On the subunit structure of particulate aminopeptidase from pig kidney

Incorporation of hydrophobic aminopeptidase from hog kidney into egg lecithin liposomes: Number and orientation of aminopeptidase molecules in the lecithin vesicles

“…borders [4] although the two brush borders are very similar, both morphologically and biochemically.…”

“…Detergent-solubilised aminopeptidase was prepared according to [4], its trypsin-solubilised form according to [9]. Egg lecithin, grade I, was obtained from LipidProducts (South Nuttield, UK) and stored as a chloroform solution under nitrogen at -20°C.…”

“…Aminopeptidase activity was assayed using Lleucine- 4 material (approx. 10% of the total lecithin and approx.…”

“…they are composed of approx. 5800 lecithin molecules per 3A, and in the electron micrograph, see fig.2C), the phospholipid/ aminopeptidase ratios given above correspond to liposome populations where each liposome contains either I,2 or 3 aminopeptidase dimers of 280 000 daltons [4] , respectively (see also [ 151).…”

“…Extraction with Triton X-100 yields an aggregated form of the enzyme which can be transformed into a low molecular weight form by the action of trypsin [4]. During this transformation a fragment of approximately 10 000 daltons is released; this probably represents the hydrophobic portion which anchors the protein to the lipid matrix of the original membrane [4].…”