title: Sequence and properties of HMW subunit 1Bx20 from pasta wheat (Triticum durum) which is associated with poor end use properties.
abstract: The gene encoding high-molecular-weight (HMW) subunit 1Bx20 was isolated from durum wheat cv. Lira. It encodes a mature protein of 774 amino acid residues with an M(r) of 83,913. Comparison with the sequence of subunit 1Bx7 showed over 96% identity, the main difference being the substitution of two cysteine residues in the N-terminal domain of subunit 1Bx7 with tyrosine residues in 1Bx20. Comparison of the structures and stabilities of the two subunits purified from wheat using Fourier-transform infra-red and circular dichroism spectroscopy showed no significant differences. However, incorporation of subunit 1Bx7 into a base flour gave increased dough strength and stability measured by Mixograph analysis, while incorporation of subunit 1Bx20 resulted in small positive or negative effects on the parameters measured. It is concluded that the different effects of the two subunits could relate to the differences in their cysteine contents, thereby affecting the cross-linking and hence properties of the glutenin polymers.
authors.affiliation: Long Ashton Research Station, Department of Agricultural Sciences, University of Bristol, Long Ashton, UK. peter.shewry@bbsrc.ac.uk
authors.forename: P R
authors.initials: PR
authors.lastname: Shewry
authors.forename: S M
authors.initials: SM
authors.lastname: Gilbert
authors.forename: A W J
authors.initials: AW
authors.lastname: Savage
authors.forename: A S
authors.initials: AS
authors.lastname: Tatham
authors.forename: Y-F
authors.initials: YF
authors.lastname: Wan
authors.forename: P S
authors.initials: PS
authors.lastname: Belton
authors.forename: N
authors.initials: N
authors.lastname: Wellner
authors.forename: R
authors.initials: R
authors.lastname: D'Ovidio
authors.forename: F
authors.initials: F
authors.lastname: Békés
authors.forename: N G
authors.initials: NG
authors.lastname: Halford
mesh_terms: D000595:Amino Acid Sequence; D002942:Circular Dichroism; D003433:Crosses, Genetic; D003545:Cysteine / Q000737:chemistry; D004591:Electrophoresis, Polyacrylamide Gel; D005983:Glutens / Q000031:analogs & derivatives* / Q000737:chemistry; D008969:Molecular Sequence Data; D008970:Molecular Weight; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D017550:Spectroscopy, Fourier Transform Infrared; D014908:Triticum / Q000235:genetics*; D014443:Tyrosine / Q000378:metabolism
chemical_list: D014443:Tyrosine; D005983:Glutens; C037302:glutenin; D003545:Cysteine