A New N-Terminal Blocking Group Involving a Schiff Base in Hemoglobin A<sub>Ic</sub><sup>*</sup>

Holmquist, W. R.; Schroeder, Werner

doi:10.1021/bi00872a002

Cited by 187 publications

(73 citation statements)

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“…It eventually turned out that these Hb fractions resulted from the binding of various adducts to HbA, leading to changes in physicochemical properties of the molecules (e.g., electric charge) which allowed their separation. After many investigations aimed at identifying the bound components [6] , the structures of these different fractions have been progressively discovered, and it was shown in the late 1970s that various sugars or sugar phosphates were able to form these minor hemoglobins, which were incidently glycated hemoglobins [7] . Glucose was unequivocally identified to generate the most abundant HbA 1 fraction HbA 1c , which was shown to be an Amadori product formed by the irreversible binding of glucose to the β -N-terminal valine residues of globin chains, rearranged into 1-deoxy-1-N-valyl-fructose [8 -12] and present in the ring form [13] .…”

Section: The Times Of Pioneers and Discoveriesmentioning

confidence: 99%

“…This process was demonstrated to occur during the 120-day lifespan of the erythrocytes [14] , glycated Hb content being higher in older than in younger red blood cells [15,16] . Although mentioned in 1966 [6] , the intermediary formation of a labile Schiff base (labile HbA 1c , Hb pre-A 1c ) preceding the Amadori rearrangement and the formation of the characteristic keto-amine linkage was formally described in 1981 only [17] .…”

Section: The Times Of Pioneers and Discoveriesmentioning

confidence: 99%

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A history of HbA_1c through Clinical Chemistry and Laboratory Medicine

Gillery¹

2012

Clinical Chemistry and Laboratory Medicine (CCLM)

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HbA 1c was discovered in the late 1960s and its use as marker of glycemic control has gradually increased over the course of the last four decades. Recognized as the gold standard of diabetic survey, this parameter was successfully implemented in clinical practice in the 1970s and 1980s and internationally standardized in the 1990s and 2000s. The use of standardized and well-controlled methods, with well-defined performance criteria, has recently opened new directions for HbA 1c use in patient care, e.g., for diabetes diagnosis. Many reports devoted to HbA 1c have been published in Clinical Chemistry and Laboratory Medicine (CCLM) journal. This review reminds the major steps of HbA 1c history, with a special emphasis on the contribution of CCLM in this field.

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Section: The Times Of Pioneers and Discoveriesmentioning

confidence: 99%

Section: The Times Of Pioneers and Discoveriesmentioning

confidence: 99%

A history of HbA_1c through Clinical Chemistry and Laboratory Medicine

Gillery¹

2012

Clinical Chemistry and Laboratory Medicine (CCLM)

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“…Detection of the minor haemoglobins, HbAlc and HbAl(a+b+o) [4] and their chemical characterization as non-enzymatically glycosylated derivatives of haemoglobin [5][6][7], has added new dimensions to the continuing debate on the role of hyperglycaemia in the complications of diabetes. Thus, measurement of glycosylated haemoglobin provides an objective, retrospective index of glycaemic control [8][9][10][11][12].…”

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confidence: 99%

Non-enzymatic glycosylation and the chronic complications of diabetes: an overview

Kennedy¹,

1984

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“…4): Khatami et al 9) have suggested that its major action is to inhibit the formation of Amadori product by competing with protein for free open-chain glucose. Brownlee et als8 suggest that aminoguanidine acts by blocking reactive carbonyl groups on the ketoamine, hence preventing cross-link formation; the nucleophilic hydrazine group of amino guanidine attacks the electron deficient carbonyl carbon to form a hydrazone-type com pound.…”

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confidence: 99%

The maillard or browning reaction in diabetes

John¹,

Lamb²

1993

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A major pathophysiological consequence of hyperglycae mia is the extensive chemical interaction of glucose with proteins, leading to its attachment to these proteins with out the aid of enzymes. Even though the Maillard reac tions have been of considerable interest to food chemists since the tum of the century,' it has only been relatively recently that attention has focused on non-enzymic glyca tion of proteins in vivo. Although non-enzymic glycation leading to formation of reversible Amadori products acts on many proteins throughout the body, it is less obvious how these products are related to the pathophysiology of diabetic complications. Recent efforts have focused on biologically important further products of the glycation reaction, which are derived slowly from the Amadori product following a sequence of further reactions and rearrangements? These compounds, in contrast to the Amadori product, are formed irreversibly resulting in accumulation on long-lived proteins; these have been called advanced glycation end (AGE) products. BIOCHEMISTRY OF THE EARLY MAILLARD REACTIONThe initial Maillard reaction is the condensation of the free aldehyde group of carbohydrate with either the f-amino group of lysine or hydroxylysine residues or the a-amino group of the N-terminal amino acid of proteins.2 Only open forms of sugars react with proteins, the carbonyl group of an acyclic monosaccharide attaching to a protein amino group via nucleophilic attack to form a labile aldi mine (Schiff base).2 This product may hydrolyse back to glucose and protein or undergo an Amadori rearrange ment to form a l-amino-I-deoxyfructose (fructosamine) derivative by a stable, though slightly reversible, keto amine linkage (Fig. 1). This product can cyclise to a ring structure (N-substituted-I-amino-deoxyketopyranose ).2The rate of the Amadori rearrangement is approximately one-sixtieth that of the dissociation to glucose and protein3 and also varies between proteins: for example, the Ama- dori rearrangement occurs about five times more rapidly in albumin than in haemoglobin.4 The labile Schiff base form can also exist as a cyclic glucose adduct (N-substituted aldosylamine) and in vivo proteins will exist predom inantly in the cyclic form of both the Schiff base and the Amadori product, although the labile form is probably lost in most purification procedures.4Glycation of haemoglobin is somewhat atypical, as this reaction occurs predominantly between glucose and the N-terminal valine of the �-chain of haemoglobin to form HbA,/ on other proteins glucose adducts are found on lysine and hydroxylysine residues.2 A variety of other aldose and ketose sugars, including glucose-6-phosphate, galactose, mannose, ribose, fructose and xylulose, can participate in the glycation reaction.6 The relative reactiv ity varies up to 300-fold between monosaccharides and depends largely on the equilibrium between the reactive open (carbonyl) and closed (hemiacetal) configurations of the sugar. Aldose sugars react more rapidly than ketose sugars since the aldeh...

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A New N-Terminal Blocking Group Involving a Schiff Base in Hemoglobin A_Ic^*

Cited by 187 publications

References 50 publications

A history of HbA_1c through Clinical Chemistry and Laboratory Medicine

A history of HbA_1c through Clinical Chemistry and Laboratory Medicine

Non-enzymatic glycosylation and the chronic complications of diabetes: an overview

The maillard or browning reaction in diabetes

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A New N-Terminal Blocking Group Involving a Schiff Base in Hemoglobin AIc*

Cited by 187 publications

References 50 publications

A history of HbA1c through Clinical Chemistry and Laboratory Medicine

A history of HbA1c through Clinical Chemistry and Laboratory Medicine

Non-enzymatic glycosylation and the chronic complications of diabetes: an overview

The maillard or browning reaction in diabetes

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Product

Resources

About

A New N-Terminal Blocking Group Involving a Schiff Base in Hemoglobin A_Ic^*

A history of HbA_1c through Clinical Chemistry and Laboratory Medicine

A history of HbA_1c through Clinical Chemistry and Laboratory Medicine