Stabilisation of some of the protein synthesis components in the thermophilic fungus,Humicola lanuginosa |
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Authors: | Anil K Joshi Joseph D Cherayil |
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Institution: | (1) Department of Biochemistry, Indian Institute of Science, 560012 Bangalore, India;(2) Present address: Department of Biochemistry, University of California, 94720 Berkeley, California, USA |
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Abstract: | The thermal stabilities of tRNA from the thermophilic fungus,Humicola lanuginose were compared with that from the mesophilic yeast,Candida utilis, by measuring the increase in the optical density with temperature. tRNAs from both the species were stable in the presence
of millimolar quantities of magnesium chloride upto 50°C, the optimum growth temperature of the fungus. Aminoacyl tRNA synthetases
were maximally active at 40°C under thein vitro assay conditions. They were fractionated and one species of valine tRNA synthetase was purified to homogeneity. The purified
enzyme was protected against inactivation to varying degrees when preincubated with the substrates valine, tRNA and ATP as
well as spermine. Protein turnover studies showed that the rate of turnover was higher at higher temperatures. It was concluded
from these results that the protein synthesizing machinery of this fungus has no intrinsic stability but it is stabilised
by intracellular factors. Higher rate of protein turnover also plays a role for growth at higher temperature. |
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Keywords: | Thermophilic fungus stabilisation of synthetase rate of protein turnover Humicola lanuginosa |
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