Computer-aided calculation of amino acid composition of proteins

Evolutionary relationships among gamma-carboxymuconolactone decarboxylases

gamma-Carboxymuconolactone decarboxylase (EC 4.1.1.44) from Azotobacter vinelandii resembled the isofunctional enzymes from Acinetobacter calcoaceticus and Pseudomonas putida. All three decarboxylases appeared to be hexamers formed by association of identical subunits of about 13,300 daltons. The A. vinelandii and P. putida decarboxylases cross-reacted immunologically with each other, and the NH2-terminal amino acid sequences of the enzymes differed in no more than 7 of the first 36 residues. In contrast, the A. calcoaceticus decarboxylase did not cross-react with the decarboxylase from A. vinelandii or P. putida; the NH2-terminal amino acid sequences of these enzymes diverged about 50% from the NH2-terminal amino acid sequence of the A. calcoaceticus decarboxylase.

The complete amino-acid sequence of a trout-testis non-histone protein, H6, localized in a subset of nucleosomes and its similarity to calf-thymus non-histone proteins HMG-14 and HMG-17

The complete amino acid sequence of a basic non-histone protein, H6, isolated from the chromatin of rainbow trout (Salmo gairdnerii) testis cells, has been determined. Protein H6, first described by D. T. Wigle and G. H. Dixon [J. Biol. Chem. 246, 5636--5644 (1971)] was extracted with 5% trichloracetic acid and purified by ion-exchange chromatography on carboxymethyl-cellulose (CM-52). Sequence analysis was performed by automatic Edman degradation of the amino terminus of the intact protein and a series of large fragments derived by cleavage with chymotrypsin, staphylococcal protease and with mild acid to cleave at aspartic acid residues. Protein H6 possesses 69 residues and shows considerable similarities to the 89-residue calf thymus HMG-17 protein previously sequenced [Walker, J. M., Hastings, J. R. B. & Johns, E. W. (1977) Eur. J. Biochem. 76, 461--468]. B. Levy W. and G. H. Dixon [Proc. Natl Acad. Sci. U.S.A. 74, 2810--2814 (1977)] have shown that H6 is selectively solubilized when trout testis nuclei (or chromatin) are digested with DNase I under conditions which preferentially hydrolyze that portion of DNA enriched in transcribed sequences [Levy, W. B. & Dixon, G. H. (1977) Nucleic Acids Res. 4, 883--898]. Recently H6 has been located as a stoichiometric component of a distinct subset of trout testis nucleosomes that are complexed with a core nucleosome comprising 140 base pairs of DNA and the inner histones H2A, H2B, H3 and H4 [Levy, W. B., Connor, W. & Dixon, G. H. (1979) J. Biol. Chem., in the press].

Bovine fetus-specific serum proteins. Purification and characterization of alpha1-fetoprotein and immunological identification of alpha2- and beta-fetoproteins

Bovine alpha1-fetoprotein was isolated from fetal calf serum by successive procedures of concanavalin A-Sepharose chromatography, DEAE-Sephadex chromatography, SP-Sephadex chromatography and preparative disc polyacrylamide gel electrophoresis. The bovine alpha1-fetoprotein preparation was considered homogeneous by several physicochemical and immunochemical criteria. Bovine alpha1-fetoprotein has a molecular weight of 68 000 with an amino acid composiotn similar to that of other mammalian alhpa1-fetoprotein. In addition, bovine alpha1-fetoprotein was shown to exist as two distinct variants on the basis of carbohydrate heterogeneity. alpha2-Fetoprotein and a new beta-fetoprotein were immunologically identified in fetal calf serum. These fetoproteins, like alpha1-fetoprotein, were not detectable in non-pregnant cow serum by immunoelectrophoresis.

Isolation and partial characterization of human parotid basic proteins

Methods are presented for the isolation of basic proteins (Pb proteins) from human parotid saliva collected from humans possessing different alleles at the Pb locus. The proteins were found to be extremely basic, with an isoelectric point above 9.5. They contain approximately 45% of the basic amino acids histidine, lysine, and arginine, and are devoid of cysteine, proline, threonine, valine, methionine, and tryptophan. They are free of carbohydrate. A comparison of the amino acid sequence data of Pb protein to all available amino acid sequences revealed that no sequence similarities exist between the Pb proteins and any other proteins reported, although proteins of similar amino acid compositions have been reported by others. A model is presented with accounts for the several forms of allelic proteins based on observed amino acid sequence differences.

Human Pb, human post-Pb, and nonhuman primate Pb proteins: immunological and biochemical relationships

The isolation and characterization of a protein from human parotid saliva termed the "post-Pb protein" is described. By several criteria, this protein is closely related to the human Pb proteins. When reacted against antisera to human Pb protein in double diffusion, the post-Pb protein is found to be related to the Pb proteins by lines of identity. However, when the partial N-terminal amino acid sequences of the post-Pb protein and Pb proteins are compare, the sequences are not identical. Because of the similarity in size of the Pb and post-Pb proteins and because of the observed sequence differences, any product-precursor relationship between the Pb and post-Pb proteins is unlikely. The post-Pb protein probably is the product of a genetic locus different from the Pb locus. Two additional species of nonhuman primates (Papio papio and P. sphinx) have been found to have Pb proteins electrophoretically similar to these found in the rhesus monkey and differing from those in the human. The isolated Pb proteins of the rhesus monkey have been found to have close biochemical and immunological relationships to the human Pb proteins.

Immunochemical purification and characterization of ovine alpha-fetoprotein

Ovine alpha-fetoprotein was successfully isolated from fetal sheep serum by using rabbit anti-ovine alpha-fetoprotein linked to an agarose immunoadsorbent column. Antibody used in this affinity chromatography column was produced by immunizing a rabbit with highly purified alpha-fetoprotein-antibody complex to yield a monospecific antiserum to ovine alpha-fetoprotein. Following affinity chromatography, alpha-fetoprotein was further purified by preparative polyacrylamide disc gel electrophoresis ultimately yielding a 105-fold purification. The purified alpha-fetoprotein was homogeneous on analytical polyacrylamide disc gel electrophoresis. Ovine alpha-fetoprotein was found to be immunochemically related to human alpha-fetoprotein and to exhibit a molecular weight and amino acid composition similar to other mammalian alpha-fetoproteins.

The purification, characterization and partial sequence determination of a trout testis non-histone protein, HMG-T

A specific non-histone chromatin-associated protein, having a high content of both acidic and basic amino acids has been isolated from the chromatin of rainbow trout (Salmo gairdnerii) testis cells. The protein has been prepared by the extraction of chromatin with 0.35 M sodium chloride and purified by chromatography on carboxymethyl-cellulose with a gradient of lithium chloride at pH 9.0. The amino acid sequence of the first 29 residues of the amino-terminal region has been determined using an automatic protein sequencer. The primary structure of this protein differs from that of any of the histones yet sequenced and, therefore, cannot be a degradation produce of any of them. Moreover, the N-terminal amino acid sequence shows considerable similarity to the HMG-1 and HMG-2 chromosomal proteins described by Goodwin et al. [Eur. J. Biochem. 38, 14-19 (1973)] whose-N-terminal sequences were also determined in this laboratory.

Computer analysis of amino acid chromatograms

A procedure is described for the automatic off-line analysis of amino acid chromatograms of protein hydrolysates, using a small computer. The data requirements are basic, and, unlike previous programs, the present system allows the separation and identification of bands, as well as the quantitative determination of composition. With minor modification, the program could be extended for use with most types of chromatographic data. The validity of the application of the program to experimental data is discussed.