Factor XII Tenri (Y34C), a rare cross-reacting material (CRM)-negative
factor XII deficiency, was identified in a 71-yr-old Japanese woman with
angina pectoris. In the patient's plasma,
factor XII activity and
antigen levels were only 1.6% and 5.0%, respectively, of those seen in a normal subject. Immunoblot analysis showed that the secreted
factor XII Tenri existed not only as a monomer (76 kDa), but also in complexes with apparent molecular weights of approximately 115, 140, 190, 215, and 225 kDa. After reduction with
2-mercaptoethanol, the
factor XII Tenri contained in the complexes was completely converted to monomeric form on immunoblot patterns. It appeared that some of the secreted
factor XII Tenri formed several types of
disulfide-linked complexes, including
a factor XII-alpha1-microglobulin complex, through a newly generated Cys residue. The monomeric form of
factor XII Tenri, like normal
factor XII, was degraded into 2 major fragments with molecular weights of approximately 45 kDa and 30 kDa following mixing with activated partial-thromboplastin-time measuring
reagent (
cephalin and
ellagic acid), whereas the
factor XII Tenri that formed the complexes was not. This indicates that the
factor XII Tenri present in
disulfide-linked complexes with other
proteins (and itself) is not converted to active forms, suggesting that attached
proteins obstruct or delay the activation of
factor XII via an inhibition of its binding to a negatively charged surface in vitro.