Chromatographic Isolation and Partial Characterization of Reduced κ-Casein Components<sup>*</sup>

Woychik, J.H.; Kalan, Edwin B.; Noelken, Milton E.

doi:10.1021/bi00871a016

Cited by 66 publications

(25 citation statements)

References 26 publications

(31 reference statements)

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“…La composition en acides aminhs de la caskine xB: Asp,, Asn,, Thr,,, Ser,,, SerP,, Glu,,, Gln,,, PyroGlu,, Pro,,, Gly,, Ala,,, Val,,, ' / , Cys,, Met,, I h 3 , Leu,, Tyr,, Phe,, Lys,, His3, Trp,, b g , , dbduite de la sbquence, est trks proche de celle que nous avons calcul6e en faisant la somme des diEhrents rhsidus d'acides aminbs constitutifs des 3 peptides oCNBro de la cashine xB, [l] et de celles rapportbes antbrieurement par divers auteurs [26,27].…”

Section: Discussionunclassified

“…Si l'on se r6fkre aux acides aminits basiques par exemple, seules diffkrent les estimations du nombre de rhsidus lysyle qui serait itgal B 6 ou 7. En fait, le premier chiffre parait le plus correct, car il correspond exactement B la diff'brence entre les valeurs de 9 et 3 trouvees pour la lysine, respectivement dans la casbine x [26,27,1] et le caseinomacropeptide [i, 25,28-321.…”

Section: Ri~sultatsunclassified

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Structure primaire de la caséine κB bovine

Mercier¹,

Brignon²,

Ribadeau‐Dumas³

1973

European Journal of Biochemistry

255

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In a previous report [1], we have given the complete primary structure of ϰB1‐caseinomacro‐peptide which is the soluble COOH‐terminal fragment split from bovine ϰB1‐casein by rennin. We also reported on the COOH‐terminal sequence of the NH2‐terminal fragment, the so‐called para‐ϰ‐casein. The present paper deals with the complete amino acid sequence of bovine ϰB‐casein, which has now been achieved by establishing the primary structure of para‐ϰB‐casein of which we discuss the salient features. This work has been reported briefly in a short communication [2]. SCM‐para‐ϰB‐casein and maleyl ϰBCN1, the NH2‐terminal cyanogen bromide fragment of ϰB‐casein [1], were used as starting material. The tryptic and peptic peptides of SCM‐para‐ϰB‐casein and the chymotryptic peptides of ϰBCN1 were isolated on Dowex 50 and Sephadex G‐50 or G‐25, and their sequences were determined either partially or completely by using classical methods and in some cases mass spectrometry. All these peptides and a NBS fragment of SCM‐para‐ϰB‐casein have provided all the overlaps needed for the completion of the amino acid sequence of para‐ϰB‐casein. Para‐ϰB‐casein is a single polypeptide chain containing 105 amino acid residues: Asp3, Asn4, Thr3, Ser7, PyroGlu1, Glu4, Gln12, Pro12, Gly1, Ala9, Val5, 1/2 Cys2, Met1, Ile6, Leu7, Tyr9, Phe4, Lys6, His3, Trp1, Arg5, and its molecular weight has been calculated to be 12269. The average hydrophobicity, calculated according to Bigelow [3], is 5.48 kJ (1.310 kcal) per residue, and para‐ϰB‐casein can be therefore considered to be a very hydrophobic molecule. Its net positive charge at pH of native milk (about 6.8) is very close to 4.5. The high content (11.5%) and rather uniform distribution of prolyl residues are incompatible with much α‐helical organization of the molecule, as previously shown for ϰ‐casein [4]. Both hydrophobic and charged amino acid residues are distributed non‐uniformly along the chain. Two regions, 1–24 and 80–105, are hydrophilic: the very hydrophilic former, with NH2‐terminal pyroglutamic acid, contains a cysteinyl residue located inside a cluster of eleven ionizable residues including six out of the seven total dicarboxylic amino acids; the 80–105 region, which contains the second cysteinyl residue in position 88, is rather hydrophilic, except at the COOH‐terminal end which is hydrophobic in spite of the presence of a cluster of four basic residues. These two hydrophilic regions are very likely to be on the outisde of the molecule and this may favor the formation of intermolecular S‐S bonds. The very hydro‐phobic central part of the chain, viz., 25–79, where most of the aromatic residues are located, has a para‐ϰ‐casein‐like behaviour in aqueous solution, and it may be responsible for the aggregation ability of para‐ϰ‐casein. According to the sequence data of both ϰB1‐caseinomacropeptide [1] and para‐ϰ‐casein, it is concluded that bovine ϰB‐casein is made up of a single polypeptide chain containing 169 amino acid residues: Asp4, Asn7, Thr14, Ser12, SerP1, PyroGlu1, Glu12, Gln14, P...

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Section: Discussionunclassified

Section: Ri~sultatsunclassified

Structure primaire de la caséine κB bovine

Mercier¹,

Brignon²,

Ribadeau‐Dumas³

1973

European Journal of Biochemistry

255

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“…Because of its amphipathic character, κ-casein forms aggregates in solution, similar to β-casein [Vreeman (1979)], but polymers ranging from dimers to octamers and higher polymers may also arise as a result of the formation of intermolecular disulphide bonds [Woychik et al (1966); Groves et al (1992)]. However, unlike the hydrophobically bound β-casein aggregates, κ-casein aggregates cannot be dissociated simply by reducing the temperature or ionic strength but require some disulphide bond breaking agent such as mercaptoethanol; when this occurs, the reduced κ-casein behaves rather like β-casein [Dalgleish (1992)].…”

Section: κ-Caseinmentioning

confidence: 99%

Casein Proteins

Singh

2016

Biomaterials From Nature for Advanced Devices and Therapies

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“…To the reduced Kcasein solution, 40 g of solid urea was added. K-Casein was fractionated into subcomponents fundamentally according to the method of Woychik et al 9 ) The solution was put on a column of DEAE-cellulose (DE-52, Whatman) preequilibrated with 10 mM imidazole-HCI buff~, pH 7.0, containing 20 mM 2-mercaptoethanol and 4 M urea (buffer I). Isocyanate was removed previously by passing the buffer through a thin layer of DE-52.…”

mentioning

confidence: 99%