Three-chain merokeratin from wool may be a fragment of the microfibril component macromolecule

Lotay, S. S.; Speakman, P. T.

doi:10.1038/265274a0

Cited by 11 publications

(5 citation statements)

References 12 publications

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“…neighboring regions of nonhelix in such a-type proteins as myosin (Lowey et ah, 1969), the wool "low-sulfur" proteins (Crewther et ah, 1971; Lotay & Speakman, 1977), and bovine epidermal keratin filaments (Steinert, 1978). In each of these cases, a-helix-enriched fractions were obtained which provided information on the ultrastructure of the fibrous protein.…”

Section: Resultsmentioning

confidence: 99%

“…Interestingly, three-chained coiled-coil a-helical particles of similar dimensions and properties have been isolated by limited proteolysis of several a-keratin proteins; wool "lowsulfur" proteins (Crewther & Dowling, 1971; Lotay & Speakman, 1977), epidermal prekeratin (Skerrow et al, 1973), and bovine epidermal keratin filaments (Steinert, 1978).…”

Section: Resultsmentioning

confidence: 99%

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Structural features of the α-type filaments of the inner root sheath cells of the guinea pig hair follicle

Steinert¹

1978

Biochemistry

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Structural features of the α-type filaments of the inner root sheath cells of the guinea pig hair follicle

Steinert¹

1978

Biochemistry

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“…An analogous three-chain structure has also been proposed for the hard a-keratin from similar studies of the highly a-helical fragments isolated from the microfibrillar proteins of wool (Crewther et al, 1968;Crewther & Dowling, 1971). However, more-recent studies on the proteolytic fragments from wool (Campbell et al, 1976;Lotay & Speakman, 1977;Ahmadi & Speakman, 1978;Ahmadi et al, 1980) have cast doubt on a three-chain structure, and instead have favoured a four-chain structure. From a study of models of the helical portions of wool a-keratin of known sequence, McLachlan (1978) has concluded that the two-strand rope is more likely than a three-strand rope for wool.…”

mentioning

confidence: 99%

Structural studies on the microfibrillar proteins of wool. Interaction between α-helical segments and reassembly of a four-chain structure

Gruen¹,

Woods²

1983

Biochemical Journal

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The alpha-helix-rich particle of Mr 50 200, derived by limited alpha-chymotryptic digestion of the solubilized microfibrillar proteins from wool alpha-keratin, consists mainly of polypeptide-chain segments of Mr 12 500 (fraction ChC) and 25 000 (fraction ChB). The 12 500-Mr segments are of two types (I and II), which are derived from different polypeptide chains of the microfibrillar complex. Each of these type-I and type-II segments partially self-associates in benign solvents to form either dimers or tetramers. When mixed, the two segments show changes in physical properties (alpha-helix content, difference spectra and molecular weight) indicative of complex-formation. The maximum changes occur when the two segments are mixed in an equimolar ratio. Complexes isolated after rapid dialysis of mixtures from 8 M-urea solution were examined by various methods. A tetrameric structure is the main product formed in all cases, and the maximum amount of tetramer is obtained from equimolar mixtures of the type-I and type-II polypeptides. When urea is removed by dialysis from the unfractionated 12 500-Mr segments (fraction ChC) or from the alpha-helix-rich particle itself, a similar complex of Mr 50 000 is formed. The physical properties of these reconstituted entities (alpha-helix content, molecular weight, thermal stability and exposure of tyrosine residues) are similar to those of the original alpha-helix-rich particle. Cross-linking experiments with dimethyl suberimidate are in agreement with a four-chain complex for the reassembled structures. A pair of double-stranded alpha-helices is proposed for the particle, and is considered to be an integral part of the microfibrillar complex in wool alpha-keratin.

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“…Speakman and collaborators (Campbell et al 1976;Lotay and Speakman 1977;Ahmadi and Speakman 1978;Ahmadi et al 1980) have prepared a highly IX-helical, rod-shaped particle, which they termed merokeratin AI, by limited tryptic digestion of reduced wool. From molecular weight studies in the ultracentrifuge and sodium dodecyl sulfate polyacrylamide gel electrophoresis they were unable to say whether there were three or four polypeptide chains in the particle.…”

Section: Introductionmentioning

confidence: 99%

Structural Studies on the Microfibrillar Proteins of Wool: Characterization of the a-Helix-Rich Particle Produced by Chymotryptic Digestion

Woods¹,

Gruen²

1981

Aust. Jnl. Of Bio. Sci.

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The oc-helix-rich particle produced bychymotryptic digestion of the reduced and alkylated microfibrillar proteins of wool was characterized by physicochemical methods. The preparations were homogeneous with respect to size and the particle molecular weight was found to be 50200 ± 2 000.Hydrodynamic methods indicated a length of about 20 nm for the particle. The properties of the particle, derived from two methods of isolation of the microfibrillar proteins, were identical and were also independent of the type of wool used. From a consideration of the molecular weight in denaturing solvents and from cross-linking experiments with dimethyl suberimidate a four-chain structure, consisting of a pair of double-stranded oc-helices, is proposed for the particle.

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Three-chain merokeratin from wool may be a fragment of the microfibril component macromolecule

Cited by 11 publications

References 12 publications

Structural features of the α-type filaments of the inner root sheath cells of the guinea pig hair follicle

Structural features of the α-type filaments of the inner root sheath cells of the guinea pig hair follicle

Structural studies on the microfibrillar proteins of wool. Interaction between α-helical segments and reassembly of a four-chain structure

Structural Studies on the Microfibrillar Proteins of Wool: Characterization of the a-Helix-Rich Particle Produced by Chymotryptic Digestion

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