+ Site Statistics
+ Search Articles
+ PDF Full Text Service
How our service works
Request PDF Full Text
+ Follow Us
Follow on Facebook
Follow on Twitter
Follow on LinkedIn
+ Subscribe to Site Feeds
Most Shared
PDF Full Text
+ Translate
+ Recently Requested

Aggregation of bovine insulin probed by DSC/PPC calorimetry and FTIR spectroscopy

Aggregation of bovine insulin probed by DSC/PPC calorimetry and FTIR spectroscopy

Biochemistry 42(38): 11347-11355

Pressure perturbation calorimetry (PPC), differential scanning calorimetry (DSC), and time-resolved Fourier transform infrared spectroscopy (FTIR) have been employed to investigate aggregation of bovine insulin at pH 1.9. The aggregation process exhibits two distinguished phases. In the first phase, an intermediate molten globule-like conformational state is transiently formed, reflected by loose tertiary contacts and a robust H/D-exchange. This is followed by unfolding of the native secondary structure. The unfolding of insulin is fast, endothermic, partly reversible, and accompanied by a volume expansion of approximately 0.2%. The second phase consists of actual aggregation: an exothermic irreversible process revealing typical features of nucleation-controlled kinetics. The volumetric changes associated with the second phase are small. The concentration-dependence of DSC scans does not support a monomer intermediate model. While insulin aggregation under ambient pressure is fast and quantitative, pressure as low as 300 bar is sufficient to prevent the aggregation completely, as high-pressure FTIR spectroscopy revealed. This is explained in terms of the high pressure having an adverse effect on the thermal unfolding of insulin, and therefore preventing occurrence of the aggregation-prone intermediate. A comparison of the aggregation in H(2)O and D(2)O shows that the isotopic substitution has diverse effects on both the phases of aggregation. In heavy water, a more pronounced volume expansion accompanies the unfolding stage, while only the second phase shifts to higher temperature.

Please choose payment method:

(PDF emailed within 0-6 h: $19.90)

Accession: 009762824

Download citation: RISBibTeXText

PMID: 14503885

DOI: 10.1021/bi034879h

Related references

Structural changes of cytochrome c(552) from Thermus thermophilus adsorbed on anionic and hydrophobic surfaces probed by FTIR and 2D-FTIR spectroscopy. Chembiochem 2(3): 180-189, 2001

Oligomerization and aggregation of bovine pancreatic ribonuclease A: characteristic events observed by FTIR spectroscopy. Biophysical Journal 90(7): 2525-2533, 2006

Aggregation kinetics of bovine serum albumin studied by FTIR spectroscopy and light scattering. Biophysical Chemistry 107(2): 175-187, 2004

Rhodopsin chromophore probed by polarized ftir difference spectroscopy. Biophysical Journal 51(2 Part 2): 268A, 1987

Evidence of pressure enhanced CO2 storage in ZIF-8 probed by FTIR spectroscopy. Journal of the American Chemical Society 135(25): 9287-9290, 2013

Secondary structure and conformational changes associated with desensitization of the nAChR probed using FTIR spectroscopy. Biophysical Journal 66(2 Part 2): A212, 1994

Study of starch retrogradation by micro-calorimetry, X-ray diffractometry and FTIR spectroscopy. Cereal Foods World 42(8): 641-642, 1997

Blue-light-induced changes in Arabidopsis cryptochrome 1 probed by FTIR difference spectroscopy. Biochemistry 45(8): 2472-2479, 2006

Phenol chemisorption onto phthalocyanine thin layers probed by ATR-FTIR difference spectroscopy. Physical Chemistry Chemical Physics 11(13): 2161-2165, 2009

Interactions of albumin with bovine pulmonary surfactant dispersions probed using DSC and FTIR. Biophysical Journal 86(1): 375a, 2004

Dynamics and flexibility of human aromatase probed by FTIR and time resolved fluorescence spectroscopy. Plos one 8(12): E82118, 2013

Conformations of phenylalanine in the tripeptides AFA and GFG probed by combining MD simulations with NMR, FTIR, polarized Raman, and VCD spectroscopy. Journal of Physical Chemistry. B 114(11): 3965-3978, 2010

Membrane structure of normal and dystrophic RCS rat retinal rod outer segments as probed by FTIR spectroscopy. Investigative Ophthalmology & Visual Science 36(4): S914, 1995

Hydrogen bonding of redox-active tyrosine Z of photosystem II probed by FTIR difference spectroscopy. Biochemistry 37(30): 10547-10554, 1998