Tests of the simple model of Lin and Brandts for the folding kinetics of ribonuclease A

Franz X. Schmid, Michael H. Buonocore, Robert L. Baldwin

Research output: Contribution to journalArticle

22 Citations (Scopus)

Abstract

L.-N. Lin and J. F. Brandts recently proposed a simple model for the folding kinetics of ribonuclease A in which folding intermediates are not detectable. We have tested the basic assumption of the simple model for the major unfolded species, which is produced by a slow isomerization (the "X ⇌ Y reaction" according to Lin and Brandts) after unfolding. The simple model assumes that in refolding the slow Y → X reaction must occur before any folding can take place. We have measured the Y → X reaction during folding. Tyrosine-detected folding occurs before the Y → X reaction; the difference in rate between the Y → X reaction and folding monitored by tyrosine absorbance becomes large when the stabilizing salt 0.56 M (NH4)2SO4 is added. The simple model predicts that the kinetic properties of the X ⇌ Y reaction in unfolded ribonuclease are the same as those of tyrosine-detected folding. We find, however, that the kinetics of the X ⇌ Y reaction in unfolded ribonuclease are independent of urea concentration, whereas the rate of tyrosine-detected folding decreases almost 100-fold between 0.3 and 5 M urea, as reported by Lin and Brandts. We point out that the kinetic properties of the X ⇌ Y reaction in unfolded ribonuclease are characteristic of proline isomerization.

Original languageEnglish (US)
Pages (from-to)3389-3394
Number of pages6
JournalBiochemistry
Volume23
Issue number15
StatePublished - 1984
Externally publishedYes

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Pancreatic Ribonuclease
Tyrosine
Ribonucleases
Kinetics
Isomerization
Urea
Proline
Salts

ASJC Scopus subject areas

  • Biochemistry

Cite this

Schmid, F. X., Buonocore, M. H., & Baldwin, R. L. (1984). Tests of the simple model of Lin and Brandts for the folding kinetics of ribonuclease A. Biochemistry, 23(15), 3389-3394.

Tests of the simple model of Lin and Brandts for the folding kinetics of ribonuclease A. / Schmid, Franz X.; Buonocore, Michael H.; Baldwin, Robert L.

In: Biochemistry, Vol. 23, No. 15, 1984, p. 3389-3394.

Research output: Contribution to journalArticle

Schmid, FX, Buonocore, MH & Baldwin, RL 1984, 'Tests of the simple model of Lin and Brandts for the folding kinetics of ribonuclease A', Biochemistry, vol. 23, no. 15, pp. 3389-3394.
Schmid, Franz X. ; Buonocore, Michael H. ; Baldwin, Robert L. / Tests of the simple model of Lin and Brandts for the folding kinetics of ribonuclease A. In: Biochemistry. 1984 ; Vol. 23, No. 15. pp. 3389-3394.
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