| Project/Area Number |
08458005
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (B)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
家政学
|
|---|
| Research Institution | Nara Women's University |
|---|
Principal Investigator |
YOKOIGAWA Kumio Nara Women's Univ.Faculty of Human Life & Environ., Associate Prof., 生活環境学部, 助教授 (60230637)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
KAWAI Hiroyasu Nara Women's Univ.Faculty of Human Life & Environ., Prof., 生活環境学部, 教授 (80026525)
|
|---|
| Project Period (FY) |
1996 – 1997
|
| Project Status |
Completed (Fiscal Year 1997)
|
| Budget Amount *help |
¥8,200,000 (Direct Cost: ¥8,200,000)
Fiscal Year 1997: ¥2,300,000 (Direct Cost: ¥2,300,000)
Fiscal Year 1996: ¥5,900,000 (Direct Cost: ¥5,900,000)
|
|---|
| Keywords | psychrotroph / alanine racemase / growth suppression / food hygiene |
|---|
| Research Abstract |
We examined the conditions for grwoth inhibition of psychrotrophs in foods on the basis of properties of a psychrotrophic enzyme. A psychrotrophic alanine racemase from a typical psychrotroph, Pseudomonas fluorescens, was purified to homogeneity and characterized. The enzyme was easily inactivated by heat-treating at over 30ﾟC and by incubating with low concentration of organic solvents and denaturants. These treatments also suppressed the growth of the psychrotroph. Analysis of the denaturation process of the enzyme suggest that pyridoxal 5'-phosphate (PLP) plays an important role in maintaining the secondary structure of the thermolabile enzyme. We cloned and expressed the psychrotrophic alanine racemase gene from Bacillus psychrosaccharolyticus into E.coli SOLR.The enzyme was purified to homogeneity from the cell extract of a clone carrying the plasmid pYOK3 (6.3kbp) and characterized. The enzyme from B.psychrosaccharolyticus shows a high catalytic activity even at 0ﾟC,but is easily inactivated by heat-treating at over 35ﾟC and by incubating with low concentration of organic solvents and denaturants. Determination of km value for PLP and stability in the presence of PLP suggests that the enzyme probably looses PLP during the racemization of the substrate at high temperature. Dissociation of PLP from the enzyme protein may be related to the change of the tertiary structure followed by the inactivation. Growth of psychrotrophs was easily suppressed by addition of low concentration of ethanol.
|
