New carbohydrate site in mutant antithrombin (7 Ile----Asn) with decreased heparin affinity.
A mutant antithrombin was isolated from the plasma of a patient with pulmonary embolism. The new protein, which accounted for 55% of the antithrombin, had decreased heparin affinity and contained two components when analysed on the basis of either charge or molecular mass. Sialidase and endo-beta-N-acetylglucosaminidase F treatment suggested that this heterogeneity was due to a partial glycosylation occurring at a new carbohydrate attachment sequence. Peptide mapping by reverse-phase HPLC showed that the abnormality involved the N-terminal tryptic peptide. Sequence analysis demonstrated that the underlying mutation was 7 Ile----Asn which introduces a new Asn-Cys-Thr glycosylation sequence. This new oligosaccharide attachment site occupies the base of the proposed heparin-binding site, and the finding explains the consequent decrease in heparin affinity.
Brennan
S O
SO
Pathology Department, Christchurch School of Medicine, Christchurch Hospital, New Zealand.
Borg
J Y
JY
George
P M
PM
Soria
C
C
Soria
J
J
Caen
J
J
Carrell
R W
RW
D000990:Antithrombin III / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D001216:Asparagine; D005260:Female; D014644:Genetic Variation; D006493:Heparin / Q000378:metabolism*; D006801:Humans; D007532:Isoleucine; D007700:Kinetics; D008875:Middle Aged; D009154:Mutation; D010449:Peptide Mapping; D010455:Peptides / Q000032:analysis; D011485:Protein Binding
D010455:Peptides; D007532:Isoleucine; D001216:Asparagine; D000990:Antithrombin III; D006493:Heparin