THE REMOVAL OF CARBOHYDRATES FROM RICIN WITH ENDOGLYCOSIDASES-H, ENDOGLYCOSIDASE-F AND ENDOGLYCOSIDASE-D AND ALPHA-MANNOSIDASE
THE REMOVAL OF CARBOHYDRATES FROM RICIN WITH ENDOGLYCOSIDASES-H, ENDOGLYCOSIDASE-F AND ENDOGLYCOSIDASE-D AND ALPHA-MANNOSIDASE
复制标题
DOI：
10.1016/0304-4165(85)90119-9
复制
发表时间：
1985-01-01
期刊：
影响因子：
--
通讯作者：
WILSON, G
中科院分区：
文献类型：
--
作者：
FOXWELL, BMJ;DONOVAN, TA;WILSON, G
Targeting ricin to designated cell types in animals by its linkage to specific antibodies was explored. There was evidence that the mannose-containing oligosaccharide chains on ricin were recognized by reticuloendothelial cells in the liver and spleen and so caused the immunotoxins to be removed rapidly from the blood stream. The carbohydrate composition of ricin was analyzed and enzymic methods for removing the carbohydrate were examined. The carbohydrate analysis of ricin A-chain revealed the presence of 1 residue of xylose and 1 of fucose in addition to mannose and N-cetylglycosamine which had been detected previously. The B-chain contained only mannose and N-acetylglycosamine. Ricin A-chain was heterogeneous containing 2 components of MW 30,000 and 32,000. The heavier form of the A-chain contained an extra carbohydrate unit which was heterogeneous with respect to concanavalin A binding and sensitivity to endoglycosidase H. The lower MW form of A-chain did not bind concanavalin A and was insusceptible to endoglycosidases. Only 1 of the 2 high mannose oligosaccharide units on the isolated B-chain was removed by endoglycosidases H or F, whereas both were removable after denaturation of the polypeptide by SDS [sodium dodecyl sulfate]. The isolated A- and B-chains were sensitive to .alpha.-mannosidase. Intact ricin was resistant to endoglycosidase treatment and was only slightly sensitive to .alpha.-mannosidase. The addition of SDS allowed endoglycosidase H to remove the B-chain oligosaccharides from intact ricin and increased the toxin''s sensitivity to .alpha.-mannosidase. Extensive enzymic deglycosylation of ricin may only be possible if the A- and B-chains are first separated, treated with enzymes and then recombined to form the toxin.
