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Titolo:
MITOCHONDRIAL SE-75 UPTAKE AND REGULATION REVEALED BY KINETIC-ANALYSIS
Autore:
LALITHA K; RANI P;
Indirizzi:
INDIAN INST TECHNOL,DEPT CHEM,HSB 264 MADRAS 600036 TAMIL NADU INDIA
Titolo Testata:
Biological trace element research
fascicolo: 1, volume: 49, anno: 1995,
pagine: 21 - 42
SICI:
0163-4984(1995)49:1<21:MSUARR>2.0.ZU;2-1
Fonte:
ISI
Lingua:
ENG
Soggetto:
GLUTATHIONE-PEROXIDASE; MUSCA-DOMESTICA; RAT; TRANSPORT; SELENATE; SELENOCYSTEINE; SELENOPROTEINS; SELENOENZYME; DEFICIENCY; PROTEIN;
Keywords:
SELENIUM UPTAKE; MITOCHONDRIAL SELENIUM TRANSPORT; MEMBRANE THIOLS; KINETICS OF TRANSPORT; SULFHYDRYL INHIBITORS; INSECT MITOCHONDRIA (C-CEPHALONICA);
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
48
Recensione:
Indirizzi per estratti:
Citazione:
K. Lalitha e P. Rani, "MITOCHONDRIAL SE-75 UPTAKE AND REGULATION REVEALED BY KINETIC-ANALYSIS", Biological trace element research, 49(1), 1995, pp. 21-42

Abstract

Uptake of (Na2SeO3)-Se-75 by mitochondria of the larvae of the insectC. cephalonica reared at different dietary selenium (Se) levels revealed: 1. A proportional increase in the uptake with externally added (Na2SeO3)-Se-75 in concentrations upto 25.32 mu M; and 2. At each added selenite concentration, an increase up to 60 min, with linearity up to15-30 min. A differential affinity for (Na2SeO3)-Se-75 was elicited in the mitochondrial protein fractions of different dietary Se groups and correlated well with the pattern and the ratio of distribution of incorporated Se-75 in protein to nonprotein fractions. Kinetic studies on Se-75 uptake by whole mitochondria negated passive diffusion of selenite and revealed a trend of negative cooperativity, confirmed by Hill and Scatchard plots. Half saturation value was estimated to be approx 13 nmole Se/mg mitochondrial protein. Scatchard plot for Se-75 uptake was biphasic and the high affinity binding sites were estimated to be around 5 nmole/mg mitochondrial protein. Calculated dissociation constants revealed maximal affinity for Se-75 in the 1.5 ppm group (K-Se 0.0034 nM) and minimal in the basal group (K-Se 0.007 nM). In the mitochondria of all the three dietary Se groups, the estimated low affinity sites amounted to be 15-19 nmole/mg mitochondrial protein. Inherent Se in the mitochondria of the high Se group positively enhanced the incorporation of Se-75 in the mitochondrial protein fraction. About 20-30% of the total uptake was indicated to be energy linked as revealed by studies with respiratory inhibitors. Addition of sulfite and sulfate(5-25 mu M) in the medium, inhibited Se-75 uptake by 35-55%, suggestive of the involvement of the dicarboxylate port. Thiol interactive Se-75 uptake was confirmed by the inhibition mediated by mersalyl and NEMup to 50-70%. The study revealed thiol-selenite interactions of metabolic significance during selenite uptake.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 20/01/21 alle ore 15:37:18