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Cobalamin R binder as a possible model molecule for glycoprotein study in cystic fibrosis
Insights
Cystic fibrosis alters salivary R binder, an acidic glycoprotein binding cobalamin, increasing its isoelectric point and reducing microheterogeneity. These changes were not seen in serum R binder or linked to saliva enzyme activity.
Area of Science:
- Biochemistry
- Glycoprotein Metabolism
- Cystic Fibrosis Research
Background:
- R binder is an acidic glycoprotein that binds cobalamin.
- Cystic fibrosis (CF) is a genetic disorder affecting multiple organs.
- Understanding glycoprotein alterations in CF is crucial.
Purpose of the Study:
- To compare the isoprotein pattern of R binder in cystic fibrosis patients and healthy individuals.
- To investigate potential modifications in R binder associated with CF.
- To assess R binder as a model for studying glycoprotein metabolism in CF.
Main Methods:
- Semi-purified R binder was isolated from saliva and sera.
- Isoprotein patterns were analyzed using isoelectric focusing.
- Comparisons were made between 8 CF patients and 5 healthy children.
Main Results:
- Salivary R binder in CF patients showed an increased mean isoelectric point (3.78 to 4.34) and reduced microheterogeneity compared to controls.
- These modifications were not observed in R binder from CF patient sera.
- No correlation was found between salivary R binder changes and specific saliva enzyme activities (beta-galactosidase, alpha-mannosidase, alpha-L-fucosidase, neuraminidase).
Conclusions:
- R binder's physicochemical properties are altered in the saliva of cystic fibrosis patients.
- Salivary R binder modifications in CF do not appear to be directly linked to the measured enzymatic activities.
- R binder serves as a potential model molecule for investigating glycoprotein metabolism in cystic fibrosis due to its composition and widespread presence.
Abstract:
The isoprotein pattern of semi-purified R binder (an acidic glycoprotein which binds cobalamin) from saliva and sera of 8 cystic fibrosis patients was compared to that of R binder from samples of 5 healthy children. In cases of cystic fibrosis, the mean isoelectric point of salivary R binder was increased from 3.78 up to 4.34 and its microheterogeneity was reduced. These significant physicochemical modifications were not observed with R binder from cystic fibrosis sera and they did not correlate with the beta-galactosidase, alpha-mannosidase, alpha-L-fucosidase nor neuraminidase activity of saliva. We propose the R binder as a model molecule to study the glycoprotein metabolism in cystic fibrosis since it contains 30-40% carbohydrate, is easily complexed with cyano[57Co]cobalamin and is present in most tissues and fluids of the human organism.