A partially folded state of guinea pig alpha-lactalbumin (the A-state or molten globule state), formed by denaturation at low pH, has been studied using hydrogen exchange methods. The overall distribution of exchange kinetics, measured by 1-D NMR, suggests that fewer than 20 amides in the structure are involved in highly persistent residual structure, although CD results suggest that many other parts of the chain are folded, for a significant proportion of the time, into less stable structural elements. The pH-jump experiments show that some amides that are strongly protected from exchange in the native state become freely accessible in the A-state but that conversely a majority, at least, of those that are slow to exchange in the A-state retain that protection in the native state. This suggests that the persistent structure in the A-state is native-like although the possibility that nonnative like structural elements persist cannot be eliminated. Resonance assignments for key residues in the NMR spectrum of the native state have enabled us to use the pH-jump method also to identify the majority of the most protected amides in the A-state: they are located in two hydrophobic segments, corresponding to the B- and C-helices of the native structure. This strongly suggests that the most persistent structure of the A-state includes these regions. A variety of lines of evidence, including fluorescence quenching data and, most remarkably, very effective protection from exchange of an indole NH in a tryptophan side chain, suggest that some form of hydrophobic core in the helical domain of the native structure persists in the A-state, although without the stereochemical rigidity of the native tertiary structure. The other domain of the native structure, including the beta-sheet, appears not to contain structural elements which persist to the same extent in the A-state, emphasizing that the molten globule is highly heterogeneous, in terms of the stability and specificity of both backbone and side chain interactions.
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.
