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Biomedical subjects

M Kakudo

Publications and source records attributed to M Kakudo.

At least 37 records · Page 2Linked to original sources
PubMed1978

Crystallization and a 5 A X-ray diffraction study of Aphanothece sacrum ferredoxin.

A chloroplast-type ferredoxin containing two non-heme iron and two labile sulfur atoms per molecule was prepared from Aphanothece sacrum. Crystals were obtained by dialysis against 75% saturated a-monium sulfate solution, and belong to the tetragonal system with cell dimensions a = b = 92.2 A and c = 47.6 A, containing four molecules in an asymmetric unit. The electron density map at 5 A resolution was calculated by using the best phase angles determined by the single isomorphous replacement method coupled with the anomalous dispersion effect. An anomalous dispersion difference Fourier map for the native crystal clearly showed four humps corresponding to the iron atoms in an asymmetric unit. The electron densis surface.

Binding Sites↗
PubMed1978

X-ray analysis of ferredoxin from Spirulina platensis. II. Chelate structure of active center.

A chloroplast-type ferredoxin from Spirulina platenis crystallized in an orthorhombic system, space group C2221, with cell dimensions a=62.32, b=28.51, and c=108.08 A. The electron density map at 2.8 A resolution was prepared by using the best phase angles determined by the single isomorphous replacement method coupled with the anomalous dispersion method. The chelating structure of the acitve center was revealed as follows. Of the six cysteinyl residues in the molecule, Cys 41, Cys 4k, Cys 49, and Cys 79 are involved in the active center. Cys 41 and Cys 46 are coordinated to one iron atom, and Cys 49 and Cys 79 to the other iron atom. Only one of these cysteinyl residues, Cys 79, is comparatively apart from the other three in the amino acids sequence of the molecule, as found in the case of bacterial ferredoxin. It appears that the NH....S hydrogen bonds are around the active center, as in other non-heme iron sulfur proteins.

Binding Sites↗
PubMed1975

The crystal structure of bonito (katsuo) ferrocytochrome c at 2.3 A resolution. II. Structure and function.

The structure analysis of bonito heart ferrocytochrome c was carried out at 2.3 A resolution by X-ray diffraction, and a Kendrew-type skeletal model was built up. This molecule has an overall egg shape, 35 A in height, 30 A in width and 23 A in thickness; the 5th ligand of the heme iron atom is the N-epsilon atom of the His-18 imidazole ring and the 6th is the Met-80 sulfur atom. Distinct alpha-helix regions are found between the N-terminus and reside 11, between 60 and 69, and between 90 and the C-terminus. The most distinct difference between the conformation of the present molecule and that of the horse oxidized molecule is the location of the Phe-82 phenyl ring. In the present reduced molecule, the phyenyl ring is in closer contact with the iron atom and gives influences on the character of the iron atom. Inside the molecule, at the lower part of the heme pocket, there is an extended hydrogen bond network including the propionic acid residues of the heme group. Both Phe-82 and the hydrogen bond network may play a key role in the function of this molecule.

Amino Acid Sequence↗