ABSTRACT
A Type II phospholipase A2 myotoxin from Agkistrodon contortrix laticinctus was purified to homogeneity and crystallized. The protein had only myotoxic activity. X-ray diffraction quality crystals were obtained by the hanging drop vapour diffusion method from a crystallization solution containing 2.0 M ammonium sulphate. X-ray data were collected to a resolution of 2.3 A, and the crystals are fully characterized.
Subject(s)
Agkistrodon , Crotalid Venoms/chemistry , Mycotoxins/chemistry , Phospholipases A/chemistry , Animals , Crotalid Venoms/enzymology , Crystallography, X-Ray , Phospholipases A2ABSTRACT
Influenza C virus contains a single surface glycoprotein in its lipid envelope which is the hemagglutinin-esterase-fusion glycoprotein (HEF). HEF binds cell-surface receptors, is a receptor-destroying enzyme (a 9-O-acetylesterase), and mediates the fusion of virus and host cell membranes. A bromelain-released soluble form of HEF has been crystallized. Two different tetragonal forms have been identified from crystals with the same morphology [P(1(3))22, a = b = 154.5, c = 414.4 A, and P4(1(3))2(1)2, a = b = 217.4, c = 421.4 A]. Both crystal forms share a common packing scheme. Synchrotron data collection and flash cooling of crystals have been used for high-resolution data collection.
ABSTRACT
Fusion of the influenza viral membrane with the membrane of the host cell is preceded by a low pH induced conformation change in the viral haemagglutinin. A fragment, consisting of much of the stem domain of influenza haemagglutinin in the low pH induced conformation, has been crystallized by the vapour diffusion method. Several crystal forms have been obtained and the molecular packing in these crystals is discussed. Crystals suitable for the recording of high angle X-ray diffraction data grow in space group C222(1). Diffraction data have been recorded from crystals cooled to -170 degrees C in a cryoprotectant buffer.
Subject(s)
Hemagglutinins, Viral/chemistry , Crystallization , Crystallography, X-Ray , Hydrogen-Ion Concentration , Molecular Weight , Orthomyxoviridae/chemistry , Peptide Fragments/chemistry , Protein ConformationABSTRACT
The structure of the human cytokine, interleukin 1-beta (IL1-beta) is composed almost wholly of anti-parallel beta-sheet, organized in a three-fold repeating motif. The beta strands comprising the protein core are interconnected by 11 surface loops that form prominent features on the surface of the molecule. Comparisons of the amino acid sequences of different species of IL1-beta and the related cytokine IL1-alpha show that the majority of conserved residues form the structural core of the molecule, and that most variability occurs in the termini and surface loops that presumably bind the IL1 receptor. These results suggest that there may be some degree of flexibility in interactions made between IL1 and its cell surface receptor.
