Two-dimensional 1H-NMR spectroscopy has been used to study the acid-denatured molten globule (A-state) of alpha-lactalbumin. The NMR spectra show that chemical shift dispersion is limited but significantly greater than that expected for a random coil conformation. The small chemical shift dispersion of side-chain resonances in the A-state together with line broadening associated with conformational averaging indicates that most of the long-range tertiary structure in the A-state is likely to be nonspecific. Side-chain resonances in the A-state are generally shifted somewhat upfield of random coil values; this and the observation of a large number of interresidue NOEs, however, indicate that some side-chain interactions, at least at the level of hydrophobic clustering, exist in the A-state. Analysis of NOESY spectra shows no evidence for an ordered structure for either of the two major clusters of aromatic residues which in the native structure make up part of the hydrophobic core of the helical domain of the native protein. A new aromatic cluster in the A-state which results from rearrangement of the side chains of Tyr103, Trp104, and His107 from their native state positions was, however, detected by a number of well-defined interresidue NOE effects. Similar NOE patterns are observed in a peptide corresponding to residues 101-110 of alpha-lactalbumin in trifluoroethanol, suggesting that the non-native structure in the 101-110 region of the A-state is not dependent on specific interactions with the rest of the chain. Trapping experiments indicate that amide protons from regions of the sequence which in the native state are helical are among those strongly protected from solvent exchange in the A-state; those from one of the helices (the C helix) were specifically identified. Taken together, these results reinforce a model of the A-state which has stable regions of localized secondary structure but a largely disordered tertiary structure.
This research output has an Altmetric Attention Score of 3. This is our high-level measure of the quality and quantity of online attention that it has received. This Attention Score, as well as the ranking and number of research outputs shown below, was calculated when the research output was last mentioned on 25 January 2011.
All research outputs
#8,135,326
of 24,397,600 outputs
Outputs from Biochemistry
#7,266
of 22,293 outputs
Outputs of similar age
#41,614
of 124,596 outputs
Outputs of similar age from Biochemistry
#2,708
of 8,388 outputs
Altmetric has tracked 24,397,600 research outputs across all sources so far. This one is in the 44th percentile – i.e., 44% of other outputs scored the same or lower than it.
So far Altmetric has tracked 22,293 research outputs from this source. They receive a mean Attention Score of 4.3. This one is in the 17th percentile – i.e., 17% of its peers scored the same or lower than it.
Older research outputs will score higher simply because they've had more time to accumulate mentions. To account for age we can compare this Altmetric Attention Score to the 124,596 tracked outputs that were published within six weeks on either side of this one in any source. This one is in the 5th percentile – i.e., 5% of its contemporaries scored the same or lower than it.
We're also able to compare this research output to 8,388 others from the same source and published within six weeks on either side of this one. This one is in the 1st percentile – i.e., 1% of its contemporaries scored the same or lower than it.
