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1.
Malar J ; 22(1): 45, 2023 Feb 06.
Artículo en Inglés | MEDLINE | ID: mdl-36747302

RESUMEN

BACKGROUND: Compared to 2017, India achieved a significant reduction in malaria cases in 2020. Madhya Pradesh (MP) is a tribal dominated state of India with history of high malaria burden in some districts. District Mandla of MP state showed a considerable decline in malaria cases between 2000 and 2013, except in 2007. Subsequently, a resurgence of malaria cases was observed during 2014 and 2015. The Malaria Elimination Demonstration Project (MEDP) was launched in 2017 in Mandla with the goal to achieve zero indigenous malaria cases. This project used: (1) active surveillance and case management using T4 (Track fever, Test fever, Treat patient, and Track patient); (2) vector control using indoor residual sprays and long-lasting insecticidal nets; (3) information education communication and behaviour change communication; and (4) regular monitoring and evaluation with an emphasis on operational and management accountability. This study has investigated malaria prevalence trends from 2008 to 2020, and has predicted trends for the next 5 years for Mandla and its bordering districts. METHODS: The malaria prevalence data of the district Mandla for the period of January 2008 to August 2017 was obtained from District Malaria Office (DMO) Mandla and data for the period of September 2017 to December 2020 was taken from MEDP data repository. Further, the malaria prevalence data for the period of January 2008 to December 2020 was collected from DMOs of the neighbouring districts of Mandla. A univariate time series and forecast analysis was performed using seasonal autoregressive integrated moving average model. FINDINGS: Malaria prevalence in Mandla showed a sharp decline [- 87% (95% CI - 90%, - 84%)] from 2017 to 2020. The malaria forecast for Mandla predicts zero cases in the next 5 years (2021-2025), provided current interventions are sustained. By contrast, the model has forecasted a risk of resurgence of malaria in other districts in MP (Balaghat, Dindori, Jabalpur, Seoni, and Kawardha) that were not the part of MEDP. CONCLUSION: The interventions deployed as part of MEDP have resulted in a sustainable zero indigenous malaria cases in Mandla. Use of similar strategies in neighbouring and other malaria-endemic districts in India could achieve similar results. However, without adding extra cost to the existing intervention, sincere efforts are needed to sustain these interventions and their impact using accountability framework, data transparency, and programme ownership from state to district level.


Asunto(s)
Malaria , Humanos , Factores de Tiempo , Malaria/epidemiología , Malaria/prevención & control , India/epidemiología , Proyectos de Investigación , Manejo de Caso
2.
Malar J ; 22(1): 62, 2023 Feb 21.
Artículo en Inglés | MEDLINE | ID: mdl-36810077

RESUMEN

BACKGROUND: Global malaria cases rose by 14 million, and deaths by 69,000, in 2020. In India, a 46% decline has been reported between 2020 and 2019. In 2017, the Malaria Elimination Demonstration Project conducted a needs-assessment of the Accredited Social Health Activists (ASHAs) of Mandla district. This survey revealed the inadequate level of knowledge in malaria diagnosis and treatment. Subsequently, a training programme was launched for enhancing malaria-related knowledge of ASHAs. The present study was conducted in 2021 to evaluate the impact of training on malaria-related knowledge and practices of ASHAs in Mandla. This assessment was also done in two adjoining districts: Balaghat and Dindori. METHODS: A cross-sectional survey using a structured questionnaire was administered to ASHAs to measure their knowledge and practices related to malaria etiology, prevention, diagnosis, and treatment. A comparison of information collected from these three districts was performed using simple descriptive statistics, comparison of means and multivariate logistic regression analysis. RESULTS: Significant improvement was noted amongst ASHAs of district Mandla between 2017 (baseline) and 2021 (endline) in knowledge related to malaria transmission, preventive measures, adherence to the national drug policy, diagnosis using rapid diagnostic tests, and identification of age group-specific, colour-coded artemisinin combination therapy blister packs (p < 0.05). The multivariate logistic regression analysis revealed that odds of Mandla baseline was 0.39, 0.48, 0.34, and 0.07 times lower for malaria-related knowledge on disease etiology, prevention, diagnosis, and treatment, respectively (p < 0.001). Further, participants in districts Balaghat and Dindori showed significantly lower odds for knowledge (p < 0.001) and treatment practices (p < 0.01) compared to Mandla endline. Education, attended training, having a malaria learner's guide, and minimum 10 years' work experience were potential predictors for good treatment practices. CONCLUSION: The findings of the study unequivocally establishes significant improvement in overall malaria-related knowledge and practices of ASHAs in Mandla as a result of periodic training and capacity building efforts. The study suggests that learnings from Mandla district could be helpful in improving level of knowledge and practices among frontline health workers.


