Fraction of galline, a protamine from fowl sperm, and some characterization of the components

Protamines and other basic proteins from spermatozoa of molluscs

The basic proteins obtained from spermatozoa of different species of the phylum Mollusca have been extracted and fractionated. The amino acid analysis and electrophoretic mobility of these proteins show a considerable variation in the types and relative amounts of the components present in different species. In some case-(Gibbula, Haliotis, Loligo, Octopus) the main components are similar to the protamines found in the salmonid fishes, although they appear to be larger in size (40-80 amino acids) and show significant differences in amino acid composition. In other cases (Mytilus, Chiton) a complex mixture of proteins is present, which including somatic-like histones and proteins intermediate in size and composition betweeln protamines and histones. Other molluscs (Ostrea, Spisula, Patella) also contain proteins intermediate in composition between protamines and histones, but their molecular weight appears to be larger than in histones. In Eledone a complex mixture of proteins containing cystine is obtained, with some components rich in arginine. In most species, somatic-like histones are also present. Their type and relative amount are different in each species. The significance of these results towards an understanding of the evolutionary history of these proteins is discussed. It is suggested that these proteins evolved from histone precursors.

Protamines, histones and the genetic code. New evidence for code evaluations

A new approach is presented to give evidence for the theories of Jukes and Crick (1-3) that at a more primitive stage the genetic code consisted of doublets separated by "comma-bases" rather than true triplets and that G and C or A and U are the exclusive bases used by the primordial code. This approach makes use of the conservation of the histone IV sequence over extremely long periods of time by comparing the amino acid composition of the average vertebrate protein with the one of histone IV, a reconstructed ancestral polypeptide and various nuclear proteins, homologous or otherwise related to it. All protamines studied and the majority of histones show deviations from the average vertebrate protein which are statistically highly significant if the amino acids sufficiently coded for by the first two bases are compared. A similar result is obtained for those amino acids which are sufficiently coded for by the first two bases of the codon and have codons composed of G and C only.

The heterogeneity of the protamines from human spermatozoa

Nuclear basic protein from ejaculated human spermatozoa were labelled with iodo[14C1]acetic acid and fractionated by ion-exchange chromatography into several pools (named A-K). Gel electrophoresis indicated that the minor protamine components, were present in pool D and that, of the major protamine components, component 1 (pools E, F, G, H) was well separated from the unresolved mixture of component 2 and component 3 (pools I, J, K). Pools G and J were free of other contaminants. Pools D, G, and J produced different radioactive peptides on digestion with trypsin and with thermolysin, and also had quite distinct amino acid compositions. This suggests that the heterogeneity of human protamines is caused by differences in amino acid sequence. Major component 1 also seems to be heterogenous, since it was found in two distinct peaks (pools E and G), but post-translational modification as a cause of the two types of component 1 has not been ruled out. Although all the human protamine components are similar to other mammalian protamines in containing half-cysteine and tyrosine, they also have unique common features such as high histidine and high glutamic acid contents.