β-Lactoglobulins

McKenzie, H.A.

doi:10.1016/b978-0-12-485202-0.50013-0

Cited by 110 publications

(55 citation statements)

References 161 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Electrophoresis of 'whey' protein fractions was carried out on gels 1· 5 mm thick by the method described by McKenzie (1971).…”

Section: Electrophoresismentioning

confidence: 99%

Bovine ß-Lactoglobulin E, F and G of Bali (Banteng) Cattle, Bos (Bihos) Javanicus

Bell¹,

Ha²,

Dc³

1981

Aust. Jnl. Of Bio. Sci.

View full text Add to dashboard Cite

An electrophoretic examination is made of samples of milk from eight Bali (banteng) cattle, Bos (Bibos) javanicus, in the Northern Territory of Australia. There are two new electrophoretically distinct bovine ft-Iactoglobulins, designated E and F, present in these samples. It is shown by amino acid analysis and tryptic peptide mapping of isolated samples that: (I) both E and F differ from the B variant of domestic cattle (Bos taurus) by + 1 G1y, -1 Glu at residue 157 or 158; and (2) the F variant has the additional charge differences from E and B due to + I Tyr, -1 Asp at residue 129 or 130. It is also shown by studies of peptides produced by the action of Staphylococcus aureus strain V8 protease and by more recent amino acid analyses that (1) the GlyjGlu substitution is at residue 158; (2) there is an additional Bali variant, designated ft-lactoglobulin G, differing from E by + 1 Met, -1 lie at residue 78, but having the same mobility as E; and (3) there is an hitherto undetected neutral residue substitution of + 1 Ser, -1 Pro at position 50 in the F variant. The relation of these variants to other known ft-lactoglobulin variants of the Bos genus is discussed.

show abstract

“…Electrophoresis of 'whey' protein fractions was carried out on gels 1· 5 mm thick by the method described by McKenzie (1971).…”

Section: Electrophoresismentioning

confidence: 99%

Bovine ß-Lactoglobulin E, F and G of Bali (Banteng) Cattle, Bos (Bihos) Javanicus

Bell¹,

Ha²,

Dc³

1981

Aust. Jnl. Of Bio. Sci.

View full text Add to dashboard Cite

show abstract

“…6-6 ±0-4 12-0±l-l 15-6 + 1-2 is known to undergo irreversible thermodenaturation due to aggregation involving sulphur groups, followed by nonspecific aggregation (Sawyer, 1968;McKenzie, 1971). The complex pathway for the heat denaturation of this protein might explain the strong dependence of the denaturation temperature and sharpness of the denaturation peak on heating rate and pH.…”

Section: Fi-lactoglobulinmentioning

confidence: 99%

“…The following optical factors (El^) and mol. wts were used: /?-lg, 9-3 at 278 nm,18422 (McKenzie, 1971); a-la, 20-6 at 280 nm (Quarfoth & Jenness, 1975), 14176 (Brew, Vanaman & Hill, 1967, corrected by Gordon, 1971; bovine serum albumin, 6-67 at 279 nm (Aoki et al 1973), 66000 (Spahr & Edsall, 1964; lactoferrin, 12-7 (apo form) and 15-7 (Fe saturated form) at 280 nm (Brown & Parry, 1974), 93000 (Weiner & Szuchet, 1975); ribonuclease-A, 7-38 at 278 nm (Scott & Scheraga, 1963), 13683 (Hirs, Moore & Stein, 1956); lysozyme, 26-3 at 281 nm, 14400 (Sophianopoulos et al 1962); a chymotrypsin, 20-3 at 280 nm (Aune & Timaslieff, 1971), 25200 (Privalov & Khechinashvili, 1974);y-globulin, 13-5 at 275 nm, 156000 (Sober, 1968). y-Globulin contains various types of immunoglobulins (Ig), e.g.…”

Section: Solutionsmentioning

confidence: 99%

A calorimetric study of the thermal denaturation of whey proteins in simulated milk ultrafiltrate

Rüegg

Moor

Blanc

1977

Journal of Dairy Research

234

106

View full text Add to dashboard Cite

SUMMARY. Differential scanning calorimetry (DSC) was used to study thermal transitions of the following whey proteins and enzymes in milk ultrafiltrate solution: /Mactoglobulin, a-lactalbumin, serum albumin, y-globulin, apo-and Fe-lactoferrin, lysozyme, ribonuclease, a-chymotrypsin and xanthine oxidase. Denaturation enthalpies (A-Ho), denaturation temperatures (T D ) and the half width of the denaturation peaks in DSC thermograms (A? 1 !)) were determined and the degree of renaturation was estimated by rescanning previously denatured samples. A fair correlation between the results obtained by DSC and other more classical methods was found in general. However, for some proteins (a-lactalbumin, lysozyme, ribonuclease and xanthine oxidase), which have so far been considered relatively thermostable, calorimetry reveals conformational changes starting at temperatures as low as about 45 °C. In these cases thermostability observed after heat treatment of milk should be interpreted in terms of renaturation and not of high temperatures of denaturation.Calorimetric techniques have been found useful for studying the effect of heat on proteins in aqueous solutions (Privalov, 1974; Sturtevant, 1974). The published calorimetric investigations of protein denaturation, however, either do not include milk proteins or were not carried out in solutions resembling the natural milk medium. It was thus considered useful to examine the thermal transitions of milk proteins in milk ultrafiltrate by differential scanning calorimetry (DSC). This should give some insight into the structure and stability of proteins in milk as well as the changes in the properties of milk and milk products during heat treatment.The present communication summarizes the results of a calorimetric investigation of the heat-induced transitions and reactions observed in milk ultrafiltrate of the following proteins: /

