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Production of amino acids by analog-resistant mutants of the cyanobacterium Spirulina platensis.
No full textCompared with the parental strain, a Spirulina platensis mutant that is resistant to ethionine incorporated methionine into protein at a reduced rate, whereas ethionine incorporation was practically nil. The methionyl-tRNA synthetase present in crude extracts from the resistant strain showed a reduced affinity for methionine and ethionine
A bacterial extracellular proteinase degrading silk fibroin
No full textThe bacterium Variovorax paradoxus, grown in a minimal medium in which silk broin represents the sole source of carbon and nitrogen, produces an extracellular protease that hydrolyzes broin as well as casein and, to a smaller extent, collagen and albumin. The optimal pH for activity was found to be in the acid range (optimum pH 5.8{6.4) and the enzyme activity was stimulated by the addition of divalent cations, either manganese or magnesium. Gel permeation chromatography and SDS-PAGE provided evidence that the native enzyme is a monomer with a Mr of ca. 21 kDa
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