Amino acid sequences of two glycopeptides isolated from tryptic and chymotryptic hydrolysates of human lactotransferrin

Spik, Geneviève; Vandersyppe, Renée; Montreuil, Jean

doi:10.1016/0014-5793(74)80116-x

Cited by 17 publications

(6 citation statements)

References 11 publications

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“…The amino acid sequences of both peptide chains were previously described [10,40]. The more complex glycopeptides F and G represent a mixture of glycopeptides possessing the two types of peptide chain.…”

Section: Isolation and Characteristics Of The Glycopeptidesmentioning

confidence: 99%

Primary Structure of the Glycans from Human Lactotransferrin

Spik

Strecker

Fournet

et al. 1982

European Journal of Biochemistry

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The polypeptide chain of human lactotransferrin possesses two glycosylation sites to which glycans are linked through an N-(P-asparty1)-N-acetylglucosaminylamine bond and which are structurally heterogenous. After chymotryptic or pronase digestions, glycopeptides with five different glycan structures could be isolated. For three of them, the structure has been determined by the application of methanolysis, methylation analysis, hydrazinolysis/nitrous deamination, enzymatic cleavage and 'H-NMR spectroscopy at 360 MHz: Glycopeptides A and B : NeuAc(cr2-6)Gal(~1-4)GlcNAc(~l-2)Man(crl-3) shows that important differences exist between the number and the structure of the glycans present in these four kinds of transferrins.In the case of human lactotransferrin, in 1966, the presence of two glycans linked by a 4-N-(2-acetamido-2-deoxy-B-~-glucopyranosy1)-L-asparagine linkage was described as well as one 0-glycosidically-linked glycan [17]. The presence of two N-glycosidically-linked glycans was confirmed in 1973 and for one of them the structure was proposed [18].Microheterogeneity of the carbohydrate moieties was later demonstrated and partial results concerning different glycan structures were given in general reviews [19-211. In the present paper we describe the complete primary structure of three types of glycans as determined by methanolysis, methylation analysis, hydrazinolysis/nitrous deamination, mass spectrometry, enzymatic cleavage and 'H-NMR spectroscopy at [111._.___

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Section: Isolation and Characteristics Of The Glycopeptidesmentioning

confidence: 99%

Primary Structure of the Glycans from Human Lactotransferrin

Spik

Strecker

Fournet

et al. 1982

European Journal of Biochemistry

Self Cite

199

114

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“…The present results allowed a series of comparisons to be made with human serum transferrin and hen ovotransferrin. Several years ago, short cysteic-acid containing peptides [34] and short tryptic or chymotryptic glycopeptides [35] of human lactotransferrin have been described: some of the reported results could not be corroborated later. More recently, the N-terminal sequence [36] and studies concerning two glycopeptides [37] have been published.…”

mentioning

confidence: 98%

“…Like all transferrins, lactotransferrin possesses two metalbinding sites each of which can bind a ferric ion (Fe3+) together with a bicarbonate anion. The subdivision of the transferrin molecules into two lobes, each associated with one metal-binding site, has been demonstrated by sequence studies [20 ~ 251, limited proteolysis of a number of transferrin species variants [26-311 and results of low-resolution X-ray crystallographic studies [32, 331. Several years ago, short cysteic-acid containing peptides [34] and short tryptic or chymotryptic glycopeptides [35] of human lactotransferrin have been described: some of the reported results could not be corroborated later. More recently, the N-terminal sequence [36] and studies concerning two glycopeptides [37] have been published.…”

mentioning

confidence: 98%

Human lactotransferrin: amino acid sequence and structural comparisons with other transferrins

et al. 1984

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The complete amino acid sequence (703 amino acid residues) of human lactotransferrin has been determined. The location of the disulfide bridges has also been investigated. Computer analysis established internal homology of the two domains (residues 1 -338 and residues 339 -703). Each domain contains a single iron-binding site and a single glycosylation site (asparagine residues 137 and 490) located in homologous positions. Prediction of the secondary structure of the two homologous moieties of human lactotransferrin has also been performed. The present results allowed a series of comparisons to be made with human serum transferrin and hen ovotransferrin. Several years ago, short cysteic-acid containing peptides [34] and short tryptic or chymotryptic glycopeptides [35] of human lactotransferrin have been described: some of the reported results could not be corroborated later. More recently, the N-terminal sequence [36] and studies concerning two glycopeptides [37] have been published. In a previous series of investigations, we reported the cleavage of the lactotransferrin molecule with cyanogen bromide (CNBr) [38]. In 1981, seven fragments were characterized and aligned (FI, FII, FIII, FIV, FV', FVI and FVII) [21]. Only four fragments (FIII, FIV, FVI and FV') have so far been sequenced [21, 391.

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“…Table 3. Carbohydrate sequence proposed for human lactotransferrin (Spik et al 1974;Montreuil, 1975) ot-2,6 £-1,4…”

Section: Evolution Of the Sugar Part As A Function Of Developmentmentioning

confidence: 99%

“…The glycoprotein, lactotransferrin, has a mol. wt of 76 500 and consists of a single polypeptide chain to which 2 carbohydrate groups are attached (Spik et al 1974;Montreuil, 1975). We are currently studying the amino acid structure of this glycoprotein (Jolles et al 1976) in order, first, to localize the 2 glycans and the 2 iron binding sites on the polypeptide chain, and second, to compare the structures of serum, lacto-and other transferrins.…”

Section: Bole Of the Sugars In K-caseinmentioning

confidence: 99%

The carbohydrate portions of milk glycoproteins

Joliés

1979

Journal of Dairy Research

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SUMMARYk-Casein is the main glycoprotein of cow's milk. Its polysaccharide part is O-glycosidically linked to threonine residue 133. It contains only 3 different sugars (Gal, GalNAc, NeuNAc), but a microheterogeneity has been detected at the sugar level. Two main polysaccharides have so far been characterized. The structure of the trisaccharide is NeuNAc α → 3 Gal β1 →3 GalNAc; the tetrasaccharide contains one additional sialic acid. The polysaccharide part of ovine k-casein resembles that of bovine k-casein, but contains also N-glycolyl neuraminic acid. Human k-casein contains 3 times more carbohydrate than bovine k-casein with 2 additional sugars, GlcNAc and Fuc. The various polysaccharide parts isolated from bovine colostrum k-caseinoglycopeptide are much more complex than those obtained from the normal glycopeptide, indicating an evolution of the sugar part as a function of time after parturition. Some aspects of the secondary structure of k-casein and the role of the sugar part are discussed. The carbohydrate moiety of another milk protein, human lactotransferrin, is also discussed briefly. It is comprised of 2 identical glycan groups, N-glycosidically linked to the protein, and quite different from the k-casein carbohydrate moiety.

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Amino acid sequences of two glycopeptides isolated from tryptic and chymotryptic hydrolysates of human lactotransferrin

Cited by 17 publications

References 11 publications

Primary Structure of the Glycans from Human Lactotransferrin

Primary Structure of the Glycans from Human Lactotransferrin

Human lactotransferrin: amino acid sequence and structural comparisons with other transferrins

The carbohydrate portions of milk glycoproteins

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