Polypeptide analysis of genotypic variants of occluded Heliothis spp. baculoviruses

The structural polypeptides of 12 baculovirus isolates which included nuclear polyhedrosis viruses (NPVs) and granulosis viruses (GVs) obtained from four different species of the insect genus Heliothis collected in different geographical regions of the world were characterized using sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The matrix proteins were compared according to their molecular weights and peptide profiles produced after limited proteolysis. Examination of the matrix and virion polypeptide profiles revealed three major polypeptide phenotypes which corresponded to the three baculovirus morphological groups; singly embedded nuclear polyhedrosis viruses (SNPVs), multiply embedded nuclear polyhedrosis viruses (MNPVs), and granulosis viruses (GVs). Enveloped nucleocapsid polypeptide profiles of isolates within each NPV phenotype differed in only one polypeptide whereas the two GV isolates differed by as many as five polypeptides. Nucleocapsid polypeptide profiles of isolates within each of the NPV subgroups were identical while those profiles from the GV nucleocapsids differed slightly in molecular weight of one polypeptide.     

Characterisation of mitochondrial fractions isolated from four genotypes of wheat coleoptiles

Mitochondrial fractions were isolated at various stages of germination from wheat coleoptiles of 4 different genotypes: WRH, Capitole, male-sterile Capitole (MSC) and F₁ hybrid obtained by crossing MSC with WRH. The ADP: O values were the highest in F₁ and in MSC and decreased during germination. The oxygen consumption was weaker in F₁ and in WRH than in the other genotypes. Quantitative differences in polypeptides exist between the different genotypes. On germination, increase in the polypeptides of high MW was more rapid in F₁ than in the other genotypes. The fatty acids of the mitochondria of F₁ and MSC are characterized by an abundance of linoleic acid. The content of this fatty acid decreased during germination more rapidly in F₁ and in MSC than in the others. The cytoplasm of Triticum timopheevi has a marked influence on mitochondria of MSC and F₁. This cytoplasm confers better oxidative properties, which can be correlated with changes in their biochemical constituents. However the F₁ hybrid differs from the other genotypes in many biochemical features.     

A Comparison of In Vitro- and In Vivo Phosphorylated Neurofilament Polypeptides

Abstract: Neurofilament polypeptides phosphorylated in vitro by incubation of neurofilament-enriched preparations from rat CNS with [γ-³²P]ATP were compared with the corresponding polypeptides labeled in vivo by injection of ³²P_i into the lateral ventricles of rats. Autoradiography of sodium dodecyl sulfate (SDS)-polyacrylamide gels revealed that the major phosphorylated species in both preparations were the three neurofilament subunits, which have molecular weights of 200K, 145K, and 68K. However, the relative levels of ³²P detected in the three in vitro -labeled subunits differed from the relative in vivo levels. The two larger neurofilament polypeptides displayed similar ³²P isoprotein distribution patterns on two-dimensional gels, whereas additional isoproteins were seen in the in vitro -labeled 68K species. Limited proteolysis in SDS-polyacrylamide gels revealed the presence of common phosphopeptides in the corresponding pairs of in vitro- and in vivo-labeled subunits, but the in vivo -labeled 145K and in vitro -labeled 200K polypeptides contained additional digestion products. Two-dimensional peptide mapping of the 68K polypeptide digested with a mixture of trypsin and chymotrypsin indicated that this component was phosphorylated at a single, identical site, both in vivo and in vitro. These results indicate that the protein kinase that copurifies with neurofilament preparations may be involved in their in vivo phosphorylation.     

Isolation and characterization of a 23 kDa protein essential for photosynthetic oxygen evolution

A 23 kDa protein has recently been demonstrated to participate in photosynthetic oxygen evolution by reconstitution experiments on inside-out thylakoid vesicles (Åkerlund H-E, Jansson C and Andersson B (1982) Biochim Biophys Acta 681:1–10). Here we describe the isolation of the 23 kDa protein from a spinach chloroplast extract using ion-exchange chromatography. The protein was obtained in a yield of 25% and with less than 1% of contaminating proteins. The ability of the protein to stimulate oxygen evolution in inside-out thylakoids was preserved throughout the various fractionation steps. The isolated protein was highly water soluble and appeared as a monomer. Its isoelectric point was at pH=7.3. The amino acid composition showed a high content of polar amino acids, resulting in a polarity index of 49%. The isolated protein lacked metals and other prosthetic groups. Its function as a catalytic or regulating subunit in the oxygen evolving complex is discussed.Abbreviations kDa kiloDalton - PAGE polyacrylamide gel electrophoresis