Advancing the Development of Glycated Protein Biosensing Technology

Abstract We developed a simple and highly sensitive RIA for glycated protein (GP), and used it to measure GP in serum and urine from 15 normal controls and 30 diabetics (14 with urinary excretion rate of albumin, Ualb less than 15 micrograms/min, group A; nine with 15 less than or equal to Ualb less than or equal to 150 micrograms/min, group B; and seven with Ualb greater than 150 micrograms/min, group C). The mean serum concentration of GP was above normal in all groups of diabetics, and the mean glycation ratios of serum protein (SGP) were higher in groups B and C than in normal subjects. Urinary concentrations of GP also were increased in groups B and C, although the glycation ratio of urinary protein (UGP) was decreased in group C. Consequently, the selectivity of urinary excretion of GP (UGP/SGP) was significantly decreased in group C. Moreover, there was a significant difference in the mean values of selectivity between groups of patients with various degrees of retinopathy. We suggest that measurements of serum and urinary GP are useful to evaluate the progression of diabetic complications.

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Kinetics of Whey Protein Glycation Using Dextran and the Dry-Heating Method

Foods ◽

10.3390/foods8110528 ◽

2019 ◽

Vol 8 (11) ◽

pp. 528 ◽

Cited By ~ 1

Author(s):

Na Li ◽

Abhiram Arunkumar ◽

Mark R. Etzel

Keyword(s):

Sodium Dodecyl Sulfate ◽

Whey Protein ◽

Chromatographic Analysis ◽

Sodium Dodecyl ◽

Protein Glycation ◽

Heating Method ◽

Glycated Protein ◽

Industrial Manufacture ◽

Dodecyl Sulfate ◽

Dry Heating

Glycation of proteins by polysaccharides via the Maillard reaction improves the functional properties of proteins in foods, such as solubility, heat stability, emulsification, foaming, and gelation. Glycation is achieved by either the dry heating or the wet heating method, and considerable research has been reported on the functionality of the reaction mixture as tested in foods. While the characteristics of the glycates in foods have been well studied, the kinetics and equilibrium yield of the protein-polysaccharide glycation reaction has received little attention. Industrial manufacture of the glycates will require understanding the kinetics and yield of the glycation reaction. This work examined the glycation of whey protein isolate (WPI) and glycomacropeptide (GMP) by using dextran and the dry-heating method at 70 °C and 80% relative humidity. The disappearance of un-glycated protein and the creation of glycated protein were observed using chromatographic analysis and fluorescence laser densitometry of sodium dodecyl sulfate-polyacrylamide gels. Data were fit using a first-order reversible kinetic model. The rate constants measured for the disappearance of un-glycated protein by sodium dodecyl sulfate-polyacrylamide (SDS-PAGE) (k = 0.33 h−1) and by chromatographic analysis (k = 0.38 h−1) were not statistically different from each other for WPI-dextran glycation. Dextran glycation of GMP was slower than for WPI (k = 0.13 h−1). The slower rate of glycation of GMP was attributed to the 50% lower Lys content of GMP compared to WPI. Yield for the dry-heating dextran glycation method was 89% for WPI and 87% for GMP. The present work is useful to the food industry to expand the use of glycated proteins in creating new food products.

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Glycation and inactivation of sorbitol dehydrogenase in normal and diabetic rats

Biochemical Journal ◽

10.1042/bj3180119 ◽

1996 ◽

Vol 318 (1) ◽

pp. 119-123 ◽

Cited By ~ 28

Author(s):

Ayumu HOSHI ◽

Motoko TAKAHASHI ◽

Junichi FUJII ◽

Theingi MYINT ◽

Hideaki KANETO ◽

...

Keyword(s):

Enzyme Activity ◽

Diabetic Complications ◽

Polyol Pathway ◽

Diabetic Rats ◽

Sorbitol Dehydrogenase ◽

Enzyme Content ◽

Glycated Protein ◽

Liver And Kidney

Sorbitol dehydrogenase (SDH) is involved in the polyol pathway, which plays an important role in the pathogenesis of diabetic complications. We have measured the tissue distributions of SDH mRNA, both the immunoreactive enzyme levels and the enzyme activity. SDH mRNA was especially abundant in liver, kidney and testis. Both the activity and enzyme content are high in liver and kidney but not in testis. The discrepancy between mRNA and immunoreactive enzyme levels and the activity of SDH observed in testis was also seen in livers of streptozotocin-induced diabetic rats. SDH was found to exist in both glycated and non-glycated forms, with larger amounts of the glycated protein in the diabetic liver. Moreover, after incubation of purified enzyme with glucose or fructose, its activity was markedly decreased. These results indicate that glycation causes a decrease in SDH activity in liver under diabetic conditions. The same post-transcriptional event might occur to decrease the activity of SDH in testis in normal animals.

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