Asunto(s)
Malaria , Humanos , Estudios Transversales , India , Agentes Comunitarios de Salud , Encuestas y Cuestionarios
3.
Gene ; 114(1): 75-80, 1992 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-1339367

RESUMEN

Candida glabrata harbors multiple genes encoding metallothionein (MT). We have disrupted MT-IIa, an amplified locus, and MT-IIb, a single-copy gene, to determine the roles of various MT genes in CuSO4 resistance in C. glabrata. The concentration of CuSO4 required to inhibit the growth by 50% (IC50) of a C. glabrata strain harboring an amplified MT-IIa locus and a single-copy MT-IIb and MT-I genes was 7 mM in a synthetic complete medium. The IC50 decreased to approx. 1 mM when the amplified MT-IIa locus was deleted. The disruption of the MT-IIb gene decreased the IC50 further to 0.1 mM. The CuSO4 resistance in a strain lacking both of the MT-II genes was attributable to MT-I; no evidence was found for the production of (gamma EC)nG isopeptides. The comparison of the nucleotide sequence of MT-IIb to that of MT-IIa revealed the same coding sequence with differences in the 5' region. However, substantial differences were found in the 3' region. MT-IIb was expressed since we were able to purify the protein from the strain that had an intact MT-IIb gene, but a deleted MT-IIa gene. In addition, CuSO4 resistance was provided by MT-IIb. Northern analysis of the total RNA from varied C. glabrata strains indicated no significant changes in the expression of MT-I in the presence or absence of the MT-II genes.


Asunto(s)
Candida/genética , Cobre/farmacología , Metalotioneína/genética , Secuencia de Aminoácidos , Secuencia de Bases , Northern Blotting , Southern Blotting , Candida/efectos de los fármacos , Sulfato de Cobre , Análisis Mutacional de ADN , Farmacorresistencia Microbiana/genética , Metalotioneína/química , Datos de Secuencia Molecular , Mutagénesis/genética
4.
Gene ; 113(1): 119-24, 1992 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-1563627

RESUMEN

The yeast Candida glabrata harbors two distinct gene families that encode metallothioneins (MTs). One of these loci, the MT-IIa locus, exhibits selective and tandem amplification in many wild type strains of C. glabrata. The present paper demonstrates that the amplified MT-IIa gene contains autonomously replicating sequences (ARS). These ARS elements have been used to construct vectors capable of replicating in C. glabrata. The ARS element(s) in the MT-IIa gene were localized to a 457-bp segment downstream from the MT-IIa coding sequence. Although plasmids containing this fragment transform C. glabrata with high frequency, the stability of the transformants and the copy number of the plasmid improve when the entire 1.25-kb MT-IIa gene is used. Transformation of C. glabrata with plasmids carrying the 2 microns circle ARS of Saccharomyces cerevisiae led to the formation of micro-colonies, indicating that the ARS elements of 2 microns plasmids replicate only to a limited extent in C. glabrata. Conversely, a C. glabrata plasmid carrying three copies of the MT-IIa gene was able to transform S. cerevisiae.


