Ligation tunes protein reactivity in an ancient haemoglobin: kinetic evidence for an allosteric mechanism in Methanosarcina acetivorans protoglobin.

PLoS ONE. 2012;7(3):e33614 DOI 10.1371/journal.pone.0033614


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Journal Title: PLoS ONE

ISSN: 1932-6203 (Online)

Publisher: Public Library of Science (PLoS)

LCC Subject Category: Medicine | Science

Country of publisher: United States

Language of fulltext: English

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Stefania Abbruzzetti

Lesley Tilleman

Stefano Bruno

Cristiano Viappiani

Filip Desmet

Sabine Van Doorslaer

Massimo Coletta

Chiara Ciaccio

Paolo Ascenzi

Marco Nardini

Martino Bolognesi

Luc Moens

Sylvia Dewilde


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Time From Submission to Publication: 24 weeks


Abstract | Full Text

Protoglobin from Methanosarcina acetivorans (MaPgb) is a dimeric globin with peculiar structural properties such as a completely buried haem and two orthogonal tunnels connecting the distal cavity to the solvent. CO binding to and dissociation from MaPgb occur through a biphasic kinetics. We show that the heterogenous kinetics arises from binding to (and dissociation from) two tertiary conformations in ligation-dependent equilibrium. Ligation favours the species with high binding rate (and low dissociation rate). The equilibrium is shifted towards the species with low binding (and high dissociation) rates for the unliganded molecules. A quantitative model is proposed to describe the observed carbonylation kinetics.