1iyn
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(New page: 200px<br /><applet load="1iyn" size="450" color="white" frame="true" align="right" spinBox="true" caption="1iyn, resolution 1.60Å" /> '''Crystal structure of...)
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Revision as of 20:40, 24 November 2007
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Crystal structure of chloroplastic ascorbate peroxidase from tobacco plants and structural insights for its instability
Overview
Ascorbate peroxidase (APX) is a heme-containing protein that plays a, central role in scavenging H(2)O(2) in higher plants. The structure of, stromal APX (sAPX) was determined at 1.6 A to an R-factor of 19.1% and an, R-free-factor of 22.3%. The electrostatic potential of the gamma-channel, that connects the molecular surface of sAPX to the gamma-edge of heme was, more positive than that of cytosolic APX (cAPX) from pea, so sAPX might, bind more easily with ascorbate than cAPX. The overall structure of sAPX, was similar to those of cAPX from pea and cytochrome c peroxidase (CCP), from yeast, with a substantial difference in a loop structure located in, the vicinity of the heme. The side chain of Arg169 in sAPX corresponding, to His169 in cAPX and His181 in CCP extended in the opposite direction, from the heme, forming two hydrogen bonds with carbonyl groups in the loop, structure. The rapid inactivation of sAPX might be due to the, characteristic conformation of Arg169 owing to the loop structure of sAPX.
About this Structure
1IYN is a Single protein structure of sequence from Nicotiana tabacum with NA and HEM as ligands. Active as L-ascorbate peroxidase, with EC number 1.11.1.11 Full crystallographic information is available from OCA.
Reference
Crystal structure of chloroplastic ascorbate peroxidase from tobacco plants and structural insights into its instability., Wada K, Tada T, Nakamura Y, Ishikawa T, Yabuta Y, Yoshimura K, Shigeoka S, Nishimura K, J Biochem (Tokyo). 2003 Aug;134(2):239-44. PMID:12966073
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