Asunto(s)
Candida/genética , Replicación del ADN/genética , Genes Fúngicos , Metalotioneína/genética , Secuencia de Bases , Clonación Molecular/métodos , Amplificación de Genes , Datos de Secuencia Molecular , Familia de Multigenes , Oligodesoxirribonucleótidos , Plásmidos , Secuencias Repetitivas de Ácidos Nucleicos , Mapeo Restrictivo , Transformación Genética
5.
J Inorg Biochem ; 69(4): 293-303, 1998 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-9654753

RESUMEN

A Candida glabrata cadmium-sensitive mutant partially defective in glutathione production and exhibiting a complete absence of phytochelatins was used to clone a gene required for Cd tolerance. Transformation of the Cd-sensitive mutant with a genomic library from the wild-type C. glabrata led to the cloning of a gene that restored Cd tolerance and formation of Cd-glutathione and Cd-phytochelatin complexes. The cloned gene showed high levels of nucleic acid and protein sequence homology to the HEM2 genes, encoding porphobilinogen synthases, from several sources. It was shown that the C, glabrata Cd-sensitive mutant indeed exhibited a significant reduction in porphobilinogen synthase levels. The cloned C. glabrata gene complemented a hem2 mutant of Saccharomyces cerevisiae and restored porphobilinogen synthase activity in the mutant. The Cd sensitive mutant predictably showed decreased levels of sulfite reductase that requires siroheme, a metabolite produced in the heme biosynthetic pathway. The addition of cysteine, but not methionine, increased glutathione levels and Cd tolerance of both the wild-type and the mutant strain. However, addition of hemin chloride and methionine together restored Cd tolerance indicating that heme was required for transsulfuration of homocysteine to cysteine.


Asunto(s)
Cadmio/farmacología , Candida/efectos de los fármacos , Candida/genética , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Genes Fúngicos , Porfobilinógeno Sintasa/genética , Porfobilinógeno Sintasa/metabolismo , Secuencia de Aminoácidos , Animales , Cadmio/metabolismo , Candida/metabolismo , Clonación Molecular , Farmacorresistencia Microbiana/genética , Prueba de Complementación Genética , Glutatión/metabolismo , Hemo/metabolismo , Humanos , Metaloproteínas/metabolismo , Ratones , Datos de Secuencia Molecular , Mutación , Fitoquelatinas , Proteínas de Plantas/metabolismo , Ratas , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Homología de Secuencia de Aminoácido
6.
J Inorg Biochem ; 61(2): 125-42, 1996 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-8576707

RESUMEN

Phytochelatins (PCs) are glutathione-derived peptides with the general structure (gamma-Glu-Cys)nGly, where n varies from 2 to 11. A variety of metal ions such as Cu(II), Cd(II), Pb(II), Zn(II), and Ag(I) induce PC synthesis in plants and some yeasts. It has generally been assumed that the inducer metals also bind PCs. However, very little information is available on the binding of metals other than Cu(I) and Cd(II) to PCs. In this paper, we describe the Ag(I)-binding characteristics of PCs with the structure (gamma-Glu-Cys)2Gly, (gamma-Glu-Cys)3Gly, and (gamma-Glu-Cys)4Gly. The Ag(I)-binding stoichiometries of these three peptides were determined by (i) UV/VIS spectrophotometry, (ii) luminescence spectroscopy at 77 K, and (iii) reverse-phase HPLC. The three techniques yielded similar results. ApoPCs exhibit featureless absorption in the 220-340 nm range. The binding of Ag(I) to PCs induced the appearance of specific absorption shoulders. The titration end point was indicated by the flattening of the characteristic absorption shoulders. Similarly, luminescence at 77 K due to Ag(I)-thiolate clusters increased with the addition of graded Ag(I) equivalents. The luminescence declined when Ag(I) equivalents in excess of the saturating amounts were added to the peptides. At neutral pH, (gamma-Glu-Cys)2Gly, (gamma-Glu-Cys)3Gly, and (gamma-Glu-Cys)4Gly bind 1.0, 1.5, and 4.0 equivalents of Ag(I), respectively. The Ag(I)-binding capacity of (gamma-Glu-Cys)2Gly and (gamma-Glu-Cys)3Gly was increased at pH 5.0 and below so that Ag(I)/-SH ratio approached 1.0. A similar pH-dependent binding of Ag(I) to glutathione was also observed. The increased Ag(I)-binding to PCs at lower pH is of physiological significance as these peptides accumulate in acidic vacuoles. We also report lifetime data on Ag(I)-PCs. The relatively long decay-times (approximately 0.1-0.3 msec) accompanied with a large Stokes shift in the emission band are indicative of spin-forbidden phosphorescence.


