Conventional transmission electron microscopy of 1-1 haptoglobin isolated molecules and paracrystalline aggregates.

Data are presented relating conventional transmission electron microscope (CTEM) ultrastructural observations of the monomeric phenotypic variant (Hp 1-1) of the haptoglobin class of blood glycoproteins. Through comparison of these findings with homologous published data, obtained by means of scanning transmission electron microscopy (STEM), the validity of CTEM in molecule shape and fine structure determination is confirmed. An experimental procedure for Hp 1-1 crystallization is also reported.

Covalent binding to proteins as a mechanism of chemical toxicity.

The capacity of chemicals to interact covalently with cellular macromolecules in in vitro systems was exploited to elucidate the structure of secondary metabolites, namely arene oxide derivatives, in the biotransformation of styrene. Covalent binding to proteins was also determined to check the presence and activity of enzymatic systems in subcellular compartments other than microsomes, e.g., nuclei. In experiments with cyclophosphamide as substrate it was shown that nuclear enzymatic activities might well be responsible for drug covalent binding to DNA.