSIONS: We recommend lobectomy for the low-risk group, and total thyroidectomy for the high-risk group and for cases with lymph node metastases. In the latter, total thyroidectomy facilitates the use of 131I.


Subject(s)
Adenocarcinoma, Follicular/surgery , Carcinoma, Papillary/surgery , Evidence-Based Medicine , Thyroid Neoplasms/surgery , Adenocarcinoma, Follicular/mortality , Carcinoma, Papillary/mortality , Humans , India/epidemiology , Lymphatic Metastasis , Neoplasm Recurrence, Local , Proportional Hazards Models , Survival Analysis , Thyroid Neoplasms/mortality
19.
Biotechnol Adv ; 20(2): 101-53, 2002 May.
Article in English | MEDLINE | ID: mdl-14538059

ABSTRACT

This review deals with the production of high-value secondary metabolites including pharmaceuticals and food additives through plant cell cultures, shoot cultures, root cultures and transgenic roots obtained through biotechnological means. Plant cell and transgenic hairy root cultures are promising potential alternative sources for the production of high-value secondary metabolites of industrial importance. Recent developments in transgenic research have opened up the possibility of the metabolic engineering of biosynthetic pathways to produce high-value secondary metabolites. The production of the pungent food additive capsaicin, the natural colour anthocyanin and the natural flavour vanillin is described in detail.

20.
Indian J Biochem Biophys ; 39(1): 55-9, 2002 Feb.
Article in English | MEDLINE | ID: mdl-22896889

ABSTRACT

Maize malic enzyme was rapidly inactivated by micromolar concentrations of cupric nitrate in the presence of ascorbate at pH, 5.0. Ascorbate or Cu2+ alone had no effect on enzyme activity. The substrate L-malate or NADP individually provided almost total protection against Cu2+-ascorbate inactivation. The loss of enzyme activity was accompanied by cleavage of the enzyme. The cleaved peptides showed molecular mass of 55 kDa, 48 kDa, 38 kDa, and 14 kDa. Addition of EDTA, histidine and imidazole provided protection. The results of protection experiments with sodium azide, DABCO and catalase suggested that reactive oxygen species were generated resulting in loss of enzyme activity. This was further supported by experiments showing that the rate of enzyme inactivation was higher in D2O than in water. It is suggested that maize malic enzyme is modified by reactive oxygen species like singlet oxygen and H2O2 generated by Cu2+-ascorbate system and the modified amino acid residue(s) may be located at or near the substrate-binding site of the enzyme.


Subject(s)
Ascorbic Acid/chemistry , Copper/chemistry , Malates/chemistry , NADP/chemistry , Zea mays/metabolism , Amino Acids/chemistry , Catalase/chemistry , Deuterium Oxide/chemistry , Edetic Acid/chemistry , Histidine/chemistry , Hydrogen Peroxide/chemistry , Hydrogen-Ion Concentration , Imidazoles/chemistry , Oxygen/chemistry , Piperazines/chemistry , Reactive Oxygen Species
SELECTION OF CITATIONS
SEARCH DETAIL