show abstract

“…These variants of bovine BLG have different self-association properties~Hill et al, 1996!. Variant A forms dimers and then octamers under increasingly acidic conditions, whereas variants B and C do not form octamers~Timasheff & Townend, 1961;Timasheff, 1964;Pessen et al, 1985!, but do form dimers, with dissociation constants in the micromolar range at pH ; 7 and stability constants in the order C Ͼ Ͼ B Ͼ A~Timasheff & Townend, 1961;McKenzie, 1971;McKenzie & Sawyer, 1972;Thresher et al, 1994;Hill et al, 1996;Thresher & Hill, 1997!. Both bovine BLG variants A and B undergo pH-dependent conformational changes in the range pH 6.5 to pH 7.5, the so called N ? R or Tanford transition~Tanford et al, 1959;Hambling et al, 1994!.…”

mentioning

confidence: 99%

Functional implications of structural differences between variants A and B of bovine β‐lactoglobulin

Qin

Bewley

Creamer³

et al. 1999

Protein Science

131

View full text Add to dashboard Cite

The structure of the trigonal crystal form of bovine b-lactoglobulin variant B at pH 7.1 has been determined by X-ray diffraction methods at a resolution of 2.22 Å and refined to values for R and R free of 0.239 and 0.286, respectively. By comparison with the structure of the trigonal crystal form of bovine b-lactoglobulin variant A at pH 7.1, which was determined previously @Qin BY et al., 1998, Biochemistry 37:14014-14023#, the structural consequences of the sequence differences D64G and V118A of variants A and B, respectively, have been investigated. Only minor differences in the core calyx structure occur. In the vicinity of the mutation site D64G on loop CD~residues 61-67!, there are small changes in main-chain conformation, whereas the substitution V118A on b-strand H is unaccompanied by changes in the surrounding structure, thereby creating a void volume and weakened hydrophobic interactions with a consequent loss of thermal stability relative to variant A. A conformational difference is found for the loop EF, implicated in the pH-dependent conformational change known as the Tanford transition, but it is not clear whether this reflects differences intrinsic to the variants in solution or differences in crystallization.Keywords: bovine b-lactoglobulin; crystal structure; genetic variants; hydrophobic stabilization Bovine b-lactoglobulin~BLG!, the major whey protein of cow's milk at a concentration of 0.3 g0100 mL~Bell & McKenzie, 1964!, was first isolated by Palmer~1934!. Mature bovine b-lactoglobulin has 162 residues, and is a member of the lipocalin protein superfamily~Flower, 1994, 1996!. Members of this family have a distinctive eight-stranded b-barrel structure, the central cavity of which binds a variety of hydrophobic molecules~Banaszak et al., 1994!. In the case of BLG, the primary site for fatty-acid binding has recently been established crystallographically to be inside this cavity~Qin et al., 1998b; Wu et al., 1999!. The structure of BLG is now reliably known following two independent redeterminations of the structure in the triclinic~lattice X!~Brownlow et al., 1997! and orthorhombic~lattice Y! forms~Bewley et al., 1997!. The latter structure has led to our redetermination of the structure in the trigonal~lattice Z! form~Qin et al., 1998a!. In lattice Z, in contrast to lattices X and Y, the entire molecule is well defined from electron density maps.Three variants of BLG, labeled as A, B, and C, commonly occur in cow's milk. Variants A and B~BLGA and BLGB! differ at two sites: Asp64 in A is changed to Gly in B, and Val118 in A is changed to Ala in B. Variants B and C differ at one site: Gln59 in B is changed to His in C. Thus, the isoelectric points for variants A, B, and C differ slightly: pI ϭ 5.26, 5.34, and 5.33, respectively, in 0.1 M KCl at room temperature~McKenzie, 1971!. Of technological significance, bovine BLG variants have different effects on the industrial processing of milk and on the characteristics of milk products~Hill et al., 1996!. Thermal stability is in the order B ...

show abstract

β-Lactoglobulins

Cited by 110 publications

References 161 publications

Bovine ß-Lactoglobulin E, F and G of Bali (Banteng) Cattle, Bos (Bihos) Javanicus

Bovine ß-Lactoglobulin E, F and G of Bali (Banteng) Cattle, Bos (Bihos) Javanicus

A calorimetric study of the thermal denaturation of whey proteins in simulated milk ultrafiltrate

Functional implications of structural differences between variants A and B of bovine β‐lactoglobulin

Contact Info

Product

Resources

About