Asunto(s)
Metaloproteínas/química , Metaloproteínas/metabolismo , Proteínas de Plantas/química , Proteínas de Plantas/metabolismo , Plata/metabolismo , Secuencia de Aminoácidos , Cadmio/metabolismo , Candida/metabolismo , Cromatografía Líquida de Alta Presión , Glutatión , Mediciones Luminiscentes , Metaloproteínas/aislamiento & purificación , Datos de Secuencia Molecular , Fitoquelatinas , Proteínas de Plantas/aislamiento & purificación , Unión Proteica , Teoría Cuántica , Schizosaccharomyces/metabolismo , Espectrometría de Fluorescencia
7.
Toxicol Lett ; 6(1): 37-41, 1980 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-7423543

RESUMEN

Following a single i.p. dose of the radioisotope, 203Hg was found to accumulate in both the high and low molecular weight (MW) fractions of the kidney and liver of the frog. The course of 203Hg appearance in the 2 fractions varied in the liver; 203Hg was exclusively associated with the higher MW fractions at 2 days whereas the radiotracer appeared in both low and high MW fractions at 4 and 7 days after administration. In the kidneys, however, 203Hg was associated with high and low MW fractions at all the intervals studied. Low MW 203Hg binding fraction appeared to be a metallothionein-like substance.


Asunto(s)
Riñón/metabolismo , Hígado/metabolismo , Mercurio/metabolismo , Ranidae/metabolismo , Animales , Riñón/análisis , Hígado/análisis , Masculino , Radioisótopos de Mercurio , Metalotioneína/metabolismo
8.
Artículo en Inglés | MEDLINE | ID: mdl-2494321

RESUMEN

Low molecular weight 110mAg-binding proteins have been purified from the goat and rat testis using a combination of acetone fractionation, gel filtration and ion-exchange chromatography. Both the rat and goat 110mAg-binding proteins existed in three isoforms, although the goat isoforms carried higher net negative charge than the corresponding isoforms of the rat. The average molecular weight of the goat isoforms was 8000 daltons, whereas that of the rat isoforms was 6300. The goat 110mAg-binding protein (a mixture of all the isoforms) was stable when heated at 85 degrees C for 15 min. The isoform II of the rat 110mAg-binding protein showed little absorbance at 280 nm, although the corresponding isoform of the goat protein did show significant absorbance at the same wavelength.


Asunto(s)
Proteínas Portadoras/aislamiento & purificación , Plata/metabolismo , Testículo/análisis , Animales , Cromatografía en Gel , Ácido Edético/farmacología , Cabras , Calor , Masculino , Metalotioneína/aislamiento & purificación , Peso Molecular , Ratas
11.
Indian J Tuberc ; 55(4): 188-91, 2008 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-19295105

RESUMEN

OBJECTIVE: To analyse the treatment outcome of Cat I smear positive relapse and failure cases and their fate when treated with Cat II regimen under RNTCP. METHODS: All Cat I smear positive relapse and failure TB patients treated with Category II regimen from 1994 to 2005 in a chest clinic of Delhi were analysed in this retrospective study. The re-treatment outcome data for relapse and failure cases of Cat I when treated with Cat II regimen was reviewed. RESULTS: The study population included 5576 registered as Cat I sputum positive cases in Gulabi Bagh chest clinic from 1994 to 2005. A total of 190 (3.4%) failed on Cat I regimen. Further out of 4905 (87.9%) successfully treated Cat I patients, 442 (9%) presented as relapses. The treatment success rate for relapse and failure cases of Cat I when subsequently treated with Cat II regimen were 76.4% and 48.8% respectively, with a significantly higher failure rate (27.6%) among Cat I failures subsequently treated with Cat II regimen. CONCLUSION: The failure cases of Cat I subsequently treated with Cat II were observed to have a significantly lower success rates (p < 0.05) as compared to relapse cases. The need for reappraisal of Cat II re-treatment regimen for failure cases among Cat I is suggested.


