Oligomerization and aggregation of bovine pancreatic ribonuclease A: characteristic events observed by FTIR spectroscopy.
Nonnative protein aggregation, which is a common feature in biotechnology, is also a clinical feature in more than 20 serious degenerative diseases. We studied the specific events of bovine pancreatic ribonuclease A thermal aggregation by a combination of second derivative infrared analysis and two-dimensional infrared correlation spectroscopy. By comparing the events that occur in reversible and irreversible thermal unfolding processes, certain events that were related to protein aggregation were characterized. Particularly, a band that appeared at high temperatures was assigned to the cross beta-structures in oligomers. The effect of pH, NaCl, and ethanol on ribonuclease A oligomerization as well as further aggregation induced by heat were studied and dissimilar effects of these additives were found. Basic pH and NaCl could accelerate the thermal aggregation but did not affect the formation of oligomers, whereas ethanol could increase both the aggregation rate and the population of oligomers. Our results suggested that the aggregation of RNase A might be initiated by hydrophobic interactions, controlled by oligomerization and mediated by electrostatic interactions. Moreover, the strategy of using second derivative and two-dimensional infrared analysis might provide a potential powerful tool to study the events that are directly related to the initiation of protein aggregation.
Yan
Yong-Bin
YB
Department of Biological Sciences and Biotechnology, and State Key Laboratory of Biomembrane and Membrane Biotechnology, Tsinghua University, Beijing 100084, China. ybyan@tsinghua.edu.cn
Zhang
Jun
J
He
Hua-Wei
HW
Zhou
Hai-Meng
HM
D000818:Animals; D001224:Aspartic Acid / Q000737:chemistry; D002417:Cattle; D002942:Circular Dichroism; D000431:Ethanol / Q000737:chemistry / Q000494:pharmacology; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D010179:Pancreas / Q000201:enzymology*; D011485:Protein Binding; D017510:Protein Folding; D011506:Proteins / Q000737:chemistry; D012259:Ribonuclease, Pancreatic / Q000737:chemistry*; D012260:Ribonucleases / Q000737:chemistry; D012965:Sodium Chloride / Q000737:chemistry; D013055:Spectrophotometry, Infrared; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods*; D055672:Static Electricity; D013696:Temperature; D013997:Time Factors; D014443:Tyrosine / Q000737:chemistry
D011506:Proteins; D001224:Aspartic Acid; D000431:Ethanol; D014443:Tyrosine; D012965:Sodium Chloride; D012260:Ribonucleases; D012259:Ribonuclease, Pancreatic