Nitration of tyrosyl residues in human α lactalbumin. Effect on lactose synthase specifier activity

SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Heterogeneity of human milk β(1-4) D galactosyltransferase

β(1-4) Galactosyltransferase from human milk (the A protein of lactose synthase) has been found to be heterogeneous when fractionated by affinity chromatography against insolubilized α lactalbumin, using a linear gradient of decreasing N acetylglucosamine concentration. Three forms were isolated. Molecular weights of the different species, as determined by sodium dodecylsulphate gel electrophoresis, were found to be 38000, 43000 and 50000. The 38000 and 50000 species were studied for their catalytic ability to synthesize either lactose in the presence of α lactalbumin, or N acetyllactosamine in the presence and absence of the 'specifier' protein. Appreciable difference was observed between the two enzyme forms with respect to their catalysis of lactose synthesis with α lactalbumins from various sources. Differences in the rate of production of N acetyllactosamine in the presence of α lactalbumin were also observed. For the lowest molecular weight species it was found that the inhibitory effect of α lactalbumin upon N acetyllactosamine synthesis becomes an activating effect at higher α lactalbumin concentrations, while no such inversion was observed for the other species. The results suggest that the conformation at the site of association of the enzyme with the acceptor saccharide or α lactalbumin has been changed, presumably by a partial enzymic hydrolysis.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Immunological cross reactions of α lactalbumins from different species

SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Comparative physicochemical studies of human α-lactalbumin and human lysozyme

As a result of the recent disclosure of the striking similarities between the covalent structures of bovine α-lactalbumin and of hen egg-white lysozyme, comparative physicochemical properties of α-lactalbumins and lysozymes of various sources seemed worth investigating. Therefore human milk α-lactalbumin and human milk or urinary lysozyme were purified. Their physical properties were examined in order to study the extent of similarity of the three-dimensional structure when considering the two proteins from the same species. Diffusion and sedimentation experiments showed that the hydrodynamic shape and the molecular weight of human α-lactalbumin and lysozyme were strikingly comparable. Concerning the secondary structure, it was observed by optical rotatory dispersion and circular dichroism that human lysozyme displays slightly more helix than human α-lactalbumin. Furthermore, when considering thermal denaturation, the transition temperatures and changes in enthalpy or entropy are all markedly lower for human α-lactalbumin than for lysozyme. These findings have been discussed in relation to the physicochemical properties of bovine α-lactalbumin and egg-white lysozyme. © 1972.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Properties of galactosyltransferase from human milk fat globules

SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Reoxidation of peptide 1-123 from reduced hen egg-white lysozyme

SCOPUS: ar.jinfo:eu-repo/semantics/publishe