Physical and structural studies on the cryocooling of insulin crystals

Ardeschir Vahedi-Faridi, Jeffrey Lovelace, Henry D. Bellamy, Edward H. Snell, Gloria E Borgstahl

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

Reflection profiles were analyzed from microgravity-grown (μg) and earth-grown insulin crystals to measure mosaicity (η) and to reveal mosaic domain structure and composition. The effects of cryocooling on single-domain and multi-domain crystals were compared. The effects of cryocooling on insulin structure were also re-examined. Microgravity crystals were of larger volume, were more homogeneous and were of higher quality than earth crystals. Several μg crystals contained a single mosaic domain which encompassed all or nearly all of the crystal with an ηavg of 0.005°. The earth crystals varied in quality and all contained multiple domains with an η avg of 0.031°. Cryocooling caused a 43-fold increase in η for μg crystals (ηavg = 0.217°) and an eightfold increase for earth crystals (ηavg = 0.246°). These results indicate that very well ordered crystals are not completely protected from the stresses associated with cryocooling, especially when structural perturbations occur. However, there were differences in the reflection profiles. For multi-mosaic domain crystals, each domain individually broadened and separated from the other domains upon cryocooling. Cryocooling did not cause an increase in the number of domains. A crystal composed of a single domain retained this domain structure and the reflection profiles simply broadened. Therefore, an improved signal-to-noise ratio for each reflection was measured from cryocooled single-domain crystals relative to cryocooled multi-domain crystals. The improved signal from μg crystals, along with the increase in crystal size, facilitated the measurement of the weaker high-resolution reflections. The observed broadening of reflection profiles indicates increased variation in unit-cell parameters, which may be linked to cryocooling-associated structural changes and disorder.

Original languageEnglish (US)
Pages (from-to)2169-2182
Number of pages14
JournalActa Crystallographica - Section D Biological Crystallography
Volume59
Issue number12
DOIs
StatePublished - Dec 1 2003

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Weightlessness
insulin
Insulin
Crystals
Signal-To-Noise Ratio
crystals
Earth (planet)
Microgravity
profiles
microgravity

ASJC Scopus subject areas

  • Structural Biology

Cite this

Physical and structural studies on the cryocooling of insulin crystals. / Vahedi-Faridi, Ardeschir; Lovelace, Jeffrey; Bellamy, Henry D.; Snell, Edward H.; Borgstahl, Gloria E.

In: Acta Crystallographica - Section D Biological Crystallography, Vol. 59, No. 12, 01.12.2003, p. 2169-2182.

Research output: Contribution to journalArticle

Vahedi-Faridi, Ardeschir ; Lovelace, Jeffrey ; Bellamy, Henry D. ; Snell, Edward H. ; Borgstahl, Gloria E. / Physical and structural studies on the cryocooling of insulin crystals. In: Acta Crystallographica - Section D Biological Crystallography. 2003 ; Vol. 59, No. 12. pp. 2169-2182.
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