thermal denaturation of a-lactalbumin in the absence and presence of various concentrations of sucrose,sorbitol, glucose and galactose as sugar osmolytes were measured by monitoring changes in the absorptions thatcarried out in a lambd 35 uv-vis double beam spectrophotometer at ph 6.0. these measurements gave valuesof t., (midpoint of denaturation), ah., (enthalpy change at t.), and acp (consta...

Studies in the accompanying paper (Chen, W. W., and Lennarz, W. J. (1978) J. Biol. Chem. 253, 5774-5779) showed that hen oviduct membranes catalyze synthesis of a Glc-containing oligosaccharide-lipid and that the oligosaccharide moiety of this compound is transferred en bloc to an endogenous protein as well as to an exogenous, soluble protein. In this study we have established that the endogene...

Understanding the mechanisms of protein folding requires knowledge of both the energy landscape and the structural dynamics of a protein. We report a neutron-scattering study of the nanosecond and picosecond dynamics of native and the denatured alpha-lactalbumin. The quasielastic scattering intensity shows that there are alpha-helical structure and tertiary-like side-chain interactions fluctuat...

We present entropy estimates based on molecular dynamics simulations of models of the molten globule state of the protein alpha-lactalbumin at low pH. The entropy calculations use the covariance matrix of atom-positional fluctuations and yield the complete configurational entropy. The configurational entropy of the entire protein and of each of its side chains is calculated. Exposed side chains...

Foldons, which are kinetically competent, quasi-independently folding units of a protein, may be defined using energy landscape analysis. Foldons can be identified by maxima in a scan of the ratio of a contiguous segment's energetic stability gap to the energy variance of that segment's molten globule states, reflecting the requirement of minimal frustration. The predicted foldons are compared ...

1. Two enzymes that catalyse the transfer of galactose from UDP-galactose to GM2 ganglioside were partially purified from rat liver Golgi membranes. 2. These preparations, designated enzyme I (basic) and enzyme II (acidic), utilized as acceptors GM2 ganglioside and asialo GN12 ganglioside as well as ovalbumin, desialodegalactofetuin, desialodegalacto-orosomucoid, desialo bovine submaxillary muc...

The ability of proteins to fold to well defined compact structures is one of the most remarkable examples of the effect of natural selection on biological molecules. To understand their properties, including the stability, the mechanism of folding, and the possibilities of misfolding and association, it is necessary to know the protein free energy landscape. We use NMR data as restraints in a M...

Of the 4 tyrosyl residues of bovine ar-lactalbumin, 2 were found to be quite reactive with N-acetylimidazole; the third group is less so, and the fourth is only weakly reactive. Acylation of the two most reactive groups results in a reversible increase in the quantum yield of a tryptophan residue or residues which emit maximally at 350 rnp. At relatively high concentrations of reagent, in addit...

alpha-Lactalbumin (alpha-LA) is a two-domain, calcium-binding protein that forms one of the best studied molten globules. We present here amide hydrogen exchange studies of the molten globule formed by human alpha-LA at pH 2 and compare these results with a similar study of the native state at pH 6.3. The most persistent structure in the molten globule is localized in the helical domain, consis...