Shigenori Maezawa

Raman studies of bovine serum albumin-ionic detergent complexes and conformational change of albumin molecule induced by detergent binding

Abstract The Raman spectra of bovine serum albumin-detergent complexes were measured. Detergents used here were sodium dodecyl sulfate and tetradecyltrimethylammonium bromide. The secondary structural change of the protein caused by the detergent binding was confirmed by observations of the amide I, III and a skeletal vibrational region. The population of the gauche, gauche and trans conformation about the C-S-S-C group was found to increase with an increase in the concentration of both detergents. When SH-blocked bovine serum albumin was complexed with tetradecyltrimethylammonium bromide, the Raman line was observed at 540 cm −1 which was assigned to the trans, gauche and trans conformation about the C-S-S-C group. The local environment change of tyrosine residues was also observed upon the complexing.

A consideration on afterripening management of kiwifruits based on relation between fruit density and sugar content

A high precision non-destructive measurement technique for early kiwifruit sugar content estimation was proposed. Sugar contents of matured kiwifruits were estimated at harvest when the fruits were still immature. By estimating density of the immature fruit, starch content can be determined that was found closely related to sugar content of the fruit when it is fully matured. The fruit density was calculated from weight and volume information of the fruit. Considering the fact that the range of densities of kiwifruit is very narrow (about 1.02~1.06g/cm3), the measurement of volume requires high accuracy. In this study, the volume of about 2000 kiwifruits at harvest was measured with a Helmholtz acoustic resonance method that offered good correlation with a reference method with R2=0.9254, SEP=0.0019g/cm3. The fruit weight was measured with an electronic scale. The relationship between the fruit density at harvest and sugar content following ethylene treatment was also verified. The proposed system can be used for precision grading of kiwifruit quality based on prediction of sugar contents.