Improvement of Functional Properties of Bovine Serum Albumin through Phosphorylation by Dry‐Heating in the Presence of Pyrophosphate

Abstract

Bovine serum albumin (BSA) was phosphorylated by 2 methods. One is dry-heating in the presence of pyrophosphate, and the other is conjugation with maltopentaose through the Maillard reaction and subsequent dry-heating in the presence of pyrophosphate. The phosphorus content of BSA was increased to approximately 0.45% by dry-heating at pH 4.0 and 85 degrees C for 5 d in the presence of pyrophosphate, and approximately 0.91% by glycation and subsequent phosphorylation. The circular dichroism spectra showed that the change of secondary structure in the BSA molecule by phosphorylation was mild. However, tryptophan fluorescence intensity of BSA decreased by phosphorylation. The differential scanning calorimetry thermograms of BSA showed a disappearing of the 1st peak and a lowering of the 2nd peak denaturation temperature by phosphorylation. These results indicated molten (partially unfolded) conformations of BSA formed by both phosphorylation methods. The functional properties of BSA such as heat stability and calcium phosphate solubilizing ability were improved by phosphorylation alone and further by phosphorylation after glycation. Transparent gels of BSA with relatively high water-holding capacity were obtained by phosphorylation alone, and the immunogenicity of BSA was reduced significantly by glycation and phosphorylation, respectively.

Recent advances in phosphorylation of food proteins: A review

“…Due to the more digestible property of PP-EWP than the native one by proteases, the reduced antigenicity of PP-EWP may be expected after ingestion. Enomoto et al (2007Enomoto et al ( , 2008 and Enomoto, Hayashi, et al (2009) reported that the antigenicity of b-Lg and a-La was somewhat reduced by phosphorylation, and that of BSA was reduced significantly by phosphorylation. The reason for this difference is not clear.…”

Phosphorylation of ovalbumin by dry-heating in the presence of pyrophosphate: Effect of carbohydrate chain on the phosphorylation level and heat stability

“…However, whey protein isolate showed a lower phosphorylation level than egg white protein by dry-heating under the same conditions, presumably due to the absence of a carbohydrate chain (Li et al, 2003). So, we attempted to phosphorylate whey protein isolate by glycation with maltopentaose through the Maillard reaction and subsequent dry-heating in the presence of pyrophosphate, with the results that whey proteins were effectively phosphorylated and some functional properties were improved by phosphorylation after glycation (Enomoto et al, 2007(Enomoto et al, , 2008(Enomoto et al, , 2009aLi, Enomoto, Ohki, Ohtomo, & Aoki, 2005a). Furthermore, these two methods of phosphorylation by dry-heating in the presence of pyrophosphate are simple and easily put to practical use.…”

A Comparison of Analytical Methods for Quantifying Denatured Whey Proteins and Their Correlation to Solubility

“…Many researchers have used this method for intrinsic fluorescence with excitation at 280 nm and scanning emission from 300-450 nm (Anand et al, 1998;Enomoto et al, 2008;Marangoni et al, 2000). Peak emission for whey protein is usually at 340nm (Anand et al, 1998).…”

“…However, this is likely due to a lower total protein content in the whey obtained by centrifugal isolation than due a higher degree of isolation. In several studies when native PAGE has been used characterize whey protein denaturation, it is generally a part of a larger scope of gel electrophoresis methods including SDS-PAGE under reducing and/or non-reducing conditions and 2-dimentional PAGE, which allows for subjective comparisons between native and total protein content (Hong and Creamer, 2002;Considine et al, 2007;Chen et al, 2005;Enomoto et al, 2008;Havea et al, 2001;Anand et al, 1998). As previously discussed, the inherent differences from gel to gel and denaturing effects of other PAGE methods make it unrealistic to make such comparisons quantitatively.…”

“…This can clearly be seen in the gels that as the protein band densities decrease in intensity, the density of the aggregate in the sample well increases in intensity and will be discussed further in section 4.2.5.1. Furthermore, when native PAGE has been used to characterize whey protein denaturation, it is generally a part of a larger scope of gel electrophoresis methods including SDS-PAGE under reducing and/or nonreducing conditions and 2-dimentionol PAGE (Hong and Creamer, 2002;Considine et al, 2007;Chen et al, 2005;Enomoto et al, 2008;Havea et al, 2001;Anand et al, 1998). of pH values.…”