The inter‐chain disulfide bonds of a μ‐chain disease protein

Mihaesco, Edith; Mihaesco, Constantin

doi:10.1016/0014-5793(74)81026-4

Cited by 4 publications

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“…The mild reduction of proteins BOT, SCO and CO was performed as described previously [5]. In order to differentiate the peptides containing half-cystines involved in interchain disulfide bridges from those derived from intrachain disulfide bridges in protein BOT, we used a double radiolabelling method.…”

Section: Reduction and Curhoxymethylutionmentioning

confidence: 99%

The Primary Structure of the Constant Part of μ‐Chain‐Disease Protein BOT

Mihaesco

Barnikol-Watanabe

Barnikol

et al. 1980

European Journal of Biochemistry

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The complete primary structure of the constant part of the p-chain-disease protein, BOT, was established. It includes the whole CH2, CH3 and CH4 domains. Two amino acid changes were found, at positions 309 (Ser -+ Gly) and 333 (Val ---f Gly) (GAL numbering). In two additional monoclonal p chains (SCO and CO), the same positions showed an amino acid variability. From these data it may be concluded that four types of p chains exist in the human: (1) GAL type with Ser-309 and Val-333; (2) OU type with Gly-309 and Val-333; (3) SCO type with Ser-309 and Gly-333; (4) BOTjCO type with Gly-309 and Gly-333. The meaning of this molecular polymorphism is discussed.The complete primary structure of the human IgM molecules is now established for two monoclonal proteins GAL and OU [l, 21. The amino acid sequence of their constant parts are essentially the same. The only exception was a residue change at position 309, serine in protein GAL compared to glycine in protein OU. The sequence determination of the Fc regions of four additional monoclonal IgM proteins [3] as well as the (Fc)Sp fragment of a pool of normal polyclonal IgM [4] suggested a lack of variability of the constant part of the human p chain. During the studies made by two of us on the covalent structure of a deleted p-chain protein (BOT) [5], we have described a limited number of amino acid changes restricted to the constant region as compared with the known reference p-chain sequences. Protein BOT is a p-chaindisease protein, which lacks light chains and consists of incomplete heavy chains. The p-chain disease appears to be relatively rare : 15 cases have been reported since its first description [6] in contrast with the 50 y-heavychain diseases and the 150 a-chain diseases presently known to us [7]. Only scare structural data are available on p-chain-disease proteins (GLI, BUR, BOT) [X-lo]. Our present work had two aims: first, to establish the precise amino acid sequence of protein BOT and to look for its homology to those of the presently known complete p chains (GAL and OU) ; second, to examine several monoclonal human IgMs in order to find out if the constant domains of Our results show that the structural homology of protein BOT implicates the CH2, CH3 and CH4 domains. However, in the two positions (309 and 333) different amino acid residues were found in contrast to p-chain GAL: 309 = Ser -+ Gly and 333 = Val + Gly. We also present the amino acids found at the same position in two other monoclonal p chains (SCO and CO). MATERIALS AND METHODS ProteinsThe isolation and purification of protein BOT was previously described [lo]. The proteins SCO and CO are monoclonal IgM from patients with Waldenstrom's macroglobulinemia. The methods used for their isolation and purification were : (a) gel filtration chromatography on Sepharose 6B in 0.1 M Tris/HCl pH 8.0, 1 M NaCl; (b) zone electrophoresis of the 19-S peak on a Pevikon block. Reduction and CurhoxymethylutionThe mild reduction of proteins BOT, SCO and CO was performed as described previously [5]. In order to...

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Section: Reduction and Curhoxymethylutionmentioning

confidence: 99%