4IT2

Mn(III)-PPIX bound Tt H-NOX

Summary for 4IT2

• Entry DOI: 10.2210/pdb4it2/pdb
• Related: 1U4H 1U55 1U56 3EEE 3M0B 3SJ5
• Descriptor: Methyl-accepting chemotaxis protein, MANGANESE PROTOPORPHYRIN IX (3 entities in total)
• Functional Keywords: o2-sensing heme domain, oxygen binding
• Biological source: Caldanaerobacter subterraneus subsp. tengcongensis (Thermoanaerobacter tengcongensis)
• Total number of polymer chains: 2
• Total formula weight: 45941.74

Authors

Winter, M.B.,Klemm, P.J.,Phillips-Piro, C.M.,Raymond, K.M.,Marletta, M.A. (deposition date: 2013-01-17, release date: 2013-02-27, Last modification date: 2023-09-20)

Primary citation

Winter, M.B.,Klemm, P.J.,Phillips-Piro, C.M.,Raymond, K.N.,Marletta, M.A.
Porphyrin-Substituted H-NOX Proteins as High-Relaxivity MRI Contrast Agents.
Inorg.Chem., 52:2277-2279, 2013

PubMed Abstract: Heme proteins are exquisitely tuned to carry out diverse biological functions while employing identical heme cofactors. Although heme protein properties are often altered through modification of the protein scaffold, protein function can be greatly expanded and diversified through replacement of the native heme with an unnatural porphyrin of interest. Thus, porphyrin substitution in proteins affords new opportunities to rationally tailor heme protein chemical properties for new biological applications. Here, a highly thermally stable Heme Nitric oxide/OXygen binding (H-NOX) protein is evaluated as a magnetic resonance imaging (MRI) contrast agent. T1 and T2 relaxivities measured for the H-NOX protein containing its native heme are compared to the protein substituted with unnatural manganese(II/III) and gadolinium(III) porphyrins. H-NOX proteins are found to provide unique porphyrin coordination environments and have enhanced relaxivities compared to commercial small-molecule agents. Porphyrin substitution is a promising strategy to encapsulate MRI-active metals in heme protein scaffolds for future imaging applications.

PubMed: 23394479
DOI: 10.1021/ic302685h

Experimental method

X-RAY DIFFRACTION (2.097 Å)