Asunto(s)
Control de Enfermedades Transmisibles/métodos , Control de Enfermedades Transmisibles/estadística & datos numéricos , Tuberculosis/tratamiento farmacológico , Estudios de Seguimiento , Humanos , India , Recurrencia , Inducción de Remisión , Estudios Retrospectivos , Factores de Tiempo , Insuficiencia del Tratamiento , Tuberculosis/clasificación , Tuberculosis/diagnóstico
12.
Biochem J ; 213(2): 459-65, 1983 Aug 01.
Artículo en Inglés | MEDLINE | ID: mdl-6615447

RESUMEN

A sensitive radioimmunoassay for rat liver metallothionein-I has been developed using avid and high-titre antibodies obtained from sheep that were immunized with a conjugate of metallothionein and rabbit immunoglobulin G. The assay was specific for metallothionein-I, and did not depend on the particular metal bound to the protein. There was no significant cross-reaction with rat liver metallothionein-II. The use of the assay to measure metallothionein concentrations in rat plasma and kidneys is described.


Asunto(s)
Riñón/análisis , Hígado/análisis , Metaloproteínas/análisis , Metalotioneína/análisis , Animales , Cadmio/farmacología , Cobre/metabolismo , Cobre/farmacología , Reacciones Cruzadas , Compuestos Ferrosos/farmacología , Metalotioneína/sangre , Radioinmunoensayo/métodos , Ratas , Ratas Endogámicas , Zinc/farmacología
13.
Biochem J ; 219(2): 539-46, 1984 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-6743231

RESUMEN

Large amounts of Cu-metallothionein were obtained by 2-mercaptoethanol and sodium dodecyl sulphate extractions of the particulate fractions of the liver of pigs given high-Cu2+ diets or rats injected with Cu2+. Three isoproteins were purified from pig liver and characterized on the basis of their physicochemical properties, metal content and amino acid composition. No such pool of Cu-metallothionein was present in the liver of Cu2+-loaded sheep or of rats given Cu2+-supplemented diets.


Asunto(s)
Cobre/metabolismo , Hígado/metabolismo , Metalotioneína/metabolismo , Aminoácidos/análisis , Animales , Fraccionamiento Celular , Cromatografía en Gel , Cobre/farmacología , Hígado/efectos de los fármacos , Metalotioneína/aislamiento & purificación , Ratas , Ratas Endogámicas , Ovinos , Especificidad de la Especie , Porcinos
14.
Biochem J ; 217(3): 859-62, 1984 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-6712602

RESUMEN

The concentrations of metallothionein-I in the plasma and liver of neonatal rats were measured by radioimmunoassay. Plasma concentrations of the protein in male and female 4-day-old rats were 350 and 740 ng/ml respectively, and declined rapidly to only 3.5 ng/ml at 32 days of age. Concentrations in liver were also high in the newborn rats (200 micrograms/g), and declined from 12 days of age onwards.


Asunto(s)
Animales Recién Nacidos/metabolismo , Hígado/metabolismo , Metalotioneína/metabolismo , Animales , Reacciones Cruzadas , Femenino , Riñón/metabolismo , Masculino , Metalotioneína/sangre , Metalotioneína/inmunología , Ratas , Ratas Endogámicas
15.
Arch Biochem Biophys ; 229(2): 585-95, 1984 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-6367661

RESUMEN

Purine hydroxylase II from Aspergillus nidulans has been purified to near homogeneity. The enzyme has a pI of 5.7, a molecular weight of 300,000, and two subunits with molecular weight of 153,000 each. The enzyme contains 2 FAD, 2 molybdenum atoms, and 4 (2 Fe-2S) iron-sulfur centers per molecule and exhibits broad specificity for reducing and oxidizing substrates. Among the more notable characteristics are the ability to oxidize hypoxanthine and nicotinic acid but not xanthine and virtually complete inactivity with oxygen. Moreover, while the enzyme is inactivated by borate and methanol, it is very resistant to cyanide and arsenite and it not inactivated by allopurinol. At infinite concentrations of reducing and oxidizing substrates, the Km for hypoxanthine was 119 microM, for nicotinic acid was 136 microM, and for NAD+ was 525 microM.


