Medizinische Universität Graz Austria/Österreich - Forschungsportal - Medical University of Graz
Gewählte Publikation:
Weinhäusel, A; Griessler, R; Krebs, A; Zipper, P; Haltrich, D; Kulbe, KD; Nidetzky, B.
alpha-1,4-D-glucan phosphorylase of gram-positive Corynebacterium callunae: isolation, biochemical properties and molecular shape of the enzyme from solution X-ray scattering.
Biochem J. 1997; 326 ( Pt 3)(4):773-783
Doi: 10.1042/bj3260773
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- Krebs Angelika
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- Abstract:
- The alpha-1,4-D-glucan phosphorylase from gram-positive Corynebacterium callunae has been isolated and characterized. The enzyme is inducible approx. 2-fold by maltose, but remarkably not repressed by D-glucose. The phosphorylase is a homodimer with a stoichiometric content of the cofactor pyridoxal 5'-phosphate per 88-kDa protein subunit. The specificity constants (kcat/Km, glucan) in the directions of glucan synthesis and degradation are used for the classification of the enzyme as the first bacterial starch phosphorylase. A preference for large over small substrates is determined by variations in the apparent binding constants rather than catalytic-centre activities. The contribution of substrate chain length to binding energy is explained assuming two glucan binding sites in C. callunae phosphorylase: an oligosaccharide binding site composed of five subsites and a high-affinity polysaccharide site separated from the active site. A structural model of the molecular shape of the phosphorylase was obtained from small-angle solution X-ray scattering measurements. A flat, slightly elongated, ellipsoidal model with the three axes related to each other as 1:(0.87-0.95):0.43 showed scattering equivalence with the enzyme molecule. The model of C. callunae phosphorylase differs from the structurally well-characterized rabbit-muscle phosphorylase in size and axial dimensions.
- Find related publications in this database (using NLM MeSH Indexing)
- Animals -
- Corynebacterium - enzymology
- Crystallography, X-Ray -
- Magnetic Resonance Spectroscopy -
- Phosphorylases - chemistry
- Phosphorylases - isolation & purification
- Protein Conformation -
- Rabbits -