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3tgb is a 1 chain structure with sequence from Rhodnius prolixus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Prestidigitation: In a mutant of the heme protein nitrophorin 4, the first binding of guanidine to iron in a porphyrin is observed. The protein pocket has two effects that aid this binding: its overall structure holds the ligands together providing binding energy from the chelate effect and it facilitates the deprotonation of the highly basic guanidine residue.
Guanidine-Ferroheme Coordination in the Mutant Protein Nitrophorin 4(L130R).,He C, Fuchs MR, Ogata H, Knipp M Angew Chem Int Ed Engl. 2012 Apr 27;51(18):4470-3. doi: 10.1002/anie.201108691., Epub 2012 Feb 14. PMID:22334402[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
↑ He C, Fuchs MR, Ogata H, Knipp M. Guanidine-Ferroheme Coordination in the Mutant Protein Nitrophorin 4(L130R). Angew Chem Int Ed Engl. 2012 Apr 27;51(18):4470-3. doi: 10.1002/anie.201108691., Epub 2012 Feb 14. PMID:22334402 doi:10.1002/anie.201108691