Energetic coupling between an oxidizable cysteine and the phosphorylatable N-terminus of human liver pyruvate kinase.

ABSTRACT: During our efforts to characterize the regulatory properties of human liver pyruvate kinase (L-PYK), we have noted that the affinity of the protein for phosphoenolpyruvate (PEP) becomes reduced several days after cell lysis. A 1.8 Å crystallographic structure of L-PYK with the S12D mimic of phosphorylation indicates that Cys436 is oxidized, the first potential insight into explaining the effect of "aging". Interestingly, the oxidation is only to sulfenic acid despite the crystal growth time period of 2 weeks. Mutagenesis confirms that the side chain of residue 436 is energetically coupled to PEP binding. Mass spectrometry confirms that the oxidation is present in solution and is not an artifact caused by X-ray exposure. Exposure of the L-PYK mutations to H₂O₂ also confirms that PEP affinit

SUBMITTER: Holyoak T 

PROVIDER: S-EPMC3572911 | biostudies-literature | 2013 Jan

REPOSITORIES: biostudies-literature