Asunto(s)
Oxidorreductasas de Alcohol/aislamiento & purificación , Aspergillus nidulans/enzimología , Flavina-Adenina Dinucleótido/análisis , Concentración de Iones de Hidrógeno , Proteínas Hierro-Azufre/aislamiento & purificación , Cinética , Sustancias Macromoleculares , Peso Molecular , Molibdeno/análisis , Especificidad por Sustrato
16.
Biochem J ; 227(3): 903-8, 1985 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-4004805

RESUMEN

The degradation of purified 35S-labelled rat liver isometallothioneins (MT) by lysosomal extracts was studied. Zn-MT-I was more readily hydrolysed than Zn-MT-II, but no significant degradation of the Cu-containing metallothioneins could be detected, even after 24 h incubation. The susceptibility of MT to degradation in vitro may be related to the strength of the metal-thiolate bonds. However, the turnover rates of cytosolic MT in vivo, as established by pulse-labelling techniques, are apparently subject to different controls. The half-lives of MT-I and -II in the liver cytosol of Cu2+-injected rats were only 15.4 +/- 1.5 and 18.2 +/- 1.1 h respectively. Approx. 25% of the total liver MT was present in particulate fractions (probably in lysosomes) of the liver and had a half-life of 25.1 +/- 4.1 h.


Asunto(s)
Hígado/metabolismo , Metalotioneína/metabolismo , Animales , Cromatografía en Gel , Cobre/metabolismo , Cisteína/metabolismo , Semivida , Técnicas In Vitro , Masculino , Ratas , Ratas Endogámicas , Fracciones Subcelulares/metabolismo
17.
J Cell Biochem ; 45(1): 30-40, 1991 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-2005182

RESUMEN

One stress response in cells is the ability to survive in an environment containing excessive concentrations of metal ions. This paper reviews current knowledge about cellular and molecular mechanisms involved in the response and adaptation of various fungal species to metal stress. Most cells contain a repertoire of mechanisms to maintain metal homeostasis and prevent metal toxicity. Roles played by glutathione, related (gamma-EC)nG peptides, metallothionein-like polypeptides, and sulfide ions are discussed. In response to cellular metal stress, the biosynthesis of some of these molecules are metalloregulated via intracellular metal sensors. The identify of the metal sensors and the role of metal ions in the regulation of biosynthesis of metallothionein and (gamma-EC)nG peptides are subjects of much current attention and are discussed herein.


Asunto(s)
Farmacorresistencia Microbiana , Hongos/efectos de los fármacos , Metales/farmacología , Farmacorresistencia Microbiana/genética , Hongos/genética , Hongos/metabolismo , Glutatión/metabolismo , Metalotioneína/metabolismo , Sulfuros/metabolismo
18.
J Gen Microbiol ; 135(Pt 2): 273-8, 1989 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-2693595

RESUMEN

Purine hydroxylase I from Aspergillus nidulans was purified 850-fold. The purified preparations exhibited the spectral and catalytic properties, including broad specificity for oxidizing and reducing substrates, typical of molybdenum/flavin/iron-sulphur-containing hydroxylases (oxotransferases).


Asunto(s)
Aspergillus nidulans/enzimología , Cetona Oxidorreductasas/aislamiento & purificación , Xantina Deshidrogenasa/aislamiento & purificación , Electroforesis en Gel de Poliacrilamida , NAD/metabolismo , Especificidad por Sustrato , Xantina Deshidrogenasa/metabolismo
19.
Arch Biochem Biophys ; 265(2): 381-9, 1988 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-3421713

