title: Glycation and phosphorylation of beta-lactoglobulin by dry-heating: effect on protein structure and some properties.
abstract: Beta-lactoglobulin (beta-Lg) was glycated with maltopentaose and subsequently phosphorylated by dry-heating in the presence of pyrophosphate to investigate the structural and functional properties of phosphorylated beta-Lg. The circular dichroism spectra showed that the change of the secondary structure in the beta-Lg molecule by glycation and subsequent phosphorylation was small. The differential scanning calorimetry thermograms of beta-Lg showed that the denaturation temperature of the most stable domain was only slightly affected, whereas the retinol-binding activity of beta-Lg was somewhat reduced by glycation and subsequent phosphorylation. These results indicated that the conformational changes of the beta-Lg molecule by glycation and subsequent phosphorylation were mild. The anti-beta-Lg antibody response was somewhat reduced by glycation, but significant changes were not observed by phosphorylation. Although the stability of beta-Lg against heat-induced insolubility was improved by glycation alone, it was further enhanced by phosphorylation. The calcium phosphate solubilizing ability of beta-Lg was enhanced by phosphorylation following glycation.
authors.affiliation: United Chair of Applied Resource Chemistry, Course of Bioresource Science for Processing, United Graduate School of Agricultural Sciences, Kagoshima University, Kagoshima 890-0065, Japan.
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Enomoto
authors.forename: Can-Peng
authors.initials: CP
authors.lastname: Li
authors.forename: Kentaro
authors.initials: K
authors.lastname: Morizane
authors.forename: Hisham R
authors.initials: HR
authors.lastname: Ibrahim
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Sugimoto
authors.forename: Shinichi
authors.initials: S
authors.lastname: Ohki
authors.forename: Hideo
authors.initials: H
authors.lastname: Ohtomo
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Aoki
mesh_terms: D006031:Glycosylation; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007782:Lactoglobulins / Q000737:chemistry*; D010758:Phosphorus / Q000032:analysis; D010766:Phosphorylation; D011489:Protein Denaturation; D017433:Protein Structure, Secondary; D013329:Structure-Activity Relationship
chemical_list: D007782:Lactoglobulins; D010758:Phosphorus