Showing papers on "Peptide sequence published in 1975"

Identification, purification and properties of clone-specific glycoprotein antigens constituting the surface coat of Trypanosoma brucei.

Abstract: Soluble glycoproteins have been purified from a series of clones of Trypanosoma brucei 427. Each clone yielded a characteristic predominant glycoprotein which induced clone-specific immunity to trypanosome infection in mice. These glycoproteins were shown by specific labelling and enzyme digestion of cells to be the major components of the trypanosome surface coat. Each glycoprotein consisted of a single polypeptide chain having an apparent molecular weight of 65 000 (as measured by SDS-polyacrylamide gel electrophoresis) and containing around 600 amino acid and 20 monosaccharide residues. Preliminary structural studies indicated large changes in amino acid sequence dispersed over a considerable length of the polypeptide chain. Proteolytic activity was demonstrated in semi-purified trypanosome extracts, providing one reason for the heterogeneity sometimes observed in surface glycoprotein antigen preparations.

Structure of chicken muscle triose phosphate isomerase determined crystallographically at 2.5 angstrom resolution using amino acid sequence data.

Abstract: Structure of chicken muscle triose phosphate isomerase determined crystallographically at 2.5A resolution: using amino acid sequence data

Amino-acid sequence and oligosaccharide attachment sites of human erythrocyte glycophorin.

Abstract: Glycophorin, the major sialoglycoprotein of the human erythrocyte membrane, is composed of 131 amino acids and an average of 16 oligosaccharide chains. Fifteen oligosaccharides are linked to threonine/serine residues via O-glycosidic bonds, and one more complex unit is attached to asparagine. The location of each of these oligosaccharides and the complete amino-acid sequence of this molecular have been determined by Edman degradation techniques. Glycophorin appears to be organized into three distinct "domains" on the basis of the locations of glycosylated amino acids and the clustering of residues of similar type. These include (i) a glycosylated segment composed of approximately 64 residues from the NH2-terminus, (ii) a "hydrophobic" segment of approximately 32 nonpolar residues, and (iii) a COOH-terminal segment, composed of approximately 35 residues, which has an unusual concentration of hydrophilic amino acids. This unique structure is consistent with the earlier suggestions that glycophorin is one of the major "intrinsic" membrane proteins which has a transmembrane orientation.

Stereochemical basis of heat stability in bacterial ferredoxins and in haemoglobin A2.

Abstract: MOST enzymes are quickly inactivated above about 55 °C but those from thermophile bacteria are stable for long periods at higher temperatures1. We do not know why because so far their structures have proved too complex. For example although the tertiary and quaternary structures of the enzyme glyceraldehyde phosphate dehydrogenase from lobster muscle and from Bacterium stearothermophilus are alike their amino acid sequences differ by more than 130 out of some 330 positions which makes it hard to decide why the stearothermophilus enzyme is more stable. The electron transfer protein ferredoxin offers a better chance because its single polypeptide chain contains fewer than 60 residues; its structure is known and its heat stability and amino acid sequence have been determined in both mesophile and thermophile bacteria. We have built an atomic model of this protein, replaced its amino acid side chains in turn to correspond to the published sequences and searched for possible causes of the greater heat stability of ferredoxins from thermophile bacteria. We found that it arises mainly from external salt bridges linking residues near the amino terminus to others near the carboxy terminus. Haemoglobin A2 a minor fraction of adult human haemoglobin which is a little more heat stable than the major fraction, haemoglobin A, seemed another good choice because its amino acid sequence differs from that of A at only 10 positions. The atomic model suggests that at only two of these positions are the replacements likely to contribute to the extra stability of haemoglobin A2 one replacement providing an extra hydrogen bond between the α1 and β1 subunits and the other adding two non-polar interactions to a surface crevice within the β subunits. To account for the increased heat stability of the two proteins the extra bond energy provided by these interactions need not be larger than 10 kJ for ferredoxin or 5 kJ for haemoglobin A2.

The complete amino acid sequence of ubiquitin, an adenylate cyclase stimulating polypeptide probably universal in living cells.

