Histones from the Fruit Fly Ceratitis capitata

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Abstract
Histones from the fruit fly Ceratitis capitata have been obtained and characterized by amino acid analysis and polyacrylamide gel electrophoresis. It has been found that the five major histone groups are present in this insect. The fractionation of histones has been achieved by using acid or organic selective extractions. Ceratitis capitata F1 exhibited a reduced electrophoretic mobility when compared with the mammalian corresponding histone. On the contrary, fly F2A1, mobility was similar to that of mammalian homologous histone. Some differences were found, however, in amino acid composition. It has been found that cysteine does not occur in fly F2A1, but this amino acid seemed to be present in the F3 histone, which aggregated under oxidizing conditions. A strongly basic protein was isolated together with histones when pharate adult chromatin was used as starting material. Amino acid analysis of this protein revealed the presence of hydroxyproline (19%), as well as high amounts of threonine (30%) and arginine (23%). It was found that this specific protein was not a nuclear component and it seemed to be located at the pharate adult envelope; the name of purarium‐specific protein is proposed for this protein. Its strongly basic nature is judged to be the cause by which it became attached to chromatin during the isolation procedure.