TY - JOUR
T1 - Identification of the major 4-methylumbelliferyl p-guanidinobenzoate-hydrolyzing plasma protein in cystic fibrosis
T2 - Implication for intrauterine and heterozygote detection
AU - Branchini, Bruce R.
AU - Salituro, Gino M.
AU - Rosenstein, Beryl J.
PY - 1983/11
Y1 - 1983/11
N2 - Measurement of 4-methylumbelliferyIP-guanidinobenzoate (MUGB)-hydrolyzing activity in the plasma of normal controls, cystic fibrosis (CF) heterozygotes, and CF homozygotes did not support previously reported (35) differences in MUGB-hydrolyzing activity. We identified human plasma albumin as the major source of MUGB-hydrolyzing activity by comparison of our plasma results to those obtained with physiologic concentrations of commercial albumin samples. Substantiating evidence was obtained from gel filtration experiments and correlation of albumin levels in CF plasma with MUGB titers. We found essentially no proteolytic activity towards dinitrophenylprotamine sulfate associated with commercial albumin samples. It appears that the reaction between human albumin and MUGB represents a weak esterase activity, perhaps involving the acylation of a specific site(s) on the protein. Hypoalbuminemia has been documented (8) in some CF patients. Low albumin concentrations, indicated by MUGB titers <190 nmole methylumbelliferone/ml plasma, were found in 42% of CF homozygotes, 6% of heterozygotes, and 4% of controls. Gel filtration studies of a normal amniotic fluid supernatant indicated that albumin was the major MUGB-hydrolyzing substance in this fluid. We conclude that MUGB abnormalities are not associated with the basic gene defect in CF and cannot be used as the basis of a test for intrauterine or heterozygote detection.
AB - Measurement of 4-methylumbelliferyIP-guanidinobenzoate (MUGB)-hydrolyzing activity in the plasma of normal controls, cystic fibrosis (CF) heterozygotes, and CF homozygotes did not support previously reported (35) differences in MUGB-hydrolyzing activity. We identified human plasma albumin as the major source of MUGB-hydrolyzing activity by comparison of our plasma results to those obtained with physiologic concentrations of commercial albumin samples. Substantiating evidence was obtained from gel filtration experiments and correlation of albumin levels in CF plasma with MUGB titers. We found essentially no proteolytic activity towards dinitrophenylprotamine sulfate associated with commercial albumin samples. It appears that the reaction between human albumin and MUGB represents a weak esterase activity, perhaps involving the acylation of a specific site(s) on the protein. Hypoalbuminemia has been documented (8) in some CF patients. Low albumin concentrations, indicated by MUGB titers <190 nmole methylumbelliferone/ml plasma, were found in 42% of CF homozygotes, 6% of heterozygotes, and 4% of controls. Gel filtration studies of a normal amniotic fluid supernatant indicated that albumin was the major MUGB-hydrolyzing substance in this fluid. We conclude that MUGB abnormalities are not associated with the basic gene defect in CF and cannot be used as the basis of a test for intrauterine or heterozygote detection.
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U2 - 10.1203/00006450-198311000-00003
DO - 10.1203/00006450-198311000-00003
M3 - Article
C2 - 6646895
AN - SCOPUS:0021082565
SN - 0031-3998
VL - 17
SP - 851
EP - 855
JO - Pediatric research
JF - Pediatric research
IS - 11
ER -