Abstract: The complete amino acid sequence was determined for bovine ubiquitin, and adenylate cyclase stimulating polypeptide, which is probably represented universally in living cells. Ubiquitin has a molecular weight of 8451 and consists of a single polypeptide chain containing 74 amino acid residues. It contains four arginine residues but no cysteine or trytophan residues. The first 61 amino acid residues were obtained by automated Edman degradations. Tryptic digestion of maleated ubiquitin yielded four peptide fragments that were resolved by molecular sieve chromatography and coded in order of decreasing chain length (MT-1, MT-2, MT-3, and MT-4). The automated sequenator determinations on native ubiquintin provided overlapping sequence data for three of these fragments that gave an order of MT-1, MT-3, and then MT-2; Peptide MT-4, a dipeptide, was therefore assigned to the C terminus, and the placement of peptide MT-2 was corroborated by analysis of data from carboxypeptidase digestions of maleated ubiquitin. Peptide MT-2 was domaleated and sequenced by manual Edman degradations through a single lysine residue. It was cleaved at this residue with trypsin, and the two resultant peptides were separated by ion-exchange chromatography. Manual sequencing of the C-terminal demaleated tryptic peptide of MT-2 completed the sequence of MT-2 and that of native ubiquitin. The sequence of ubiquitin was further confirmed and supported by amino acid and parital sequence anlysis of fragments obtained by digestion of maleated ubiquitin with chymotrypsin or staphylococcal protease.

Studies on the primary structure of the influenza virus hemagglutinin

Abstract: The amino-terminal sequence and composition of the subunits of the hemagglutinin (HA) of influenza virus has been determined. The hemagglutinin has been isolated by two techniques. (1) as the intact hemagglutinin after disruption of the virus in sodium dodecyl sulfate, giving 2 subunits of 58,000 daltons (HA1) and 26,000 daltons (HA2), and (2) after treatment of the virus with bromelain, giving 2 subunits of 58,000 daltons (BHA1) and 21,000 daltons (BHA2). In both preparations these subunits are linked by disulfide bonds. The aminoterminal sequences of HA1 and BHA1, and HA2 and BHA2 are the same. The composition of the 50 residue peptide associated with the membrane, which is removed from the C-terminus of HA2 by bromelain, is deduced and shown to be hydrophobic and contain 50% of the serine residues of HA2. The biosynthetic precursor of the hemagglutinin has been purified from the membranes of abortively infected chick fibroblasts and shown to have the same amino terminus as HA1. Thus the order of biosynthesis is NH2-HA1-HA2-COOH. The amino-terminal sequence of BHA2--at the cleavage site of the precursor--is shown to be a palindrome: NH2-Gly-Leu-Phe-Gly-Ala-Ile-Ala-Gly-Phe-Ile-. This sequence is conserved in representative viruses from each of the major pandemics. A region of homologous sequence is described between the hemagglutinins of influenza type A and B viruses.

Homology in amino-terminal sequence of precursors to pancreatic secretory proteins

Abstract: Sequence determination of up to 24 amino-terminal residues of several putative precursors for dog pancreas secretory proteins, synthesized in vitro by translation of their mRNA's in the presence of radioactively labeled amino acids, revealed extensive sequence homology in the 16 amino-terminal residues. It is suggested that this common sequence constitutes a metabolically short-lived peptide extension which precedes the amino-terminal sequences of all pancreatic secretory proteins and that it functions in the transfer of these proteins across the microsomal membrane. This sequence was found to contain an unusually large percentage of hydrophobic residues.

Molecular basis of beta-galactosidase alpha-complementation.

Abstract: In previous studies, a cyanogen bromide peptide derived from amino-acid residues 3-92 of beta-galactosidase (EC 3.2.1.23; beta-D-galactoside galactohydrolase) was shown to have alpha-donor activity in intracistronic alpha-complementation. We have now isolated the defective beta-galactosidase alpha-acceptor protein from the deletion mutant strain M15 of Escherichia coli and find that it lacks residues 11-41 of betal-galactosidase. This is demonstrated by the isolation and sequence determination of a cyanogen bromide peptide from the M15 protein, which is identical to the corresponding peptide from beta-galactosidase except for the missing amino acids. We conclude that the alpha-donor peptide restores the region missing in the M15 protein.

