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A Sreenivasan

Publications and source records attributed to A Sreenivasan.

At least 73 records · Page 4Linked to original sources
PubMed1971

Study of soluble lipoprotein in rat liver mitochondria.

1. A water-soluble lipoprotein was isolated and purified from osmotically shocked preparations of rat liver mitochondria by using a technique of Sephadex-sandwich disc electrophoresis. 2. The purified lipoprotein migrates as a distinct sharp zone in high-resolution electrophoretic systems, indicating high degree of purity. 3. The lipoprotein resembles mitochondrial membranes with respect to lipid composition and lipid/protein ratio. 4. The lipoprotein and its apoprotein fraction obtained by delipidization at -18 degrees C to -20 degrees C have common properties with respect to their fluorescence spectra, instability to storage and electrophoretic mobility. 5. The purified lipoprotein has an excitation maximum at 325nm and a fluorescence maximum at 418nm. 6. Storage at 4 degrees C for 4 days or repeated freezing and thawing results in 15-30% decrease in electrophoretic mobility. 7. The patterns of incorporation in vitro of [1-(14)C]leucine into proteins of the soluble lipoprotein and of mitochondrial membrane of isolated rat liver mitochondria suggest a probable precursor role for the apoprotein in the formation of mitochondrial membrane protein. 8. Lipoprotein preparations isolated from mitochondrial fractions of rat kidney, brain and heart and of chicken and mouse liver resemble closely that obtained from rat liver mitochondria, suggesting that the soluble lipoprotein could be a distinct entity of mitochondrial origin.

Animals↗
PubMed1970

Heterogeneity of rat liver mitochondrial fractions and the effect of tri-iodothyronine on their protein turnover.

1. Rat liver mitochondria were separated into heavy, light and fluffy fractions by differential centrifugation under standard conditions. 2. All mitochondrial fractions possessed soluble as well as membrane-bound enzymes typical of mitochondria. 3. The heavy fraction represented the stable mitochondrial structures and the fluffy particles appear to be loosely coupled. 4. The light mitochondrial fraction lacked the ability of coupled phosphorylation. 5. A study of mobility and isoelectric pH indicated a similarity in the basic membrane structure of all the mitochondrial fractions. 6. The turnover rates of proteins in the heavy and fluffy particles were almost identical; however, this rate was rapid for the light mitochondrial fraction. 7. On treatment with 3,3',5-tri-iodo-l-thyronine, succinoxidase activity was maximally stimulated much earlier in the light mitochondrial fraction than in the heavy fraction. The activity of the fluffy particles, however, remained almost unaffected. 8. Malate dehydrogenase activity in all the mitochondrial fractions was stimulated only at 40h after tri-iodothyronine treatment. 9. The pattern of incorporation of dl-[1-(14)C]leucine in vivo in the tri-iodothyronine-treated animals indicated a rapid initial incorporation and high synthetic ability of the light mitochondrial fraction. 10. The turnover pattern of proteins of the mitochondrial fractions from animals receiving repeated doses of tri-iodothyronine was remarkably different from the normal pattern and suggested that preformed soluble protein units may be incorporated in the light mitochondrial fraction during maturation to form the stable heavy mitochondria. 11. The amount of light-mitochondrial proteins decreased by 40% on thyroidectomy and increased by 160% on treatment with tri-iodothyronine. 12. The possible significance of these results is discussed in relation to mitochondrial genesis.

Adenosine Triphosphatases↗
PubMed1968

Two forms of aspartate aminotransferase in rat liver and kidney mitochondria.

1. Butan-1-ol solubilizes that portion of rat liver mitochondrial aspartate aminotransferase (EC 2.6.1.1) that cannot be solubilized by ultrasonics and other treatments. 2. A difference in electrophoretic mobilities, chromatographic behaviour and solubility characteristics between the enzymes solubilized by ultrasonic treatment and by butan-1-ol was observed, suggesting the occurrence of two forms of this enzyme in rat liver mitochondria. 3. Half the aspartate aminotransferase activity of rat kidney homogenate was present in a high-speed supernatant fraction, the remainder being in the mitochondria. 4. A considerable increase in aspartate aminotransferase activity was observed when kidney mitochondrial suspensions were treated with ultrasonics or detergents. 5. All the activity after maximum activation was recoverable in the supernatant after centrifugation at 105000g for 1hr. 6. The electrophoretic mobility of the kidney mitochondrial enzyme was cathodic and that of the supernatant enzyme anodic. 7. Cortisone administration increased the activities of both mitochondrial and supernatant aspartate aminotransferases of liver, but only that of the supernatant enzyme of kidney.

Alcohols↗