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Spectroscopic characterization of rhino viral protease 2a: Zn is essential for the structural integrity
Author(s) -
Voss Tilman,
Meyer Rainer,
Sommergruber Wolfgang
Publication year - 1995
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1002/pro.5560041209
Subject(s) - zinc , chemistry , random coil , crystallography , protease , structural motif , molten globule , denaturation (fissile materials) , protein secondary structure , biophysics , fluorescence , binding site , fluorescence spectroscopy , protein structure , circular dichroism , enzyme , stereochemistry , biochemistry , biology , organic chemistry , nuclear chemistry , physics , quantum mechanics
Recently, protease 2A of human rhinovirus 2 (HRV2 2A) was shown to require a zinc ion for the formation of an active enzyme although zinc is not involved mechanistically. The data presented clearly show that the zinc ion bound to a picornaviral‐specific motif represents an essential component of the native structure, probably representing a new Zn‐binding motif. This structure, containing mostly β ‐strand elements as shown by CD spectroscopy, changes drastically upon removal of zinc. The zinc‐depleted form does represent an intermediate with mostly unchanged secondary structure, but not a fully denatured random coil as obtained by guanidinium hydrochloride. This is indicated by the blue‐shifted fluorescence spectra and by CD. The native protein exhibited a cooperative phase transition at 53 °C. In contrast, the zinc‐depleted form did not show any transition at all, again demonstrating the stabilizing role of the zinc ion. A structural intermediate was observed during thermal and pH denaturation that may represent a molten globule, as suggested by its ANS binding.