Human milk bile-salt-stimulated lipase is extremely reactive with the monoclonal antibody 1CF11 which recognizes a human-specific carbohydrate antigen.

1CF11 (Kanamaru, Y. et al.; Biochem. Biophys. Res. Commun., 249, 618-623, 1998) is a monoclonal antibody obtained after being raised in a mouse by injection of human milk MUC1 mucin as the antigen. Its reactivity was found to be unique in that it only reacts with a carbohydrate epitope shared by glycoproteins in human secretions, while its chemical nature is still unknown. Since a glycoprotein of Mr 135,000 (135K) in human milk was found to react extremely strongly with this antibody, we intended in this study to isolate the glycoprotein by a combination of various chromatographic techniques and identify it. It is a human milk bile-salt-stimulated lipase. By comparison of its immunoreactivity and glycan structures so far reported with those of lactoferrin from human milk, it is suggested that the epitope recognized by mAb ICF11 could be a human-specific novel glycan.

Inhibition against heat coagulation of ovotransferrin by ovalbumin dry-heated at 120 degrees C.

Ovalbumin (OVA) was aggregated stepwise by dry heating at 120 degrees C with a gradual increase in its heating times (10 min-6 h). The inhibiting effects of DHOVAs (OVAs dry-heated for various times up to 6 h) on the heat coagulation of ovotransferrin (OT) were studied. DHOVAs and OT were solubilized at 5% (w/w) concentration with 10 mM sodium phosphate buffer, pH 7.4. Their solutions were mixed at the volume ratio of 1:1 and reheated at 60 degrees C for 3. 5 min. Some remarkable differences according to dry-heating time were observed: coagulum formations were greatly inhibited in the solutions mixed with DHOVAs treated for more than around 2.0 h, with decreasing turbidity as dry-heating time increased. In addition, the effects of reheating time and temperature, as well as those of pH and ionic strength, were also examined on coagulum formation and turbidity development in connection with dry-heating time. Thus, the inhibiting effects of dry-heated egg white on the heat coagulation of fresh egg white previously described were confirmed on the molecular level of OVA and OT.

Interactions among protein molecules in freeze-gel of soymilk and protein structures in heated soymilk during cooling.

To estimate the interactions forming in soymilk freeze-gel, lyophilized gel was extracted successively with various solvents. A mixture of urea, sodium dodecyl sulfate (SDS), and 2-mercaptoethanol (2-ME) dissolved the proteins effectively. The thiol-disulfide exchange reactions and hydrophobic interactions were shown to have a complex relation with a three-dimensional network. The addition of SDS or 2-ME resulted in an incomplete gel or no precipitation of soymilk. In our previous paper (Shimoyamada et al. Food Sci. Technol. Res. 1999, 5, 284-288), the significance of precooling to form small, homogeneously distributed ice crystals in soymilk was reported. In this study, precooling was shown to maintain the partially denatured structures of soybean proteins in soymilk that had unfolded due to heat treatment. These phenomena were considered to be other important functions of precooling in freeze-gelation.

Effects of soybean saponin on protease hydrolyses of beta-lactoglobulin and alpha-lactalbumin.

Effects of Soybean Saponin on Protease Hydrolyses of beta-Lactoglobulin and alpha-Lactalbumin The effects of soybean saponin on tryptic and chymotryptic hydrolyses of whey proteins were evaluated. beta-lactoglobulin and alpha-lactalbumin became more sensitive to both trypsin and chymotrypsin by interacting with saponin in contrast to serum albumin. Soybean saponin was shown to have different effects on various proteins according to their nature.

Inhibiting effects of egg white dry-heated at 120 degrees C on heat aggregation and coagulation of egg white and characteristics of dry-heated egg white.

Dialyzed and freeze-dried egg white (FDEW) was dry-heated at 120 degrees C for up to 6 h. The inhibiting effects of the dry-heated egg white (DHEW) on the heat aggregation and coagulation of egg white (as 10% FDEW solution) and characteristics of the DHEW were examined. From the changes in turbidities and soluble protein contents of supernatant in various mixtures of 10% FDEW and DHEW solutions induced by heating (60 degrees C, 5 min), it was found that the inhibiting capacity increased with increases in the dry-heating time (DHT). The FDEW proteins were denatured with a mild conformational change (not secondary but tertiary structure) with the increase in DHT and aggregated partially. However, the more transparent solutions of DHEW containing soluble aggregates according to DHT were also obtained after heating. The transparency according to DHT came to be scarcely affected by the NaCl concentration and the dilution with diluents containing SDS, urea, and 2-mercaptoethanol. These findings suggest that the heat aggregations and coagulations of ovotransferrin and lysozyme in the FDEW were inhibited by their bindings with the soluble aggregates in DHEW.

Binding of egg white proteins to viruses.

The binding of some egg white proteins to bovine rotavirus, hen new castle disease virus (NDV), and human influenza virus (IV) was investigated by using the hemagglutination inhibition (HI) test and supplemented by an enzyme-linked immunosorbent assay (ELISA). In comparison with other egg white proteins, ovomucin showed the highest affinity for the three viruses, while ovomucoid showed only slight affinity for NDV in the HI test and ELISA.

Differences in hemagglutination inhibition activity against bovine rotavirus and hen Newcastle disease virus based on the subunits in hen egg white ovomucin.

The hemagglutination inhibition (HI) activity of ovomucin (OM) subunits, and the effects of alkylation before and after reduction and protease treatments on the HI activity of OM to bovine rotavirus (RV) and hen newcastle disease virus (NDV) were investigated. The appearance of the HI activity of Om against RV was accomplished by a macromolecule composed of alpha- and beta-subunits, while that against NDV required the beta-subunit moiety only.

Hypocholesterolemic effects of saponins.

On the basis of the literature the results of experimental investigations on hypocholesterolemic action of saponins are demonstrated. Also the theories explaining the mechanism of this action are discussed.