RESUMEN

The metal-gamma-glutamyl peptide complex of Schizosaccharomyces pombe is an oligomer of peptides of the general structure (gamma-Glu-Cys)n-Gly with n defining the number of dipeptide repeats. The complexes induced with either cadmium or copper salts are heterogeneous with respect to the number of repeat units or n. Peptides isolated from two preparations of the Cd-gamma-Glu complex by reverse-phase HPLC at low pH were of an n range of 2 to 6 with n3 and n4 peptides being predominant. In addition to peptides of the mentioned structure, peptides of n3 and n4 without the terminal Gly were isolated. These n3 and n4 desGly peptides were present in an abundance of about 10-20% of the concentration of the parent peptide. Peptides of unique n were studied in Cu(I) reconstitution experiments in an attempt to understand the significance of the peptide length heterogeneity in the oligomeric metal-thiolate cluster. Cu-gamma-Glu complexes were formed with each peptide as determined by the characteristic 260-nm shoulder in the ultraviolet absorption spectrum and luminescence indicative of Cu(I)-thiolate coordination in a solvent-inaccessible environment. Cluster formation also occurs with desGly peptides, so the carboxyl-terminal Gly is not critical for cluster formation. Maximal Cu binding stoichiometry with n3 and n4 peptides was markedly less than the maximal Cu(I) stoichiometry of a peptide mixture or the native complex. Cu ions in complexes formed with unique n peptides were more reactive with bathocuproine than Cu ions in complexes with a peptide n mixture. The results suggest that metal-peptide complexes consisting of peptides differing in n probably exist and not all metal-peptide complexes have the same n peptide constituents.


Asunto(s)
Cobre/análisis , Oligopéptidos/análisis , Péptidos/análisis , Saccharomycetales/análisis , Schizosaccharomyces/análisis , Sitios de Unión , Cromatografía Líquida de Alta Presión , Factores de Elongación de Péptidos/análisis , Factores de Terminación de Péptidos/análisis , Espectrofotometría Ultravioleta
20.
Biochem J ; 307 ( Pt 3): 697-705, 1995 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-7741699

RESUMEN

Room temperature luminescence attributable to Cu(I)-thiolate clusters has been used to probe the transfer of Cu(I) from Cu(I)-glutathione complex to rabbit liver thionein-II and plant metal-binding peptides phytochelatins (gamma-Glu-Cys)2Gly, (gamma-Glu-Cys)3Gly and (gamma-Glu-Cys)4Gly. Reconstitutions were also performed using CuC1. The Cu(I)-binding stoichiometry of metallothionein or phytochelatins was generally independent of the Cu(I) donor. However, the luminescence of the reconstituted metallothionein or phytochelatins was higher when Cu(I)-GSH was the donor. This higher luminescence is presumably due to the stabilizing effect of GSH on Cu(I)-thiolate clusters. As expected, 12 Cu(I) ions were bound per molecule of metallothionein. The Cu(I) binding to phytochelatins depended on their chain length; the binding stoichiometries being 1.25, 2.0 and 2.5 for (gamma-Glu-Cys)2Gly, (gamma-Glu-Cys)3Gly and (gamma-Glu-Cys)4Gly respectively at neutral pH. A reduced stoichiometry for the longer phytochelatins was observed at alkaline pH. No GSH was found to associate with phytochelatins by a gel-filtration assay. The Cu(I) binding to (gamma-Glu-Cys)2Gly and (gamma-Glu-Cys)3Gly occurred in a biphasic manner in the sense that the relative luminescence increased approximately linearly with the amount of Cu(I) up to a certain molar ratio whereafter luminescence increased dramatically upon the binding of additional Cu(I). The luminescence intensity declined once the metal-binding sites were saturated. In analogy with the studies on metallothioneins, biphasic luminescence suggests the formation of two types of Cu(I) clusters in phytochelatins.


Asunto(s)
Cobre/metabolismo , Glutatión/farmacología , Metaloproteínas/metabolismo , Proteínas de Plantas/metabolismo , Secuencia de Aminoácidos , Animales , Transporte Biológico , Cromatografía en Gel , Estabilidad de Medicamentos , Hígado/metabolismo , Mediciones Luminiscentes , Metalotioneína/metabolismo , Datos de Secuencia Molecular , Fitoquelatinas , Conejos , Espectrofotometría Ultravioleta
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