Basement membranes from vascular and nonvascular canine tissue were analyzed chemically and structurally. Basement membranes which derive from different embryologic cell lines were qualitatively similar but differed quantitatively in their amino acid and carbohydrate composition. In terms of residues per 1000 residues anterior lens capsule contained hydroxylysine 32, hydroxyproline 99.5, and glycine 288, compared with 20, 83.8, and 230 residues, respectively, for Descemet’s membrane. Glomerular, alveolar, and choroid plexus basement membranes contained hydroxylysine 24, 6.8, and 9 residues, hydroxyproline 65, 35, and 48 residues, and glycine 229, 222, and 235 residues, respectively. The carbohydrate content was high in all, ranging from 12.5 and, 10.5% in anterior lens capsule and Descemet’s membrane to 10.25, 6.7, and 7.3% in basement membranes from the glomerulus, alveolus, and choroid plexus, respectively. An acid-soluble collagen was obtained from anterior lens capsule, Descemet’xs membrane and glomerular basement membrane after limited digestion with pronase or pepsin. Digestion with pepsin at 4° for 16 hr yields a collagen with an intrinsic viscosity of 13 d/g, while digestion with pronase at 4° for 10 and 24 hr yields collagen fragments with intrinsic viscosities of 10 and 5.4 dl per g, respectively. An acid-insoluble collagenous component with noncollagen polypeptides still attached to it was obtained from basement membranes of the glomerulus, alveolus, choroid plexus, and Descemet’s membrane. The compositional differences among basement membranes reflect the proportion of the noncollagen polypeptides associated with the collagen and are thought to determine the functional behavior of the various basement membranes. © 1969, American Chemical Society. All rights reserved.
