Sweeney Astray

Quinlan, K.; Heaney, Seamus

doi:10.2307/40140673

Cited by 1 publication

(2 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…50 In addition, a few examples of natural proteins, which contain methylated His ligated to Cu, are deposited to the PDB. [29][30][31] While the amyloid-β peptide study discussed in the Introduction did compare εm H and δm H substitution, this was done within the context of fibril formation and not as an investigation of the electronic and structural differences that result from these changes. Thus, an exploration of the structural and electronic effects of either N δ or N ε nitrogen methylation on copper coordination as it relates to the tautomeric preferences of native copper enzymes, and the impact of these modifications on a catalytic reaction is warranted.…”

Section: Discussionmentioning

confidence: 99%

“…The only example of native m His bound to Cu can be found in the polysaccharide monooxygenase (PMO) family of enzymes secreted by several varieties of fungi. [29][30][31][32] The unique copper binding site of this protein family contains not only a m His but also a "histidine brace" motif due to binding of both the N-terminal m His residue's amine and side chain. The purpose of including a m His residue in the binding site is currently unknown; however, based on the results of the amyloid-β study referenced above, this may serve to increase the efficiency of the enzyme as compared to a His derivative.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Methylated Histidines Alter Tautomeric Preferences that Influence the Rates of Cu Nitrite Reductase Catalysis in Designed Peptides

Koebke

Stappen

et al. 2019

J. Am. Chem. Soc.

View full text Add to dashboard Cite

Copper proteins have the capacity to serve as both redox active catalysts and purely electron transfer centers. A longstanding question in this field is how the function of histidine ligated Cu centers are modulated by δ vs ε-nitrogen ligation of the imidazole. Evaluating the impact of these coordination modes on structure and function by comparative analysis of deposited crystal structures is confounded by factors such as differing protein folds and disparate secondary coordination spheres that make direct comparison of these isomers difficult. Here, we present a series of de novo designed proteins using the noncanonical amino acids 1-methyl-histidine and 3methyl-histidine to create Cu nitrite reductases where δor ε-nitrogen ligation is enforced by the opposite nitrogen's methylation as a means of directly comparing these two ligation states in the same protein fold. We find that ε-nitrogen ligation allows for a better nitrite reduction catalyst, displaying 2 orders of magnitude higher activity than the δ-nitrogen ligated construct. Methylation of the δ nitrogen, combined with a secondary sphere mutation we have previously published, has produced a new record for efficiency within a homogeneous aqueous system, improving by 1 order of magnitude the previously published most efficient construct. Furthermore, we have measured Michaelis-Menten kinetics on these highly active constructs, revealing that the remaining barriers to matching the catalytic efficiency (k cat /K M) of native Cu nitrite reductase involve both substrate binding (K M) and catalysis (k cat).

show abstract

Section: Discussionmentioning

confidence: 99%