Lysosomes in Tetrahymena pyriformis I. Some properties and lysosomal localization of acid hydrolases
✍ Scribed by Miklós Müller; Pierre Baudhuin; Christian De Duve
- Publisher
- John Wiley and Sons
- Year
- 1966
- Tongue
- English
- Weight
- 835 KB
- Volume
- 68
- Category
- Article
- ISSN
- 0021-9541
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✦ Synopsis
In homogenates of Tetrahymena pyriformis, five hydrolasesphosphatase, ribonuclease, deoxyribonuclease, proteinase, amylasewith acid pH optima were found. Over 75% of their activity is sedimentable with a centrifugal force of 250,000 g. min. Only 17% of the acid phosphatase and ribonuclease is active when assayed in the presence of 0.25 M sucrose at 0". Exposure to a lowered osmotic pressure, freezing and thawing, and incubation at temperatures over 0" result in activation of the latent phosphatase and ribonuclease. After isopycnic centrifugation in a sucrose density gradient the hydrolases show a broad distribution which differs greatly from those of enzymes associated with mitochondria ( succinate dehydrogenase) or with peroxisomes (catalase). The results are interpreted as evidence that the five acid hydrolases studied are localized in lysosomes which represent a distinct population of subcellular particles in Tetrahymena.
Methods
T. pyriforrnis cells, var. I, mating type IV were cultivated at room temperature (22-23°C) in a medium of the following composition : Difco Tryptone 1 % , Difco Yeast extract 0.05%; p H of the medium about