GENETICALLY POLYMORPHIC ALPHA-L-FUCOSIDASE (FUCA1) ISOZYMES DETECTED IN BLOOD-PLASMA

The main isozyme patterns of desialylated blood plasma or serum alpha- L-fucosidase (FUCA) were found to be almost identical to those of seme n, urine, placental extracts, and leukocyte lysates, when detected by polyacrylamide gel isoelectric focusing, and activity staining using t he fluorogenic substrate 4-methylumbelliferyl-alpha-L-fucopyranoside. Three phenotypes (1, 2-1, and 2) determined from plasma samples were i dentical to the phenotypes from urine and leukocyte lysates from the s ame individuals. A population study of plasma samples collected from 4 85 Japanese individuals indicated that the frequencies of the FUCA11 and FUCA12 alleles were 0.7505 and 0.2495, respectively. The mean pla sma enzyme activities (+/- SD) of the three phenotypes were 318.8 +/- 116.7 nmol/ml per h for type 1, 268.0 +/- 108.3 nmol/ml per h for type 2-1, and 233.2 +/- 84.4 nmol/ml per h for type 2. The mean activities of types 1 and 2 suggest that, on average, the FUCA11 gene product i n plasma has about 1.4 times the activity of FUCA12.