Amino Acid Substitution and the Antigenicity of Globular Proteins

Abstract: Publisher Summary This chapter discusses the amino acids substitution and the antigenicity of globular proteins. It focuses on the role of sequential determinants, related to the amino acid sequence of peptides, and conformational determinants, the product of protein conformation not expressed in linear peptides. The experimental approaches employed to provide the amino acid substitutions are from the chemical modification of single residues, use of naturally occurring amino acid mutants, and use of a series of genetically homologous proteins of known sequence. It indicates that antibodies are best produced to regions of protein antigens that bear sequences different from those of homologous proteins of the immunized species. Also, globular proteins have highly immunogenic and relatively constant surface patches, the specificity of which is determined by their amino acid composition. The chapter discusses the importance of slight genetic changes in determining antigenic specificity. In certain crucial sites, a single amino acid difference resulting from one point mutation can alter conformation and determine complete specificity between two protein antigens.

Interaction of epidermal growth factor (EGF) with cultured fibroblasts.

Abstract: Publisher Summary This chapter discusses the interaction of epidermal growth factor (EGF) with cultured fibroblasts. EGF is a single-chain polypeptide containing a total of 53 amino acid residues. All the common amino acids are present except lysine, alanine, and phenylalanine. The molecule contains six half-cystine residues in disulfide bridges. EGF is antigenic and is sensitive to proteolytic digestion. It is heat stable, nondialyzable, and has an isoelectric point at pH 4.6. The chapter also discusses the complete amino acid sequence of EGF and presents the location of the three disulfide bridges. A direct stimulatory effect of EGF on epithelial cell proliferation in vitro has been demonstrated in a number of organ culture systems. These include embryonic skin, embryonic cornea, and mammary gland expiants. The effects of EGF are not species specific; expiants derived from the chick, mouse, and human are responsive. The stimulation of epidermal proliferation in organ cultures of chick embryo skin is dependent upon a number of conditions, among which are the age of the embryo and the presence of dermal cells.

Molecular conservation of 74 amino acid sequence of ubiquitin between cattle and man

Abstract: UBIQUITIN (originally ‘ubiquitous immunopoietic polypeptide’ or ‘UBIP’)1 induces lymphocyte differentiation and was first found in bovine thymus during isolation of the thymic polypeptide hormone thymopoietin (originally ‘thymin’)2 which induces T-cell differentiation3 and has secondary effects on neuromuscular transmission2. Ubiquitin, which has a molecular weight of 8,451, is interesting for several reasons. First, it induces differentiation of T cells and, unlike thymopoietin, B cells1. Second, both properties are inhibited by the β-adrenergic blocking agent propranolol, and so the capacity of ubiquitin to induce lymphocyte differentiation seems to depend on reaction with a β-adrenergic receptor. Third, ubiquitin activates adenyl cyclase in lymphocyte precursors and in other tissues, again through a, β-adrenergic receptor (M. Bitensky, and G. G., unpublished). Finally, ubiquitin, as the name implies, is found not only in thymus but in all other animal cells and in yeasts, bacteria and higher plants1. Although its physiological function remains unknown, ubiquitin must be vital to the living cell to have been conserved over such a long evolutionary time span. We have reported the complete primary structure of bovine ubiquitin4—a single polypeptide chain of 74 amino acids—and now report that human ubiquitin has an identical sequence.

A-Protein gene of bacteriophage MS2

Abstract: The nucleotide sequence of the A-protein gene of bacteriophage MS2 has been determined and a model for its secondary structure is proposed. Also the amino acid sequence of the A-protein has been almost completely elucidated.

Amino acid sequence studies on plasmin-derived fragments of human fibrinogen: amino-terminal sequences of intermediate and terminal fragments.

Abstract: The progressive changes in amino-terminal sequence brought about by the digestion of human fibrinogen by plasmin have been studied. In addition, the limit products (fragments D and E) have been isolated and characterized in the same way. These studies have confirmed the generally accepted scheme of fibrinogen being changed into a large molecular weight fragment X, which in turn is converted into an intermediate fragment Y and a limit fragment D, followed by the breakdown of fragment Y into an additional fragment D and another core fragment E. Our data allow the precise identification of several of the junctions being attacked, including one in a region of the gamma-chain whose sequence has not previously been reported. The cleavages are not singular in any case, however, and, as suggested by others, intermediate species exist which correspond to "early D," "late D," etc. In addition to localizing the exact bonds split by plasmin, we have been able to sequentially position the core fragments relative to each other, since the gamma-chain amino terminus of fragment D has been found to be contiguous to the known carboxy-terminal sequence of fragment E.