Clupeine molecular weight

Protamines. Strongly basic proteins of low molecular weight (4,000 to 8,000). They are rich in arginine. Examples are clupein from herring and scombrin from mackerel. 

The low viscous character could further be connected (as above in the case of Na-yeast nucleate) with the macromolecules being very short, consisting only of a few monomeric residues. This once more does not strictly apply for clupein, the latter though a protein of relative low molecular weight (a few thousands) still consists of more than 30 amino acid residues linked together by peptide groups. 

Fish sperm contain nucleoprotattiines. Upon treatment with sulfuric acid, the nucleoprotamines are reduced to nucleic acid and protamine sulfate. The chemically heterogeneous protamines of molecular weight 2000-8000 thus obtained contain only a few different kinds of amino acid residues per molecule. They are relatively rich in basic amino acids, as the composition of the protamines clupeine and salmine shows (Table 29-4), and never contain cystine, aspartic acid, or tryptophan. The basic amino acids are responsible for the bonding of the protein to the nucleic acid component. 

During the intervening 40 years the estimation of the molecular weight of unfractionated or whole protamines has been carried out by various chemical and physical methods. Some of these values for typical protamines, clupeine and salmine, are listed in Table V-1 together with the methods used and literature references. 

Molecular Weight Table V-1. The molecular weight of clupeine and salmine ... 

Thus, the molecular formula Ala3 Ser3 Pro2 Val2 Arg2 was obtained for clupeine Z. The molecular weight calculated from the formula is 4,163 as a free base or 4,929 as its hydrochloride. 

A rechromatographed specimen of clupeine YII obtained unmodified by the chromatographic fractionation of TNP-(trinitrophenylated) whole clupeine (cf. Chap. VII. B. 3), has the molecular formula Arg2o Pro3 Ala2 2 Val2. This is based on the analysis of amino-acid composition and a molecular weight of about 5,000 for the hydrochloride as estimated by the DNP method (MW calculated from the amino acid composition 4,047 as a free base or 4,777 as the hydrochloride). 

Yamasaki, M. (1) Chemical and enzymic studies on protamines. II. N-Terminal residues and molecular weights of clupeine and salmine. Sci. Pap. Coll. Gen. Educ., Univ. Tokyo 9, 31—47 (1959). 

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