Comparison of modification sites formed on human serum albumin at various stages of glycation

Omar S. Barnaby, Ronald L. Cerny, William Clarke, David S. Hage

Research output: Contribution to journalArticle

Abstract

Background: Many of the complications encountered during diabetes can be linked to the non-enzymatic glycation of proteins, including human serum albumin (HSA). However, there is little information regarding how the glycation pattern of HSA changes as the total extent of glycation is varied. The goal of this study was to identify and conduct a semi-quantitative comparison of the glycation products on HSA that are produced in the presence of various levels of glycation. Methods: Three glycated HSA samples were prepared in vitro by incubating physiological concentrations of HSA with 15. mmol/l glucose for 2 or 5. weeks, or with 30. mmol/l glucose for 4. weeks. These samples were then digested and examined by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) to identify the glycation products that were formed. Results: It was found that the glycation pattern of HSA changed with its overall extent of total glycation. Many modifications including previously-reported primary glycation sites (e.g., K199, K281, and the N-terminus) were consistently found in the tested samples. Lysines 199 and 281, as well as arginine 428, contained the most consistently identified and abundant glycation products. Lysines 93, 276, 286, 414, 439, and 524/525, as well as the N-terminus and arginines 98, 197, and 521, were also found to be modified at various degrees of HSA glycation. Conclusions: The glycation pattern of HSA was found to vary with different levels of total glycation and included modifications at the 2 major drug binding sites on this protein. This result suggests that different modified forms of HSA, both in terms of the total extent of glycation and glycation pattern, may be found at various stages of diabetes. The clinical implication of these results is that the binding of HSA to some drug may be altered at various stages of diabetes as the extent of glycation and types of modifications in this protein are varied.

Original languageEnglish (US)
Pages (from-to)277-285
Number of pages9
JournalClinica Chimica Acta
Volume412
Issue number3-4
DOIs
StatePublished - Jan 30 2011

Fingerprint

Serum Albumin
Medical problems
Lysine
Arginine
Glucose
Proteins
Pharmaceutical Preparations
Ionization
Mass spectrometry
Desorption
Mass Spectrometry
Lasers
Binding Sites

Keywords

  • Diabetes
  • Glycation-related modifications
  • Human serum albumin
  • Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry
  • Non-enzymatic glycation

ASJC Scopus subject areas

  • Biochemistry
  • Clinical Biochemistry
  • Biochemistry, medical

Cite this

Comparison of modification sites formed on human serum albumin at various stages of glycation. / Barnaby, Omar S.; Cerny, Ronald L.; Clarke, William; Hage, David S.

In: Clinica Chimica Acta, Vol. 412, No. 3-4, 30.01.2011, p. 277-285.

Research output: Contribution to journalArticle

Barnaby, Omar S. ; Cerny, Ronald L. ; Clarke, William ; Hage, David S. / Comparison of modification sites formed on human serum albumin at various stages of glycation. In: Clinica Chimica Acta. 2011 ; Vol. 412, No. 3-4. pp. 277-285.
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abstract = "Background: Many of the complications encountered during diabetes can be linked to the non-enzymatic glycation of proteins, including human serum albumin (HSA). However, there is little information regarding how the glycation pattern of HSA changes as the total extent of glycation is varied. The goal of this study was to identify and conduct a semi-quantitative comparison of the glycation products on HSA that are produced in the presence of various levels of glycation. Methods: Three glycated HSA samples were prepared in vitro by incubating physiological concentrations of HSA with 15. mmol/l glucose for 2 or 5. weeks, or with 30. mmol/l glucose for 4. weeks. These samples were then digested and examined by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) to identify the glycation products that were formed. Results: It was found that the glycation pattern of HSA changed with its overall extent of total glycation. Many modifications including previously-reported primary glycation sites (e.g., K199, K281, and the N-terminus) were consistently found in the tested samples. Lysines 199 and 281, as well as arginine 428, contained the most consistently identified and abundant glycation products. Lysines 93, 276, 286, 414, 439, and 524/525, as well as the N-terminus and arginines 98, 197, and 521, were also found to be modified at various degrees of HSA glycation. Conclusions: The glycation pattern of HSA was found to vary with different levels of total glycation and included modifications at the 2 major drug binding sites on this protein. This result suggests that different modified forms of HSA, both in terms of the total extent of glycation and glycation pattern, may be found at various stages of diabetes. The clinical implication of these results is that the binding of HSA to some drug may be altered at various stages of diabetes as the extent of glycation and types of modifications in this protein are varied.",
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AB - Background: Many of the complications encountered during diabetes can be linked to the non-enzymatic glycation of proteins, including human serum albumin (HSA). However, there is little information regarding how the glycation pattern of HSA changes as the total extent of glycation is varied. The goal of this study was to identify and conduct a semi-quantitative comparison of the glycation products on HSA that are produced in the presence of various levels of glycation. Methods: Three glycated HSA samples were prepared in vitro by incubating physiological concentrations of HSA with 15. mmol/l glucose for 2 or 5. weeks, or with 30. mmol/l glucose for 4. weeks. These samples were then digested and examined by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) to identify the glycation products that were formed. Results: It was found that the glycation pattern of HSA changed with its overall extent of total glycation. Many modifications including previously-reported primary glycation sites (e.g., K199, K281, and the N-terminus) were consistently found in the tested samples. Lysines 199 and 281, as well as arginine 428, contained the most consistently identified and abundant glycation products. Lysines 93, 276, 286, 414, 439, and 524/525, as well as the N-terminus and arginines 98, 197, and 521, were also found to be modified at various degrees of HSA glycation. Conclusions: The glycation pattern of HSA was found to vary with different levels of total glycation and included modifications at the 2 major drug binding sites on this protein. This result suggests that different modified forms of HSA, both in terms of the total extent of glycation and glycation pattern, may be found at various stages of diabetes. The clinical implication of these results is that the binding of HSA to some drug may be altered at various stages of diabetes as the extent of glycation and types of modifications in this protein are varied.

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KW - Non-enzymatic glycation

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