A Study of Dipeptidyl Aminopeptidase IV in the Sera of Japanese FAP Patients
We investigated how soluble serum variant prealbumin changes into insoluble depositing amyloid in the tissues of familial amyloidotic polyneuropathy (FAP) patients. We examined the activity of dipeptidyl aminopeptidase (DAP) IV in the sera of FAP patients, paying attension to the heterogeneity of N-terminal amino acids of amyloid variant prealbumin. Sera from eleven FAP patients, six asymptomatic FAP family members including two FAP carriers and one hundred nunety nine normal controls were submitted to study. Mean DAP IV activity in the sera of FAP patients was 31.35, 2SD=12.58 (¼mol/min/L serum, 37 °C), which was significantly lower (p<0.01) than that of the normal controls. DAP IV activity in the sera of FAP carriers was also low. DAP IV is a serine enzyme which is believed both to metabolize GLY-PRO-peptide from collagen and to localize in the membrane fraction. Although the exact reason for low activity of DAP IV in FAP patients remains unclear, this low activity may result from emaciation in the natural clinical course. Another possibility is that low DAP IV activity of unknown cause plays a part in the partial degradation of variant prealbumin, resulting in amyloid deposition in the tissues.
KeywordsArthritis Leukemia Glycine Serine Proline
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