Chain Length Effects of <em>n</em>-Alkyl 1-Oxygen- and <em>n</em>-Alkyl 1-Thio-β-D-Xylopyranosides on β-D-Xylosidases.

A method involving the use of sieves and differential centrifugation for the preparation and separation of basement membranes from human renal tubules and glomeruli is described. Electron microscopic examination of the material obtained shows the glomerular membrane as a single dense structure, while the tubular membrane is composed of two dense layers separated by a space filled with loose fibrils exhibiting the same periodicity as collagen. The carbohydrate composition of both types of membranes is the same but tubular membranes have a lower content of some specific sugars. Differences also exist in amino acid composition. The content in hydroxylysine is higher in the glomerular membrane while the content in hydroxyproline is higher in the tubular membrane. Gel electrophoresis after solubilization of the material demonstrates the presence of two, may be three, major proteins. [ABSTRACT FROM AUTHOR]