X-ray studies on human insulins prepared by semisynthetic and biosynthetic methods have recently been undertaken. Human insulin differs from porcine insulin only at the COOH terminus of the B-chain. The present study reports the crystal structure of 4-zinc human insulin, which is used clinically as a slow-acting preparation. The structure has been refined, using 1.85-A resolution data, to a residual of 0.173. The unit cell is rhombohedral, space group R3, with hexagonal cell constants a = 80.953 and c = 37.636 A, and it is nearly isomorphous with that of 4-zinc porcine insulin. As a result of a conformational change of the first eight residues of the B-chain of molecule 1 from an extended conformation observed in the 2-zinc structure to an alpha-helical one, the coordination around one of the zinc ions on the 3-fold axis has changed, an additional zinc ion in a general position is bound by the hexamer, and additional hydrogen-bonded interactions help stabilize dimer and hexamer formation. Unlike the surface of the 2-zinc insulin hexamer, which possesses a shallow depression containing a zinc ion and its coordinating water molecules, the 4-zinc human insulin hexamer contains a zinc and chloride ion at the bottom of an 8-A tunnel produced by three parallel alpha-helices. These alpha-helices shield the zinc ion from the environment, decreasing the rate of dissociation of the hexamer, and provide an explanation for the slow-acting aspect of the 4-zinc crystalline form.
Pharmacology, Toxicology and Pharmaceutical Science
5
6%
Medicine and Dentistry
5
6%
Other
11
14%
Unknown
16
21%
Attention Score in Context
Attention Score in Context
This research output has an Altmetric Attention Score of 9. 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 13 November 2018.
All research outputs
#5,176,099
of 34,518,147 outputs
Outputs from Proceedings of the National Academy of Sciences of the United States of America
#48,742
of 119,104 outputs
Outputs of similar age
#1,042
of 14,048 outputs
Outputs of similar age from Proceedings of the National Academy of Sciences of the United States of America
#32
of 205 outputs
Altmetric has tracked 34,518,147 research outputs across all sources so far. Compared to these this one has done well and is in the 83rd percentile: it's in the top 25% of all research outputs ever tracked by Altmetric.
So far Altmetric has tracked 119,104 research outputs from this source. They typically receive a lot more attention than average, with a mean Attention Score of 40.1. This one has gotten more attention than average, scoring higher than 52% of its peers.
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 14,048 tracked outputs that were published within six weeks on either side of this one in any source. This one has done well, scoring higher than 86% of its contemporaries.
We're also able to compare this research output to 205 others from the same source and published within six weeks on either side of this one. This one has gotten more attention than average, scoring higher than 72% of its contemporaries.
