A colorimetric assay for glycoproteins based on the periodic acid/Schiff stain [proceedings].

of trypsin without EDTA. A monolayer of radioactively labelled BHK cells was incubated at 37°C for2min in 0.25 % trypsin; one half of the cells in suspension were harvested, washed and assayed for adhesion, and the other half of the cells were incubated for a further 15min in 0.25% trypsin before harvesting, washing and assaying for adhesion. Cells incubated in trypsin for only 2min did not show a Mn2+-stimulated adhesion that was much greater than the CaZ+/Mg2+-stimulated adhesion. In contrast, BHK cells incubated for 15min in trypsin showed an Mn'+-stimulated adhesion that was twice that for the Ca2+/Mg2+-stimulated adhesion. These cells completely excluded Trypan Blue. When such strongly trypsin-treated '4C-labelled BHK cells were preincubated in complete growth medium for up to 60min before assaying for adhesion, this difference between adhesion in Mn2+ buffer and Ca2+/MgZ+ buffer decreased. Thus the CaZ+/Mg2+-stimulated adhesion was 51 and 86% respectively of the MnZ+stimulated adhesion for BHK cells that had been freshly treated with trypsin and for the same cells that had been allowed to recover for 60min in growth medium. MnZ+ is considered to affect the cytoskeleton of the cell, possibly by its release of membrane-bound Ca2+ (Rabinowitch & DeStefano, 1973; Gwynn et al., 1976). Our experiments show, firstly, that Mn2+ causes abnormal spreading and does not replace the requirement for CaZ+/Mg2+ and secondly, that changes that occur with cell transformation or proteolysis for trypsin potentiate this atypical MnZ+ effect.