Amino acid sequence of the human haptoglobin β chain. I. Amino- and carboxyl-terminal sequences

Barnett, Don R.; Lee, Tong-Ho; Bowman, Barbara H.

doi:10.1021/bi00757a012

Cited by 36 publications

(6 citation statements)

References 22 publications

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“…Binding of Hb af3 subunits is reported to occur on the ,B chain of Hp (18). Partial amino acid sequence analysis of the haptoglobin 3 polypeptide (hp ,B) chain indicated it to be chemically similar to the chymotrypsinogen family of serine proteases (19,20). This suggests that Hp is evolutionarily related to the serine proteases as a result of gene duplication of a serine protease gene (or a precursor thereof) and subsequent divergence to its present structure.…”

mentioning

confidence: 99%

Covalent structure of human haptoglobin: a serine protease homolog.

Kurosky¹,

Barnett²,

Lee³

et al. 1980

Proc. Natl. Acad. Sci. U.S.A.

231

132

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The complete amino acid sequences and the disulfide arrangements of the two chains of human haptoglobin 1-1 were established. The al and P chains of haptoglobin contain 83 and 245 residues, respectively. Comparison of the primary structure of haptoglobin with that of the chymotrypsinogen family of serine proteases revealed a significant degree of chemical similarity. ITe probability was less than 10-5 that the chemical similarity of the P chain of haptoglobin to the proteases was due to chance. The amino acid sequence of the P chain of haptoglobin is 29-33% identical to bovine trypsin, bovine chymotrypsin, porcine elastase, human thrombin, or human plasmin. Comparison of haptoglobin al chain to activation peptide regions of the zymogens revealed an identity of 25% to the fifth "kringle" region of the activation peptide of plasminogen. The probability was less than 0.014 that this similarity was due to chance. These results strongly indicate haptoglo in to be a homolog of the chymotrypsinogen family of serine proteases. Alignment of the ,Bchain sequence of haptoglobin to the serine proteases is remarkably consistent except for an insertion of 16 residues in the region corresponding to the methionyl loop of the serine proteases. The active-site residues typical of the serine proteases,-histidine-57 and serine-195, are replaced in haptoglobin by lysine and alanine, respectively; however, aspartic acid-102 and the trypsin specificity residue, aspartic acid-189, do occur in haptoglobin. Haptoglobin and the serine proteases represent a striking example of homologous proteins with different biological functions.

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mentioning

confidence: 99%

Covalent structure of human haptoglobin: a serine protease homolog.

Kurosky¹,

Barnett²,

Lee³

et al. 1980

Proc. Natl. Acad. Sci. U.S.A.

231

132

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“…Characterization of the cyanogen bromide fragments of the (3 chain of human haptoglobin presented here is consistent with a composition of 4 methionyl residues and 5 CNBr fragments per molecule. Previous preliminary evidence (Barnett et al, 1972) indicated 6 cyanogen bromide fragments in the hp 3 chain; however, no evidence for the 6th fragment was 22Pth residues quantitated by amino acid analysis after HI hydrolysis, except those marked with asterisk which were quantitated by gas chromatography. Results given are for a single analysis; however, except for CNBr I, analysis of fragments and 0 chain were repeated two to five times on different preparations.…”

Section: Discussionmentioning

confidence: 86%

“…Amino-Terminal Sequence Analysis. Automated sequence analysis of 36 residues of the intact hp 0 chain was previously reported by Barnett et al (1972). These sequence data were obtained from tryptic and chymotryptic peptides, from sequencer analysis of intact hp 0 chain, and from preliminary sequencer analysis of CNBr II, and indicated that residues 2-9 were reiterated at positions 20-27.…”

Section: Purification Of Haptoglobinmentioning

confidence: 95%

“…*/Established by time-course hydrolysis (see Figure 6). ® Determined by Barnett et al (1972) (see Discussion).…”

