Development of safe food additive having antiviral and antimicrobial effects by polyglycosylation of food protein

2000 Fiscal Year Final Research Report Summary

• Project/Area Number: 11660134
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: 食品科学・栄養科学
• Research Institution: Shimane University
• Principal Investigator: NAKAMURA Soichiro Shimane University, Department of Education Professor, 教育学部, 教授 (00105305)
• Co-Investigator(Kenkyū-buntansha): GOTOH Masayuki Ube College, Department of Environmental Science, Professor, 環境衛生学科, 教授 (90105304)
• Project Period (FY): 1999 – 2000
• Keywords: food protein / polyglycosylation / antimicrobacterial effect / antiviral effect / food safety / food additive

Research Abstract

This study deals with the development of safe food additive having antiviral and antimicrobial effects by chemical and genetic polyglycosylation of lactoferrin and cystatin. Naturally occurring Maillard reaction at 65℃ and 79% RH and a yeast expression system using Pichia pastoris were used as the modifications, respectively. Molecular stability and surface functional property of the food protiens were significantly improved by the both polyglycosylations. Polyglycosylated cystatins showed a strong ability to prevent infection of Salmonella typhimurium to CV-1 cells, compared to the native form. Antiviral function against rotavirus was also improved by the polyglycosylations. A recombinant glycosylated cystatin with a polymannosyl chain was added to roeherring surimi for preventing gel weakening due to autolysis during cooking. Proteolysis of myosin heavy chain in the surimi was effectively suppressed, while cooking at 90℃ for 20 min after preincubation at 40℃ for 30 min. The glycosylation of cystatin improved the stability against heating as well as proteolysis by cathepsin D.This process markedly improved the texture of the cooked surimi gel with gel strength 2.5 times greater than that of unglycosylated control cystatin. In addition, food safety of the polyglycosylated proteins was confirmed by bacterial mutagenesis tests and animal dose experiment using rats. Thus, it is revealed that polyglycosylated proteins gain great potential of the application as food and pharmaceutical aids. This study shows that polyglycosylation of protein is a new approach to enhance the molecular stability and functional properties.