= Rat-liver acid-phosphatase latency experiment
In the 1951 study by <Jacques Berthet> and <Christian de Duve>, <liver> from fasted rats was immediately chilled in an ice-cold isotonic <chemical solution>. The tissue was generally pressed through wire mesh; the weighed pulp was homogenized in cold $0.25\,\mathrm{mol\,L^{-1}}$ <sucrose> using a glass <Potter-Elvehjem homogenizer>. Their <acid phosphatase> test concerned activity toward added <glycerophosphate> at <pH> $5$: the readout was <substrate> <hydrolysis>, rather than an image of a particle.<Tissue fractionation studies. 1. The existence of a mitochondria-linked, enzymically inactive form of acid phosphatase in rat-liver tissue by Jacques Berthet and Christian de Duve>[Berthet and de Duve (1951), Tissue fractionation studies. 1, printed p. 174, introduction and Methods: Fractionation of tissue constituents; inspected first-page text]{ref}
<Christian de Duve>'s retrospective describes successive <centrifugation> steps, separating <centrifugation pellets> and <supernatants>, and comparing <enzyme> distributions across the recovered fractions. Membrane disruption exposed previously inaccessible <acid phosphatase> activity, providing the crucial comparison with the membrane-preserving preparation. Joint fractionation patterns and release behavior of several <acid hydrolases> supported a shared population of digestive particles. By 1955, this evidence supported the <lysosome> concept.<Exploring Cells with a Centrifuge by Christian de Duve>[Exploring Cells with a Centrifuge, printed pp. 152–153: preparation and differential fractionation; pp. 156–159, Figures 4–7: enzyme distributions, disruption and latency]{ref}
The inference was biochemical: a barrier restricted access to active <enzymes>. Co-sedimentation could confuse distinct particles; a crude mitochondrial fraction did not establish residence inside <mitochondria>. <Lysosomal enzyme latency> neither images an <organelle> nor determines its shape. <Electron microscopy> of enriched fractions supplied separate morphological evidence.<Exploring Cells with a Centrifuge by Christian de Duve>[Printed pp. 153–157: mixed populations and distribution patterns; pp. 161–164: incomplete separation and subsequent electron microscopy of lysosome-rich fractions]{ref}
Back to article page
