Differences in the binding affinities of dimeric concanavalin A (including acetyl and succinyl derivatives) and tetrameric concanavalin A with large oligomannose-type glycopeptides.
Dimeric derivatives of concanavalin A (Con A) such as acetyl- and succinyl-Con A have been used for years as probes of cellular membranes. The altered binding and biological activities of these derivatives relative to native tetrameric Con A have generally been attributed to their reduced valence. However, the present study shows that acetyl- and succinyl-Con A possess lower affinities than tetrameric Con A toward certain oligomannose-type glycopeptides which are found on the surface of cells. It has previously been shown that native tetrameric Con A possesses 5-30-fold enhanced affinities toward Man7-Man9 oligomannose-type glycopeptides, respectively, relative to Man5 and Man6 oligomannose-type glycopeptides [Bhattacharyya, L., & Brewer, C. F. (1989) Eur. J. Biochem. 178, 721-726]. Using titration microcalorimetry and hemagglutination inhibition measurements, methyl alpha-D-mannopyranoside, methyl 3,6-di-O-(alpha-D-mannopyranosyl)-alpha-D-mannopyranoside (which binds with about 60-fold higher affinity than methyl alpha-D-mannopyranoside and is the major Con A binding epitope on oligomannose-type carbohydrates), and a Man5 oligomannose-type oligosaccharide are shown to bind to underivatized dimeric Con A at pH 5.2 and acetyl- and succinyl-Con A at pH 7.2 with affinities equal to those of native tetrameric Con A. However, a mixture of Man7 and Man8 glycopeptides and a Man9 oligomannose-type glycopeptide were shown to bind to underivatized dimeric Con A and acetyl- and succinyl-Con A with affinities only about 2-fold higher than the Man5 oligosaccharide, in contrast to the higher affinities of native tetrameric Con A for these carbohydrates.(ABSTRACT TRUNCATED AT 250 WORDS)
Mandal
D K
DK
Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York 10461.
Brewer
C F
CF
D001665:Binding Sites; D002151:Calorimetry; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D003208:Concanavalin A / Q000737:chemistry / Q000378:metabolism*; D006020:Glycopeptides / Q000737:chemistry / Q000378:metabolism*; D006385:Hemagglutination Inhibition Tests; D046911:Macromolecular Substances; D008358:Mannose / Q000378:metabolism*; D008969:Molecular Sequence Data
D006020:Glycopeptides; D046911:Macromolecular Substances; D003208:Concanavalin A; C019558:succinylconcanavalin A; C030718:acetylated concanavalin A; D008358:Mannose