Section: Purification Of Haptoglobinmentioning

confidence: 99%

“…Some sequence similarity between the a chain of haptoglobin and immunoglobulin light chains was presented to support this comparison (Black and Dixon, 1968). Sequence studies of the 8 chain, however, revealed considerable similarity to the chymotrypsin family of serine proteases (Barnett et al, 1970(Barnett et al, , 1972Kurosky et al, 1974a,b).…”

mentioning

confidence: 94%

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Characterization of the cyanogen bromide fragments of the β chain of human haptoglobin

Kurosky¹,

Hay²,

Kim³

et al. 1976

Biochemistry

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Characterization of the cyanogen bromide (CNBr) fragments of the beta chain of human haptoglobin revealed five major fragments resulting from cleavage of four methionyl residues. The fragments were isolated by gel filtration in guanidine-HCl on Sepharose 6B and Bio-Gel P10 and P60. Compositional analyses of the five cyanogen bromide fragments accounted for 248-253 amino acid residues in agreement with the number of residues determined for the intact beta chain. Most of the carbohydrate was attached to CNBr II. Automated amino-terminal sequence analysis and carboxyl-terminal hydrolysis with carboxypeptidase of the haptoglobin beta chain and cyanogen bromide fragments identified 139 residues, or about 55% of the beta-chain molecule. The placement of the fragments within the beta-chain molecule was established by sequence analysis of whole beta chain and a plasmin cleavage fragment. The position of CNBr V was confirmed by the absence of homoserine or homoserine lactone. Cyanogen bromide reaction of intact haptoglobin 1-1 resulted in the isolation of a beta-chain fragment, CNBr III, covalently attached to the intact alpha1 chain by a single disulfide bond. The beta chain was shown to have primary structural similarities to the chymotrypsin family of serin eproteases. Partial sequence analysis of CNBr V established the region which is comparable to the serine-195 active-site region: /Asp-Thr-Cys-Tyr-Gly-Asp-Ala-Gly-Ser-Ala-Phe/ (residues 189-199, chymotrypsinogen A numbering). The active-site serine-195 is replaced by alanine; however, the specificity residue of the trypsin-like enzymes, Asp-189, is preserved. Several minor cyanogen bromide cleavage products were also identified in yields of up to 15%. These minor cleavage products give evidence that tryptophanyl residues in proteins, or glycoproteins, are also susceptible to cyanogen bromide cleavage.

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Chemie und Bedeutung des Kohlenhydrat‐Anteils menschlicher Serum‐Glykoproteine

Heide

Schwick

1973

Angewandte Chemie

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Die Glykoproteine üben als Transportproteine, Inhibitoren, Enzyme, Hormone, Komplementfaktoren und Immunglobuline wichtige biologische Funktionen aus. Ihre Chemie ist durch einige Regeln gekennzeichnet. So können nur Asparagin, Threonin oder Serin die Oligosaccharid‐Gruppen tragen; bei der N‐Acylglykosylamin‐Bindung unter Beteiligung von Asparagin liegt in der Peptidkette stets die Gruppierung Asn‐X‐Thr oder Asn‐X‐Ser vor. Beim Molekulargewicht der Glykoproteine. ihrem Kohlenhydrat‐Gehalt und den relativen Anteilen der einzelnen Zucker findet man allerdings kaum Übereinstimmungen. Die biologische Bedeutung des Kohlenhydrat‐Anteils ist noch ungeklärt, doch zeichnet sich eine Vorstellung von der Rolle der leicht entfernbaren Neuraminsäure ab.

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Amino acid sequence of the human haptoglobin β chain. I. Amino- and carboxyl-terminal sequences

Cited by 36 publications

References 22 publications

Covalent structure of human haptoglobin: a serine protease homolog.

Covalent structure of human haptoglobin: a serine protease homolog.

Characterization of the cyanogen bromide fragments of the β chain of human haptoglobin

Chemie und Bedeutung des Kohlenhydrat‐Anteils menschlicher Serum‐Glykoproteine

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