Author/Editor		Dieckmann, T; Mitschang, L; Hofmann, M; Kos, J; Turk, V; Auerswald, EA; Jaenicke, R; Oschkinat, H
Title		The structures of native phosphorylated chicken cystatin and of a recombinant unphosphorylated variant in solution
Type		članek
Source		J Mol Biol
Vol. and No.		Letnik 234, št. 4
Publication year		1993
Volume		str. 1048-59
Language		eng
Abstract		The solution structures of the phosphorylated form of native chicken cystatin and the recombinant variant AEF-S1M-M29I-M89L were determined by 2D, 3D and 4D-NMR. The structures turn out to be very similar, despite the substitutions and the phosphorylation of the wild-type. Their dominant feature is a five-stranded beta-sheet, which is wrapped around a five-turn alpha-helix, as shown by X-ray crystallographic studies of wild-type chicken cystatin. However, the NMR analysis shows that the second helix observed in the crystal is not present in solution. The phosphorylation occurs at S80, which is located in a flexible region. For this reason, very few effects on the structure are observed. Comparison of structures of the unphosphorylated variant and the wild-type shows small effects on H84 which is located in the supposed recognition site of the serine kinase. This recognition site appears to be well structured as a large loop-containing bulge of the beta-sheet. The N termini of both mutants, which contribute to a large extent to the binding to the proteinase, are very flexible. A loop structure involving the residues L7 to A10 as found in related inhibitors, such as in the kininogen domains 2 and 3, is not sufficiently populated to be observed.
Descriptors		CYSTATINS PHOSPHOPROTEINS AMINO ACID SEQUENCE CHICKENS MODELS, MOLECULAR MOLECULAR SEQUENCE DATA NUCLEAR MAGNETIC RESONANCE PROTEIN STRUCTURE, SECONDARY RECOMBINANT PROTEINS SOLUTIONS ULTRACENTRIFUGATION