Physicochemical and structural properties of oat globulin polymers formed by a microbial transglutaminase.
Oat globulin was polymerized by a microbial transglutaminase (TG), and some physicochemical and functional properties of polymers were studied. Reversed-phase HPLC revealed that the number of epsilon-(gamma-glutamyl) lysine isopeptide bonds formed after 4 h of enzyme incubation was 2.21 micromol/g of protein. SDS-PAGE showed that the oat globulin acidic polypeptides (AP) were more susceptible to polymerization than the basic polypeptides (BP), and the reactivities of both AP and BP were enhanced by the addition of other substrate proteins. Differential scanning calorimetry showed that both the denaturation temperature and denaturation enthalpy were decreased after TG treatment. Fourier transform infrared spectroscopy revealed marked increases in the intensity of two intermolecular beta-sheet bands associated with aggregate formation but little conformational changes in the polymerized protein. TG incubation led to progressive changes in flow properties of oat globulin dispersions, indicating enhanced pseudoplasticity and increased viscosity and yield stress.
Siu
Nai-Chi
NC
Food Science Laboratory, Department of Botany, The University of Hong Kong, Pokfulam Road, Hong Kong, ROC.
Ma
Ching-Yung
CY
Mine
Yoshinori
Y
D018554:Avena / Q000737:chemistry*; D002152:Calorimetry, Differential Scanning; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D002851:Chromatography, High Pressure Liquid; D004591:Electrophoresis, Polyacrylamide Gel; D010940:Plant Proteins / Q000737:chemistry* / Q000378:metabolism; D011108:Polymers / Q000737:chemistry* / Q000378:metabolism; D011489:Protein Denaturation; D012212:Rheology; D012639:Seeds / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D013816:Thermodynamics; D011503:Transglutaminases / Q000378:metabolism*
D010940:Plant Proteins; D011108:Polymers; D011503:Transglutaminases