English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

For the first time, a circularly permuted human beta-globin (cpbeta) has been coexpressed with human alpha-globin in bacterial cells and shown to associate to form alpha-cpbeta hemoglobin in solution. Flash photolysis studies of alpha-cpbeta show markedly biphasic CO and O(2) kinetics with the amplitudes for the fast association phases being dominant due the presence of large amounts of high-affinity liganded hemoglobin dimers. Extensive dimerization of liganded but not deoxygenated alpha-cpbeta was observed by gel chromatography. The rate constants for O(2) and CO binding to the R state forms of alpha-cpbeta are almost identical to those of native HbA (k'(R(CO)) approximately 5.0 microM(-1) s(-1); k'(R(O(2))) approximately 50 microM(-1) s(-1)), and the rate of O(2) dissociation from fully oxygenated alpha-cpbeta is also very similar to that observed for HbA (k(R(O(2))) approximately 21-28 s(-1)). When the equilibrium deoxyHb form of alpha-cpbeta is reacted with CO in rapid mixing experiments, the observed time courses are monophasic and the observed bimolecular association rate constant is approximately 1.0 microM(-1) s(-1), which is intermediate between the R state rate measured in partial photolysis experiments (approximately 5 microM(-1) s(-1)) and that observed for T state deoxyHbA (k'(T(CO)) approximately 0.1 to 0.2 microM(-1) s(-1)). Thus the deoxygenated permutated beta subunits generate an intermediate, higher affinity, deoxyHb quaternary state. This conclusion is supported by equilibrium oxygen binding measurements in which alpha-cpbeta exhibits a P(50) of approximately 1.5 mmHg and a low n-value (approximately 1.3) at pH 7, 20 degrees C, compared to 8.5 mmHg and n approximately 2.8 for native HbA under identical, dilute conditions.

Coexpression of Human α- and Circularly Permuted β-Globins Yields a Hemoglobin with Normal R State but Modified T State Properties